The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have inves...The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have investigated the fundamental reaction behaviors of nickel sulfide(NixSy)as lithium-ion battery anodes by in-situ TEM.We find that Ni_(3)S_(2)is the electrochemically stable phase,which appears in the first cycle of the NixSyanode.From the second cycle,conversion between Ni_(3)S_(2)and Li_(2)S/Ni is the dominant electrochemical reaction.In lithiation,the NixSynanoparticles evolve into a mixture of Ni nanocrystals embedded in Li_(2)S matrix,which form a porous structure upon full lithiation,and with the recrystallization of the Ni_(3)S_(2)phase in delithiation,a compact and interconnected network is built.Structural stability in cycles is susceptible to particle size and substrate restraint.Carbon substrate can certainly improve the tolerance for size-dependent pulverization of NixSynanoparticles.When NixSynanoparticle exceeds the critical size value,the morphology of the particle is no longer well maintained even under the constraints of the carbon substrate.This work deepens the understanding of electrochemical reaction behavior of conversiontype materials and helps to rational design of high-energy density battery anodes.展开更多
An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due ...An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due to the synergistically enhanced kinetics on enriched active sites and reconfigured electronic band structure. Here this work introduces hierarchical heterostructures into a NiMo@NiS/MoS_(2)@Ni_(2)S_(2)/MoO_(x)(NiMoS) composite by one-pot controlled moderative sulfidation. The optimal solvent composition and addition of NaOH enable NiMoS to own loose and porous structures, smaller nanoparticle sizes, optimal phase composition and chemical states of elements, improving the OER activity of NiMoS. To achieve current densities of 50 and 100 mA cm^(-1), small overpotentials of 275 and 306 mV are required respectively, together with a minor Tafel slope of 58 mV dec^(-1), which outperforms most reported sulfide catalysts and IrO_(2). The synergistic effects in the hierarchical heterostructures expose more active sites,adjust the electronic band structure, and enable the fast charge transfer kinetics, which construct an optimized local coordination environment for high OER electrocatalytic activity. Furthermore, the hierarchical heterostructures suppress the distinct lowering of electrical conductivity and collapse of pristine structures resulted from the metal oxidation and synchronous S leaching during OER, yielding competitive catalytic stability.展开更多
The availability of polymetallic ores is getting leaner in grade and is larger but inferior in volumes than in the past, making the extraction of copper, nickel and other non-ferrous metals metallurgically more diffic...The availability of polymetallic ores is getting leaner in grade and is larger but inferior in volumes than in the past, making the extraction of copper, nickel and other non-ferrous metals metallurgically more difficult to produce. The standard technologies, including enrichment and concentration, do not provide methods for obtaining monometallic concentrates and high extraction of metals into the commercial product. Pyrometallurgical processing of large volumes of poor raw materials is not economical and is complicated from the technological point of view. Conditions of chemical enrichment of poor natural materials have been studied with the use of technology of salt exchange leaching. The main impurity in sulfide ores of nonferrous metals is iron present in the forms of pyrite and pyrrhotite and the properties of chemical enrichment for nickel in pyrite concentrates has been investigated in this work. On the basis of thermodynamic analysis carried out with the use of Potential-pH Pourbaix’s Diagrams, it has been established that, with the use of nickel salt, it is possible to leach iron sulfides from ores. Based on the study of the mechanism and kinetics of the process of dissolution of iron sulfides with nickel salts, it was established that during the dissolution, the chemical composition and thermodynamic characteristics of the dissolved iron sulfides change—the residues from leaching are enriched with iron sulfides that are rich in sulfur and also result with elemental sulfur formation. Enrichment of leaching residues with sulfide iron with increased sulfur content and formation on the surface of nickel sulfide leads to increase of diffusional resistances and the process is limited by the velocity of mass transfer. To increase the velocity of the process and completeness of the reaction, it is necessary to activate the process, in particular, by grinding the solid phase.展开更多
Supercapacitors are favorable energy storage devices in the field of emerging energy technologies with high power density,excellent cycle stability and environmental benignity.The performance of supercapacitors is def...Supercapacitors are favorable energy storage devices in the field of emerging energy technologies with high power density,excellent cycle stability and environmental benignity.The performance of supercapacitors is definitively influenced by the electrode materials.Nickel sulfides have attracted extensive interest in recent years due to their specific merits for supercapacitor application.However,the distribution of electrochemically active sites critically limits their electrochemical performance.Notable improvements have been achieved through various strategies such as building synergetic structures with conductive substrates,enhancing the active sites by nanocrystallization and constructing nanohybrid architecture with other electrode materials.This article overviews the progress in the reasonable design and preparation of nickel sulfides and their composite electrodes combined with various bifunctional electric double-layer capacitor(EDLC)-based substances(e.g.,graphene,hollow carbon)and pseudocapacitive materials(e.g.,transition-metal oxides,sulfides,nitrides).Moreover,the corresponding electrochemical performances,reaction mechanisms,emerging challenges and future perspectives are briefly discussed and summarized.展开更多
Designing highly active and stable electrocata-lysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a challenge for energy con-version and storage technology.In this work,a S and N co-doped g...Designing highly active and stable electrocata-lysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a challenge for energy con-version and storage technology.In this work,a S and N co-doped graphene supported cobalt–nickel sulfide composite catalyst(rGO@SN-CoNi_(2)S_(4))was synthesized simply via a one-step hydrothermal method.The as-synthesized CoNi_(2)S_(4)particles grew in a mosaic manner inside GO lamellae and were encapsulated with graphene.As a bifunctional catalyst,the r GO@SN-CoNi_(2)S_(4)exhibits excellent electrocatalytic performance under alkaline con-ditions,which only required the overpotential of 142.6 mV(vs.RHE)and 310 m V(vs.RHE)to deliver a current density of 10 mA·cm^(-2) for HER and OER,respectively.The good hydrophilicity of the r GO@SN,the pure phase of bimetallic structure,and the chemical coupling/interaction between the CoNi_(2)S_(4)and the rGO@SN are attributable to be the possible reasons responsible for the higher HER and OER catalytic activities.Additionally,the rGO@SN-CoNi_(2)S_(4)also shows a great potential for serving as an excellent cathode and anode electrolyzer during the water splitting process.展开更多
Carbon quantum dots(CQDs)as a new class of emerging materials have gradually drawn researchers’concern in recent years.In this work,the graphitic CQDs are prepared through a scalable approach,achieving a high yield w...Carbon quantum dots(CQDs)as a new class of emerging materials have gradually drawn researchers’concern in recent years.In this work,the graphitic CQDs are prepared through a scalable approach,achieving a high yield with more than 50%.The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials,manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity.Moreover,the nitrogen-doped reduced graphene oxide(N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO.A novel alkaline aqueous battery assembled by these materials displays a specific energy(50.2 Wh kg^−1),ultrahigh specific power(9.7 kW kg^−1)and excellent cycling performance with 91.5%of capacity retention at 3 A g^−1 for 5000 cycles.The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.展开更多
Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid ma...Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional(3D) core-shell NixSy@MnOxHy heterostructure nanorods grown on nickel foam(NixSy@MnOxHy/NF) as a bifunctional electrocatalyst. NixSy@MnOxHy/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn-S bonds connect the heterostructure interfaces of N ixSy@MnOxHy, leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction(OER). Besides, as an efficient protective shell, the MnOxHy dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, NixSy@MnOxHy/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm^(–2), respectively, along with high stability of 150 h at 100 mA cm^(–2). Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm^(–2), accompanied by excellent stability at 100 mA cm^(–2) for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy.展开更多
Materials featured with self-supported three-dimensional network,hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors.Herein,a novel strategy for the gro...Materials featured with self-supported three-dimensional network,hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors.Herein,a novel strategy for the growth of nickel-cobalt bisulfide(Ni Co S)nanosheets arrays on carbon cloth(CC)as supercapacitor electrodes is reported,involving deposition of two-dimensional metal-organic framework(MOF)precursors on the CC skeletons,conversion of MOF into nickel-cobalt layered double-hydroxide by ion exchange process and formation of Ni Co S by a sulfidation treatment.The Ni Co S nanosheets with rough surface and porous structures are uniformly anchored on the CC skeletons.The unique architecture endows the composite(Ni Co S/CC)with abundant accessible active sites.Besides,robust electrical/mechanical joint between the nanosheets and the substrates is attained,leading to the improved electrochemical performance.Moreover,an asymmetric supercapacitor device is constructed by using Ni Co S/CC and activated carbon as a positive electrode and a negative electrode,respectively.The optimized device exhibits a high specific capacitance,large energy density and long cycle life.The Ni Co S/CC electrode with intriguing electrochemical properties and mechanical flexibility holds great prospect for next-generation wearable devices.展开更多
Years of research have demonstrated that the use of multiple components is essential to the development of a commercial photoelectrode to address specific bottlenecks,such as low charge separation and injection effici...Years of research have demonstrated that the use of multiple components is essential to the development of a commercial photoelectrode to address specific bottlenecks,such as low charge separation and injection efficiency,low carrier diffusion length and lifetime,and poor durability.A facile strategy for the synthesis of multilayered photoanodes from atomic-layer-deposited ultrathin films has enabled a new type of electrode architecture with a total multilayer thickness of 15–17 nm.We illustrate the advantages of this electrode architecture by using nanolayers to address different bottlenecks,thus producing a multilayer photoelectrode with improved interface kinetics and shorter electron transport path,as determined by interface analyses.The photocurrent density was twice that of the bare structure and reached a maximum of 33.3±2.1 mA cm^(−2) at 1.23 VRHE.An integrated overall water-splitting cell consisting of an electrocatalytic NiS cathode and Bi_(2)S_(3)/NiS/NiFeO/TiO_(2) photoanode was used for precious-metal-free seawater splitting at a cell voltage of 1.23 V without degradation.The results and root analyses suggest that the distinctive advantages of the electrode architecture,which are superior to those of bulk bottom-up core–shell and hierarchical architectures,originate from the high density of active sites and nanometer-scale layer thickness,which enhance the suitability for interface-oriented energy conversion processes.展开更多
Searching for efficient and robust non-noble electrocatalysts for hydrogen generation is extremely desirable for future green energy systems.Here, we present the synthesis of integrated Ni-P-S nanosheets array includi...Searching for efficient and robust non-noble electrocatalysts for hydrogen generation is extremely desirable for future green energy systems.Here, we present the synthesis of integrated Ni-P-S nanosheets array including Ni_2P and NiS on nickel foam by a simple simultaneous phosphorization and sulfurization strategy. The resultant sample with optimal composition exhibits superior electrocatalytic performance for hydrogen evolution reaction(HER) in a wide pH range. In alkaline media, it can generate current densities of 10, 20 and 100 mA cm^(-2) at low overpotentials of only-101.9,-142.0 and-207.8 mV with robust durability. It still exhibits high electrocatalytic activities even in acid or neutral media. Such superior electrocatalytic performances can be mainly attributed to the synergistic enhancement of the hybrid Ni-P-S nanosheets array with integration microstructure. The kind of catalyst gives a new insight on achieving efficient and robust hydrogen generation.展开更多
As promising electrode materials for supercapacitors,nickel-cobalt bimetallic sulfides render the advantages of abundant redox reactions and inherently high conductivity.However,in general,unsatisfactory performance o...As promising electrode materials for supercapacitors,nickel-cobalt bimetallic sulfides render the advantages of abundant redox reactions and inherently high conductivity.However,in general,unsatisfactory performance of low specific capacity,low rate capability,and fast capacity loss exist in Ni–Co sulfide electrodes.Herein,we rationally regulate phosphorus-doped nickel–cobalt sulfides(P-NCS)to enhance the electrochemical performance by gas–solid phosphorization.Moreover,carbon nanotubes(CNTs)as conductive additives are added to improve the cycle stability and conductivity and form the composite P-NCS/C/CNT.According to density functional theory,more electrons near the Fermi surface of P-NCS are demonstrated notionally than those of simple CoNi2S4.Electrochemical results manifest that P-NCS/C/CNT exhibits superior electrochemical performance,e.g.,high specific capacity(932.0 C·g^(-1)at 1 A·g^(-1)),remarkable rate capability(capacity retention ratio of 69.1%at 20 A·g^(-1)),and lower charge transfer resistance.More importantly,the flexible hybrid asymmetric supercapacitor is assembled using P-NCS/C/CNT and activated carbon,which renders an energy density of 34.875 W·h∙kg^(-1)at a power density of 375 W∙kg^(-1).These results show that as-prepared P-NCS/C/CNT demonstrates incredible possibility as a battery-type electrode for high-performance supercapacitors.展开更多
A series of bimetallic nickel cobalt sulfides with hierarchical micro/nano architectures were fabricated via a facile synthesis strategy of bimetallic micro/nano structure precursor construction-anion exchange via sol...A series of bimetallic nickel cobalt sulfides with hierarchical micro/nano architectures were fabricated via a facile synthesis strategy of bimetallic micro/nano structure precursor construction-anion exchange via solvothermal method. Among the nickel cobalt sulfides with different Ni/Co contents, the coral-like Ni1.01Co1.99S4 (Ni/Co, 1/2) delivers ultrafast and stable Na-ion storage performance (350 mAh·g−1 after 1,000 cycles at 1 A·g−1 and 355 mAh·g−1 at 5 A·g−1). The remarkable electrochemical properties can be attributed to the enhanced conductivity by co-existence of bimetallic components, the unique coral-like micro/nanostructure, which could prevent structural collapse and self-aggregation of nanoparticles, and the easily accessibility of electrolyte, and fast Na+ diffusion upon cycling. Detailed kinetics studies by a galvanostatic intermittent titration technique (GITT) reveal the dynamic change of Na+ diffusion upon cycling, and quantitative kinetic analysis indicates the high contribution of pseudocapacitive behavior during charge-discharge processes. Moreover, the ex-situ characterization analysis results further verify the Na-ion storage mechanism based on conversion reaction. This study is expected to provide a feasible design strategy for the bimetallic sulfides materials toward high performance sodium-ion batteries.展开更多
Developing bifunctional electrocatalysts with improved efficiency and stability in overall water splitting is of extreme importance for renewable energy utilization.In this work,an in situ N doping strategy was demons...Developing bifunctional electrocatalysts with improved efficiency and stability in overall water splitting is of extreme importance for renewable energy utilization.In this work,an in situ N doping strategy was demonstrate to boost the efficiency and stability of nickel molybdenum sulfide both in electrocatalytic hydrogen evolution reaction and oxygen evolution reaction.Experimental and theoretical results indicate that such modification offers enriched active sites for electrochemical reaction,and further increases the kinetic driven force of water electrolysis.As a result,the N–NiMoS electrode exhibits a remarkably improved performance with rather low potential of 1.54 V to offer a current density of 10 mA cm;for overall water splitting,which is 130 mV decrease than that of pristine one.In addition,impressive electrochemical stability also reveals a 76.6%preservation of initial current density after 100 h test,which is superior than that of pristine one after 25 h test.Therefore,the potential to enhance the performance of electrocatalysts by as-proposed route promises a valuable way to develop efficient catalysts with enhanced property for electrochemical applications.展开更多
Hydrogen energy plays an important role in clean energy system and is considered the core energy source for future technological development owing to its lightweight nature,high calorific value,and clean combustion pr...Hydrogen energy plays an important role in clean energy system and is considered the core energy source for future technological development owing to its lightweight nature,high calorific value,and clean combustion products.The electrocatalytic conversion of water into hydrogen is considered a highly promising method.An electrocatalyst is indispensable in the electrocatalytic process,and finding an efficient electrocatalyst is essential.However,the current commercial electrocatalysts(such as Pt/C and Ru)are expensive;therefore,there is a need to find an inexpensive and efficient electrocatalyst with high stability,corrosion resistance,and high electrocatalytic efficiency.In this study,we developed a cost-effective bifunctional electrocatalyst by incorporating molybdenum into nickel sulfide(Ni_(3)S_(2))and subsequently tailoring its structure to achieve a one-dimensional(1D)needle-like configuration.The hydrogen production efficiency of nickel sulfide was improved by changing the ratio of Mo doping.By analyzing the electrochemical performance of different Mo-doped catalysts,we found that the Ni_(3)S_(2)-Mo-0.1 electrocatalyst exhibited the best electrocatalytic effect in 1 M KOH;at a current density of 10 mA cm^(-2),it exhibited overpotentials of 120 and 279 mV for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),respectively;at a higher current density of 100 mA cm^(-2),the HER and OER overpotentials were 396 and 495 mV,respectively.Furthermore,this electrocatalyst can be used in a two-electrode water-splitting system.Finally,we thoroughly investigated the mechanism of the overall water splitting of this electrocatalyst,providing valuable insights for future hydrogen production via overall-water-splitting.展开更多
Nickel cobalt bimetallic heterogeneous sulfides are attractive battery-type materials for electrochemical energy storage.However,the precise synthesis of electrode materials that integrate highly efficient ions/electr...Nickel cobalt bimetallic heterogeneous sulfides are attractive battery-type materials for electrochemical energy storage.However,the precise synthesis of electrode materials that integrate highly efficient ions/electrons diffusion with abundant charge transfer channels has always been challenging.Herein,an effective and concise controllable hydrothermal approach is reported for tuning the crystalline and integrated structures of MOF-derived bimetallic sulfides to accelerate the charge transfer kinetics,and thus enabling rich Faradaic redox reaction.The as-obtained low-crystalline heterogeneous NiCo_(2)S_(4)/Co_(3)S_(4)nanocages exhibit a high specific capacity(1023 C/g at 1 A/g),remarkable rate performance(560 C/g at 10A/g),and outstanding cycling stability(89.6%retention after 5000 cycles).Furthermore,hybrid supercapacitors fabricated with NiCo_(2)S_(4)/Co_(3)S_(4)and nitrogen-doped reduced graphene oxide display an outstanding energy density of 40.8 Wh/kg at a power density of 806.3 W/kg,with an excellent capacity retention of 88.3%after 10000 charge-discharge cycles.展开更多
Electrocatalytic hydrogen production in alkaline media is extensively adopted in industry. Unfortunately, further performance improvement is severely impeded by the retarded kinetics, which requires the fine regulatio...Electrocatalytic hydrogen production in alkaline media is extensively adopted in industry. Unfortunately, further performance improvement is severely impeded by the retarded kinetics, which requires the fine regulation of water dissociation, hydrogen recombination, and hydroxyl desorption. Herein, we develop a multi-interface engineering strategy to make an elaborate balance for the alkaline hydrogen evolution reaction (HER) kinetics. The graphene cross-linked three-phase nickel sulfide (NiS-NiS_(2)-Ni_(3)S_(4)) polymorph foam (G-NNNF) was constructed through hydrothermal sulfidation of graphene wrapped nickel foam as a three-dimensional (3D) scaffold template. The G-NNNF exhibits superior catalytic activity toward HER in alkaline electrolyte, which only requires an overpotential of 68 mV to drive 10 mA·cm^(−2) and is better than most of the recently reported metal sulfides catalysts. Density functional theory (DFT) calculations verify the interfaces between nickel sulfides (NiS/NiS_(2)-Ni_(3)S_(4)) and cross-linked graphene can endow the electrocatalyst with preferable hydrogen adsorption as well as metallic nature. In addition, the electron transfer from Ni_(3)S_(4)/NiS_(2) to NiS results in the electron accumulation on NiS and the hole accumulation on Ni_(3)S_(4)/NiS_(2), respectively. The electron accumulation on NiS favors the optimization of the H* adsorption, whereas the hole accumulation on Ni_(3)S_(4) is beneficial for the adsorption of H_(2)O. The work about multi-interface collaboration pushes forward the frontier of excellent polymorph catalysts design.展开更多
Mulitipe stoichiometric ratio of two-dimensional(2D)transition metal dichalcogenides(TMDCs)attracted considerable interest for their unique chemical and physical properties.Here we developed a chemical vapor depositio...Mulitipe stoichiometric ratio of two-dimensional(2D)transition metal dichalcogenides(TMDCs)attracted considerable interest for their unique chemical and physical properties.Here we developed a chemical vapor deposition(CVD)method to controllably synthesize ultrathin NiS and NiS2 nanoplates.By tuning the growth temperature and the amounts of the sulfur powder,2D nonlayered NiS and NiS2 nanoplates can be selectively prepared with the thickness of 2.0 and 7.0 nm,respectively.X-ray diffraction(XRD)and transmission electron microscopy(TEM)characterization reveal that the 2D NiS and N1S2 nanoplates are high-quality single crystals in the hexagonal and cubic phase,respectively.Electrical transport studies show that electrical conductivities of the 2D NiS and N1S2 nanoplates are as high as 4.6 x 10^5 and 6.3 x 10^5 S·m^-1,respectively.The electrical results demonstrate that the synthesized metallic NiS and NiS2 could serve as good electrodes in 2D electronics.展开更多
Electrochemical upgrading of biomass ethanol to value-added chemicals is promising for sustainable society.Here,we synthesize defective Ni_(3)S_(2) nanowires(NWs),which show high activity towards electrochemical oxida...Electrochemical upgrading of biomass ethanol to value-added chemicals is promising for sustainable society.Here,we synthesize defective Ni_(3)S_(2) nanowires(NWs),which show high activity towards electrochemical oxidation of ethanol to acetate.The Ni_(3)S_(2) NWs are formed by the oriented attachment mechanism,and rich defects are introduced during the growth.A low onset potential of 1.31 V and high mass activity of 8,716 mA·mgNi^(-1) at 1.5 V are achieved using the synthesized Ni_(3)S_(2) NWs toward the ethanol electro-oxidation,which are better than the Ni(OH)2 NWs and the Ni_(3)S_(2) nanoparticles(NPs).And the selectivity for the acetate generation is ca.99%.The high activity of Ni_(3)S_(2) NWs is attributed to the easier oxidation of Ni(II)to the catalytically active Ni(III)species with the promotion from S component and rich defects.These results demonstrate that the defective NWs can be synthesized by the oriented attachment method and the defective Ni_(3)S_(2) NWs structure as the efficient nonnoble metal electrocatalysts for oxidative upgrading of ethanol.展开更多
The NiS;nanosheet array on Ni foil(NiS2/NF)was prepared using an in situ growth strategy and sulfidation method and was used as the cathode of lithium sulfur battery.The unique nanostructure of the NiS;nanosheet array...The NiS;nanosheet array on Ni foil(NiS2/NF)was prepared using an in situ growth strategy and sulfidation method and was used as the cathode of lithium sulfur battery.The unique nanostructure of the NiS;nanosheet array can provide abundant active sites for the adsorption and chemical action of polysulfides.Compared with the sulfur powder coated pure NF(pure NF-S)for lithium sulfur battery,the sulfur powder coated NiS_(2)/NF(NiS_(2)/NF-S)electrode exhibits superior electrochemical performance.Specifically,the NiS_(2)/NF-S delivered a high reversible capacity of 1007.5 m Ah g^(-1) at a current density of 0.1 C(1 C=1675 mA g^(-1))and kept 74.5% of the initial capacity at 1.0 C after 200 cycles,indicating the great promise of NiS_(2)/NF-S as the cathode of lithium sulfur battery.In addition,the NiS_(2)/NF-S electrode also showed satisfactory electrochemical performance when used as the cathode for sodium sulfur battery.展开更多
基金the support by the National Natural Science Foundation of China(11972219 and 11902185)the support of Shanghai Sailing Program(19YF1415100)+2 种基金the Young Elite Scientist Sponsorship Program by CAST(2019QNRC001)the support of the National Natural Science Foundation of China(52090022)the Natural Science Foundation for Distinguished Young Scholars of Hebei Province(E2020203085)。
文摘The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have investigated the fundamental reaction behaviors of nickel sulfide(NixSy)as lithium-ion battery anodes by in-situ TEM.We find that Ni_(3)S_(2)is the electrochemically stable phase,which appears in the first cycle of the NixSyanode.From the second cycle,conversion between Ni_(3)S_(2)and Li_(2)S/Ni is the dominant electrochemical reaction.In lithiation,the NixSynanoparticles evolve into a mixture of Ni nanocrystals embedded in Li_(2)S matrix,which form a porous structure upon full lithiation,and with the recrystallization of the Ni_(3)S_(2)phase in delithiation,a compact and interconnected network is built.Structural stability in cycles is susceptible to particle size and substrate restraint.Carbon substrate can certainly improve the tolerance for size-dependent pulverization of NixSynanoparticles.When NixSynanoparticle exceeds the critical size value,the morphology of the particle is no longer well maintained even under the constraints of the carbon substrate.This work deepens the understanding of electrochemical reaction behavior of conversiontype materials and helps to rational design of high-energy density battery anodes.
基金financial supports from the National Natural Science Foundation of China (52004155,51690164, and 51805321)the China Postdoctoral Science Foundation (2020M681261)the Science and Technology Commission of Shanghai Municipality (19XD1401600 and 19010500300)。
文摘An electrocatalyst with heterogeneous nanostructure, especially the hierarchical one, generally shows a more competitive activity than that of its single-component counterparts for oxygen evolution reaction(OER), due to the synergistically enhanced kinetics on enriched active sites and reconfigured electronic band structure. Here this work introduces hierarchical heterostructures into a NiMo@NiS/MoS_(2)@Ni_(2)S_(2)/MoO_(x)(NiMoS) composite by one-pot controlled moderative sulfidation. The optimal solvent composition and addition of NaOH enable NiMoS to own loose and porous structures, smaller nanoparticle sizes, optimal phase composition and chemical states of elements, improving the OER activity of NiMoS. To achieve current densities of 50 and 100 mA cm^(-1), small overpotentials of 275 and 306 mV are required respectively, together with a minor Tafel slope of 58 mV dec^(-1), which outperforms most reported sulfide catalysts and IrO_(2). The synergistic effects in the hierarchical heterostructures expose more active sites,adjust the electronic band structure, and enable the fast charge transfer kinetics, which construct an optimized local coordination environment for high OER electrocatalytic activity. Furthermore, the hierarchical heterostructures suppress the distinct lowering of electrical conductivity and collapse of pristine structures resulted from the metal oxidation and synchronous S leaching during OER, yielding competitive catalytic stability.
文摘The availability of polymetallic ores is getting leaner in grade and is larger but inferior in volumes than in the past, making the extraction of copper, nickel and other non-ferrous metals metallurgically more difficult to produce. The standard technologies, including enrichment and concentration, do not provide methods for obtaining monometallic concentrates and high extraction of metals into the commercial product. Pyrometallurgical processing of large volumes of poor raw materials is not economical and is complicated from the technological point of view. Conditions of chemical enrichment of poor natural materials have been studied with the use of technology of salt exchange leaching. The main impurity in sulfide ores of nonferrous metals is iron present in the forms of pyrite and pyrrhotite and the properties of chemical enrichment for nickel in pyrite concentrates has been investigated in this work. On the basis of thermodynamic analysis carried out with the use of Potential-pH Pourbaix’s Diagrams, it has been established that, with the use of nickel salt, it is possible to leach iron sulfides from ores. Based on the study of the mechanism and kinetics of the process of dissolution of iron sulfides with nickel salts, it was established that during the dissolution, the chemical composition and thermodynamic characteristics of the dissolved iron sulfides change—the residues from leaching are enriched with iron sulfides that are rich in sulfur and also result with elemental sulfur formation. Enrichment of leaching residues with sulfide iron with increased sulfur content and formation on the surface of nickel sulfide leads to increase of diffusional resistances and the process is limited by the velocity of mass transfer. To increase the velocity of the process and completeness of the reaction, it is necessary to activate the process, in particular, by grinding the solid phase.
基金the National Natural Science Foundation of China(Nos.51302079,51702138 and 51403193)the Natural Science Foundation of Hunan Province(No.2017JJ1008)the Key Research and Development Program of Hunan Province of China(No.2018GK2031)。
文摘Supercapacitors are favorable energy storage devices in the field of emerging energy technologies with high power density,excellent cycle stability and environmental benignity.The performance of supercapacitors is definitively influenced by the electrode materials.Nickel sulfides have attracted extensive interest in recent years due to their specific merits for supercapacitor application.However,the distribution of electrochemically active sites critically limits their electrochemical performance.Notable improvements have been achieved through various strategies such as building synergetic structures with conductive substrates,enhancing the active sites by nanocrystallization and constructing nanohybrid architecture with other electrode materials.This article overviews the progress in the reasonable design and preparation of nickel sulfides and their composite electrodes combined with various bifunctional electric double-layer capacitor(EDLC)-based substances(e.g.,graphene,hollow carbon)and pseudocapacitive materials(e.g.,transition-metal oxides,sulfides,nitrides).Moreover,the corresponding electrochemical performances,reaction mechanisms,emerging challenges and future perspectives are briefly discussed and summarized.
基金financially supported by Guangdong Basic and Applied Basic Research Foundation (Nos. 2020A1515110473 and 2019A1515110528)。
文摘Designing highly active and stable electrocata-lysts for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a challenge for energy con-version and storage technology.In this work,a S and N co-doped graphene supported cobalt–nickel sulfide composite catalyst(rGO@SN-CoNi_(2)S_(4))was synthesized simply via a one-step hydrothermal method.The as-synthesized CoNi_(2)S_(4)particles grew in a mosaic manner inside GO lamellae and were encapsulated with graphene.As a bifunctional catalyst,the r GO@SN-CoNi_(2)S_(4)exhibits excellent electrocatalytic performance under alkaline con-ditions,which only required the overpotential of 142.6 mV(vs.RHE)and 310 m V(vs.RHE)to deliver a current density of 10 mA·cm^(-2) for HER and OER,respectively.The good hydrophilicity of the r GO@SN,the pure phase of bimetallic structure,and the chemical coupling/interaction between the CoNi_(2)S_(4)and the rGO@SN are attributable to be the possible reasons responsible for the higher HER and OER catalytic activities.Additionally,the rGO@SN-CoNi_(2)S_(4)also shows a great potential for serving as an excellent cathode and anode electrolyzer during the water splitting process.
基金financially supported by National Natural Science Foundation of China(21601057)Hunan Provincial Natural Science Foundation of China(2018JJ3116)Excellent Youth Fund of Hunan Provincial Education Department(18B298)
文摘Carbon quantum dots(CQDs)as a new class of emerging materials have gradually drawn researchers’concern in recent years.In this work,the graphitic CQDs are prepared through a scalable approach,achieving a high yield with more than 50%.The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials,manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity.Moreover,the nitrogen-doped reduced graphene oxide(N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO.A novel alkaline aqueous battery assembled by these materials displays a specific energy(50.2 Wh kg^−1),ultrahigh specific power(9.7 kW kg^−1)and excellent cycling performance with 91.5%of capacity retention at 3 A g^−1 for 5000 cycles.The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2021A1515110859)the Research Fund Program of Key Laboratory of Fuel Cell Technology of Guangdong Province+2 种基金the Natural Sciences and Engineering Research Council of Canada(NSERC)Institut National de la Recherche Scientifique(INRS)。
文摘Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional(3D) core-shell NixSy@MnOxHy heterostructure nanorods grown on nickel foam(NixSy@MnOxHy/NF) as a bifunctional electrocatalyst. NixSy@MnOxHy/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn-S bonds connect the heterostructure interfaces of N ixSy@MnOxHy, leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction(OER). Besides, as an efficient protective shell, the MnOxHy dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, NixSy@MnOxHy/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm^(–2), respectively, along with high stability of 150 h at 100 mA cm^(–2). Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm^(–2), accompanied by excellent stability at 100 mA cm^(–2) for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy.
基金supported by NSFC(21801200,U1905215,U1705251 and 51872220)Innovative Research Funds of SKLWUT(2017-ZD-4)Fundamental Research Funds for the Central Universities(WUT:2019IVB050)。
文摘Materials featured with self-supported three-dimensional network,hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors.Herein,a novel strategy for the growth of nickel-cobalt bisulfide(Ni Co S)nanosheets arrays on carbon cloth(CC)as supercapacitor electrodes is reported,involving deposition of two-dimensional metal-organic framework(MOF)precursors on the CC skeletons,conversion of MOF into nickel-cobalt layered double-hydroxide by ion exchange process and formation of Ni Co S by a sulfidation treatment.The Ni Co S nanosheets with rough surface and porous structures are uniformly anchored on the CC skeletons.The unique architecture endows the composite(Ni Co S/CC)with abundant accessible active sites.Besides,robust electrical/mechanical joint between the nanosheets and the substrates is attained,leading to the improved electrochemical performance.Moreover,an asymmetric supercapacitor device is constructed by using Ni Co S/CC and activated carbon as a positive electrode and a negative electrode,respectively.The optimized device exhibits a high specific capacitance,large energy density and long cycle life.The Ni Co S/CC electrode with intriguing electrochemical properties and mechanical flexibility holds great prospect for next-generation wearable devices.
基金We are grateful to Prof.Hong H.Lee for the valuable and in-depth conversations related to this study.This study was financially supported by the National Research Foundation of Korea(2021R1A2C1012735)Open access funding provided by Shanghai Jiao Tong University
文摘Years of research have demonstrated that the use of multiple components is essential to the development of a commercial photoelectrode to address specific bottlenecks,such as low charge separation and injection efficiency,low carrier diffusion length and lifetime,and poor durability.A facile strategy for the synthesis of multilayered photoanodes from atomic-layer-deposited ultrathin films has enabled a new type of electrode architecture with a total multilayer thickness of 15–17 nm.We illustrate the advantages of this electrode architecture by using nanolayers to address different bottlenecks,thus producing a multilayer photoelectrode with improved interface kinetics and shorter electron transport path,as determined by interface analyses.The photocurrent density was twice that of the bare structure and reached a maximum of 33.3±2.1 mA cm^(−2) at 1.23 VRHE.An integrated overall water-splitting cell consisting of an electrocatalytic NiS cathode and Bi_(2)S_(3)/NiS/NiFeO/TiO_(2) photoanode was used for precious-metal-free seawater splitting at a cell voltage of 1.23 V without degradation.The results and root analyses suggest that the distinctive advantages of the electrode architecture,which are superior to those of bulk bottom-up core–shell and hierarchical architectures,originate from the high density of active sites and nanometer-scale layer thickness,which enhance the suitability for interface-oriented energy conversion processes.
基金supported by the National Natural Science Foundation of China(21522602, 51672082, 91534202)the International Science and Technology Cooperation Program of China (2015DFA51220)+2 种基金the Research Project of Chinese Ministry of Education(113026A)the Program for Shanghai Youth Top-notch Talentthe Fundamental Research Funds for the Central Universities
文摘Searching for efficient and robust non-noble electrocatalysts for hydrogen generation is extremely desirable for future green energy systems.Here, we present the synthesis of integrated Ni-P-S nanosheets array including Ni_2P and NiS on nickel foam by a simple simultaneous phosphorization and sulfurization strategy. The resultant sample with optimal composition exhibits superior electrocatalytic performance for hydrogen evolution reaction(HER) in a wide pH range. In alkaline media, it can generate current densities of 10, 20 and 100 mA cm^(-2) at low overpotentials of only-101.9,-142.0 and-207.8 mV with robust durability. It still exhibits high electrocatalytic activities even in acid or neutral media. Such superior electrocatalytic performances can be mainly attributed to the synergistic enhancement of the hybrid Ni-P-S nanosheets array with integration microstructure. The kind of catalyst gives a new insight on achieving efficient and robust hydrogen generation.
基金supported by the National Natural Science Foundation of China(Grant No.522702045)。
文摘As promising electrode materials for supercapacitors,nickel-cobalt bimetallic sulfides render the advantages of abundant redox reactions and inherently high conductivity.However,in general,unsatisfactory performance of low specific capacity,low rate capability,and fast capacity loss exist in Ni–Co sulfide electrodes.Herein,we rationally regulate phosphorus-doped nickel–cobalt sulfides(P-NCS)to enhance the electrochemical performance by gas–solid phosphorization.Moreover,carbon nanotubes(CNTs)as conductive additives are added to improve the cycle stability and conductivity and form the composite P-NCS/C/CNT.According to density functional theory,more electrons near the Fermi surface of P-NCS are demonstrated notionally than those of simple CoNi2S4.Electrochemical results manifest that P-NCS/C/CNT exhibits superior electrochemical performance,e.g.,high specific capacity(932.0 C·g^(-1)at 1 A·g^(-1)),remarkable rate capability(capacity retention ratio of 69.1%at 20 A·g^(-1)),and lower charge transfer resistance.More importantly,the flexible hybrid asymmetric supercapacitor is assembled using P-NCS/C/CNT and activated carbon,which renders an energy density of 34.875 W·h∙kg^(-1)at a power density of 375 W∙kg^(-1).These results show that as-prepared P-NCS/C/CNT demonstrates incredible possibility as a battery-type electrode for high-performance supercapacitors.
基金This work was supported by the Shandong Provincial Natural Science Foundation (Nos. ZR2020QB123, ZR2020QB108, and ZR2019MEM030)the National Natural Science Foundation of China (Nos. 51972180, 22071135, and 51572134)+2 种基金Academy of Sciences large apparatus United Fund of China (No. U1832187)Key Research & Development Project of Shandong Province (No. 2019GGX102070)the Program for Scientific Research Innovation Team in Colleges and Universities of Jinan (No. 2018GXRC006).
文摘A series of bimetallic nickel cobalt sulfides with hierarchical micro/nano architectures were fabricated via a facile synthesis strategy of bimetallic micro/nano structure precursor construction-anion exchange via solvothermal method. Among the nickel cobalt sulfides with different Ni/Co contents, the coral-like Ni1.01Co1.99S4 (Ni/Co, 1/2) delivers ultrafast and stable Na-ion storage performance (350 mAh·g−1 after 1,000 cycles at 1 A·g−1 and 355 mAh·g−1 at 5 A·g−1). The remarkable electrochemical properties can be attributed to the enhanced conductivity by co-existence of bimetallic components, the unique coral-like micro/nanostructure, which could prevent structural collapse and self-aggregation of nanoparticles, and the easily accessibility of electrolyte, and fast Na+ diffusion upon cycling. Detailed kinetics studies by a galvanostatic intermittent titration technique (GITT) reveal the dynamic change of Na+ diffusion upon cycling, and quantitative kinetic analysis indicates the high contribution of pseudocapacitive behavior during charge-discharge processes. Moreover, the ex-situ characterization analysis results further verify the Na-ion storage mechanism based on conversion reaction. This study is expected to provide a feasible design strategy for the bimetallic sulfides materials toward high performance sodium-ion batteries.
基金financially supported by the National Key Research Program(No.2016YFD0400601)the National Natural Science Foundation of China(Nos.91634118 and 11575228)
文摘Developing bifunctional electrocatalysts with improved efficiency and stability in overall water splitting is of extreme importance for renewable energy utilization.In this work,an in situ N doping strategy was demonstrate to boost the efficiency and stability of nickel molybdenum sulfide both in electrocatalytic hydrogen evolution reaction and oxygen evolution reaction.Experimental and theoretical results indicate that such modification offers enriched active sites for electrochemical reaction,and further increases the kinetic driven force of water electrolysis.As a result,the N–NiMoS electrode exhibits a remarkably improved performance with rather low potential of 1.54 V to offer a current density of 10 mA cm;for overall water splitting,which is 130 mV decrease than that of pristine one.In addition,impressive electrochemical stability also reveals a 76.6%preservation of initial current density after 100 h test,which is superior than that of pristine one after 25 h test.Therefore,the potential to enhance the performance of electrocatalysts by as-proposed route promises a valuable way to develop efficient catalysts with enhanced property for electrochemical applications.
基金supported by the National Natural Science Foundation of China(No.51802177)the Joint Funds of the National Natural Science Foundation of China(No.U22A20140)State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘Hydrogen energy plays an important role in clean energy system and is considered the core energy source for future technological development owing to its lightweight nature,high calorific value,and clean combustion products.The electrocatalytic conversion of water into hydrogen is considered a highly promising method.An electrocatalyst is indispensable in the electrocatalytic process,and finding an efficient electrocatalyst is essential.However,the current commercial electrocatalysts(such as Pt/C and Ru)are expensive;therefore,there is a need to find an inexpensive and efficient electrocatalyst with high stability,corrosion resistance,and high electrocatalytic efficiency.In this study,we developed a cost-effective bifunctional electrocatalyst by incorporating molybdenum into nickel sulfide(Ni_(3)S_(2))and subsequently tailoring its structure to achieve a one-dimensional(1D)needle-like configuration.The hydrogen production efficiency of nickel sulfide was improved by changing the ratio of Mo doping.By analyzing the electrochemical performance of different Mo-doped catalysts,we found that the Ni_(3)S_(2)-Mo-0.1 electrocatalyst exhibited the best electrocatalytic effect in 1 M KOH;at a current density of 10 mA cm^(-2),it exhibited overpotentials of 120 and 279 mV for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),respectively;at a higher current density of 100 mA cm^(-2),the HER and OER overpotentials were 396 and 495 mV,respectively.Furthermore,this electrocatalyst can be used in a two-electrode water-splitting system.Finally,we thoroughly investigated the mechanism of the overall water splitting of this electrocatalyst,providing valuable insights for future hydrogen production via overall-water-splitting.
基金supported by National Natural Science Foundation of China(Nos.52173255 and 52125202)the Opening Project of the Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials(No.JSKC20021)PAPD of Jiangsu and the Collaborative Innovation Center for Advanced Micro/nanomaterials and Equipment(Co-constructed by Jiangsu Province and Ministry of Education)。
文摘Nickel cobalt bimetallic heterogeneous sulfides are attractive battery-type materials for electrochemical energy storage.However,the precise synthesis of electrode materials that integrate highly efficient ions/electrons diffusion with abundant charge transfer channels has always been challenging.Herein,an effective and concise controllable hydrothermal approach is reported for tuning the crystalline and integrated structures of MOF-derived bimetallic sulfides to accelerate the charge transfer kinetics,and thus enabling rich Faradaic redox reaction.The as-obtained low-crystalline heterogeneous NiCo_(2)S_(4)/Co_(3)S_(4)nanocages exhibit a high specific capacity(1023 C/g at 1 A/g),remarkable rate performance(560 C/g at 10A/g),and outstanding cycling stability(89.6%retention after 5000 cycles).Furthermore,hybrid supercapacitors fabricated with NiCo_(2)S_(4)/Co_(3)S_(4)and nitrogen-doped reduced graphene oxide display an outstanding energy density of 40.8 Wh/kg at a power density of 806.3 W/kg,with an excellent capacity retention of 88.3%after 10000 charge-discharge cycles.
基金This work was supported by the National Key Research and Development Program of China(No.2017YFB0405400)Shandong Provincial Natural Science Foundation(Nos.ZR2019BB025 and ZR2018ZC0842)+2 种基金the Project of“20 items of University”of Jinan(No.2018GXRC031)the National Natural Science Foundation of China(Nos.21976014,U1930402 and 22071172)the generous computer time from TianHe2-JK Supercomputer Center.
文摘Electrocatalytic hydrogen production in alkaline media is extensively adopted in industry. Unfortunately, further performance improvement is severely impeded by the retarded kinetics, which requires the fine regulation of water dissociation, hydrogen recombination, and hydroxyl desorption. Herein, we develop a multi-interface engineering strategy to make an elaborate balance for the alkaline hydrogen evolution reaction (HER) kinetics. The graphene cross-linked three-phase nickel sulfide (NiS-NiS_(2)-Ni_(3)S_(4)) polymorph foam (G-NNNF) was constructed through hydrothermal sulfidation of graphene wrapped nickel foam as a three-dimensional (3D) scaffold template. The G-NNNF exhibits superior catalytic activity toward HER in alkaline electrolyte, which only requires an overpotential of 68 mV to drive 10 mA·cm^(−2) and is better than most of the recently reported metal sulfides catalysts. Density functional theory (DFT) calculations verify the interfaces between nickel sulfides (NiS/NiS_(2)-Ni_(3)S_(4)) and cross-linked graphene can endow the electrocatalyst with preferable hydrogen adsorption as well as metallic nature. In addition, the electron transfer from Ni_(3)S_(4)/NiS_(2) to NiS results in the electron accumulation on NiS and the hole accumulation on Ni_(3)S_(4)/NiS_(2), respectively. The electron accumulation on NiS favors the optimization of the H* adsorption, whereas the hole accumulation on Ni_(3)S_(4) is beneficial for the adsorption of H_(2)O. The work about multi-interface collaboration pushes forward the frontier of excellent polymorph catalysts design.
基金We acknowledge the support from the National Natural Science Foundation of China(No.51872086)the Hunan Key Laboratory of Two-Dimensional Materials(No.2018TP1010)+1 种基金the Strategic Priority Research Program of Chinese Academy of Science(No.XDB30000000)the National Key Research and Development Program of Ministry of Science and Technology(No.2018YFA0703704).
文摘Mulitipe stoichiometric ratio of two-dimensional(2D)transition metal dichalcogenides(TMDCs)attracted considerable interest for their unique chemical and physical properties.Here we developed a chemical vapor deposition(CVD)method to controllably synthesize ultrathin NiS and NiS2 nanoplates.By tuning the growth temperature and the amounts of the sulfur powder,2D nonlayered NiS and NiS2 nanoplates can be selectively prepared with the thickness of 2.0 and 7.0 nm,respectively.X-ray diffraction(XRD)and transmission electron microscopy(TEM)characterization reveal that the 2D NiS and N1S2 nanoplates are high-quality single crystals in the hexagonal and cubic phase,respectively.Electrical transport studies show that electrical conductivities of the 2D NiS and N1S2 nanoplates are as high as 4.6 x 10^5 and 6.3 x 10^5 S·m^-1,respectively.The electrical results demonstrate that the synthesized metallic NiS and NiS2 could serve as good electrodes in 2D electronics.
基金This work was supported by the National Natural Science Foundation of China(No.21971008)the Fundamental Research Funds for the Central Universities(buctrc201916,buctrc201823).
文摘Electrochemical upgrading of biomass ethanol to value-added chemicals is promising for sustainable society.Here,we synthesize defective Ni_(3)S_(2) nanowires(NWs),which show high activity towards electrochemical oxidation of ethanol to acetate.The Ni_(3)S_(2) NWs are formed by the oriented attachment mechanism,and rich defects are introduced during the growth.A low onset potential of 1.31 V and high mass activity of 8,716 mA·mgNi^(-1) at 1.5 V are achieved using the synthesized Ni_(3)S_(2) NWs toward the ethanol electro-oxidation,which are better than the Ni(OH)2 NWs and the Ni_(3)S_(2) nanoparticles(NPs).And the selectivity for the acetate generation is ca.99%.The high activity of Ni_(3)S_(2) NWs is attributed to the easier oxidation of Ni(II)to the catalytically active Ni(III)species with the promotion from S component and rich defects.These results demonstrate that the defective NWs can be synthesized by the oriented attachment method and the defective Ni_(3)S_(2) NWs structure as the efficient nonnoble metal electrocatalysts for oxidative upgrading of ethanol.
基金supported by the National Natural Science Foundation of China(Grant No.21673051)the Department of Science and Technology of Guangdong Province,China(Grant No.2019A050510043)。
文摘The NiS;nanosheet array on Ni foil(NiS2/NF)was prepared using an in situ growth strategy and sulfidation method and was used as the cathode of lithium sulfur battery.The unique nanostructure of the NiS;nanosheet array can provide abundant active sites for the adsorption and chemical action of polysulfides.Compared with the sulfur powder coated pure NF(pure NF-S)for lithium sulfur battery,the sulfur powder coated NiS_(2)/NF(NiS_(2)/NF-S)electrode exhibits superior electrochemical performance.Specifically,the NiS_(2)/NF-S delivered a high reversible capacity of 1007.5 m Ah g^(-1) at a current density of 0.1 C(1 C=1675 mA g^(-1))and kept 74.5% of the initial capacity at 1.0 C after 200 cycles,indicating the great promise of NiS_(2)/NF-S as the cathode of lithium sulfur battery.In addition,the NiS_(2)/NF-S electrode also showed satisfactory electrochemical performance when used as the cathode for sodium sulfur battery.
