Due to strong synergistic effect of the elements,a series of XEuMnO_(x) ternary oxides(X=Ce,Ni,Co,Sb,Sn,Mo) were synthesized by one-pot co-precipitation method,and composite components were identified and optimized to...Due to strong synergistic effect of the elements,a series of XEuMnO_(x) ternary oxides(X=Ce,Ni,Co,Sb,Sn,Mo) were synthesized by one-pot co-precipitation method,and composite components were identified and optimized to maintain high activity and superior SO_(2)and H_(2)O endurance in selective catalytic reduction of NO_(x)with NH_(3)(NH_(3)-SCR).NO_(x)conversion of CeEuMnO_(x) ternary oxide catalysts attains more than 90% at 100-250℃,and finally achieves 74%under existence of 50×10^(-6)SO_(2) and 10 vol% H_(2)O at 230℃.The facile electron transfer through redox cycle of Mn^(3+)+Ce^(4+)■Mn4++Ce^(3+) and enhanced oxygen mobility can promote formation of more Mn species in high oxidation state and chemisorbed oxygen,accelerating oxidation of NO and the adsorbed NO_(2) formed can facilitate"fast SCR"reaction to improve low-temperature activity.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)study reveals that addition of Ce to EuMnO_(x)catalyst boosts adsorption of NH_(3)and NO_(x)species.NH_(3)species are activated as crucial intermediate(NH_(2))to promote NH_(3)-SCR reaction.This research provides a novel material for practical deNO_(x)application of stationary source combustion flue gas in the future.展开更多
The effective valuation of catalyst supports in the catalytic oxidation makes the contribution to understand the support effect of great interest.Here,the role of active substrate in the performance and stability of C...The effective valuation of catalyst supports in the catalytic oxidation makes the contribution to understand the support effect of great interest.Here,the role of active substrate in the performance and stability of CuFe-Co ternary oxides was studied towards the complete catalytic oxidation of CO.The Cu-Fe-Co oxide thin films were deposited on copper grid mesh(CUGM)using one-step pulsed-spray evaporation chemical vapor deposition method.Crystalline structure and morphology analyses revealed nano-crystallite sizes and do me-top-like morphology.Synergistic effects between Cu,Fe and Co,which affect the surface Cu^2+,Fe^3+,Co^3+and chemisorbed oxygen species(O2 and OH)of thin films over the active support and thus result in better reducibility.The thin film catalysts supported on CUGM exhibited attractive catalytic activity compared to the te rnary oxides supported on ine rt grid mesh at a high gas hourly space velocity.Moreove r,the stability in time-on-stream of the ternary oxides on CUGM was evaluated in the CO oxidation for 30 h.The ad opted deposition strategy ofternary oxides on CUGM presents an excessive amount of adsorbed active oxygen species that play an impo rtant role in the complete CO oxidation.The catalysts supported on CUGM showed better catalytic conve rsion than that on inert grid mesh and some literature-reported noble metal oxides as well as transition metal oxides counterparts,revealing the beneficial effect of the CUGM suppo rt in the improvement of the catalytic performance.展开更多
Fiber-based supercapacitors （FSCs） are new members of the energy storage family. They present excellent flexibility and have promising applications in lightweight, flexible, and wearable devices. One of the existing...Fiber-based supercapacitors （FSCs） are new members of the energy storage family. They present excellent flexibility and have promising applications in lightweight, flexible, and wearable devices. One of the existing challenges of FSCs is enhancing their energy density while retaining the flexibility. We developed a facile and cost-effective method to fabricate a highly capacitive positive electrode based on hierarchical ferric-cobalt-nickel ternary oxide nanowire arrays/graphene fibers and a negative electrode based on polyaniline-derived carbon nanorods/graphene fibers. The elegant microstructures and excellent electrochemical performances of both electrodes enabled us to construct a high- performance flexible asymmetric graphene fiber-based supercapacitor device with an operating voltage of 1.4 V, a specific capacitance up to 61.58 mF.cm-2, and an energy density reaching 16.76 μW·h·cm-2. Moreover, the optimal device presents an outstanding cycling stability with 87.5% initial capacitance retention after 8,000 cycles, and an excellent flexibility with a capacitance retention of 90.9% after 4,000 cycles of repetitive bending.展开更多
Novel zinc-nickel-cobalt ternary oxide nanosheets were successfully synthesized via an easy solvothermal method followed by calcination and were tailored to have different numbers of wrinkles by controlling the vohtrn...Novel zinc-nickel-cobalt ternary oxide nanosheets were successfully synthesized via an easy solvothermal method followed by calcination and were tailored to have different numbers of wrinkles by controlling the vohtrne ratio of the components in the mixed solvent. Nanosheets with more wrinkles yielded a large specific surface area（111.61 m2/g）, which improved their electrochemical properties. The resulting products were characterized using a three-electrode system in 6 mol/L KOH electrolyte solution. With unique structures, the nanosheets with more wrinkles displayed a good capacitive behavior and an excellent specific capacitance retention of 97.18% after 2000 continuous charge-discharge cycles. Considering their high electrochemical performance and simple fabrication, we proposed that these unique zinc-nickel-cobalt oxide nanosheets are promising supercapacitor electrodes for energy storage applications.展开更多
Accelerating the breaking of the nitrogen nonpolar bond(N≡N)is an important factor to improve the effi ciency of the electro-catalytic nitrogen reduction reaction(e-NRR).In this work,polyoxometalates-derived FeMo-bas...Accelerating the breaking of the nitrogen nonpolar bond(N≡N)is an important factor to improve the effi ciency of the electro-catalytic nitrogen reduction reaction(e-NRR).In this work,polyoxometalates-derived FeMo-based ternary oxide materials MoO_(2)-Mo_(4)O_(11)-FeMoO_(4)@X(abbreviated as MoFeO@X,X represents the synthesis temperature of 650,750 and 850℃)were designed and synthesized for e-NRR under ambient conditions.The scanning electron microscopy images of MoFeO@750 show an ellipsoidal-like structure(0.86×0.6μm).The relatively large specifi c surface area,formation of multiple interfaces,together with the synergistic eff ect of iron and molybdenum bimetals,would make MoFeO@X catalyst more easily absorb and activate N_(2)in the e-NRR.Expectedly,the synthesized MoFeO@750 shows an optimal NH_(3)production rate of 16.57μg·h^(−1)·mg cat.^(−1)and Faradaic effi ciency of 12.33%at−0.3 V versus reversible hydrogen electrode(νs.RHE),with outstanding electrochemical and structural stability.展开更多
Transition metal cation ordering is essential for controlling the electrochemical performance of cubic spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO),which is conventionally adjusted by optimizing the high temperature sintering...Transition metal cation ordering is essential for controlling the electrochemical performance of cubic spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO),which is conventionally adjusted by optimizing the high temperature sintering and annealing procedures.In this present work,multiple characterization techniques,including 6,7Li NMR,XRD and HRTEM,have been combined to trace the phase transformation and morphology evolution during synthesis.It has been illustrated that simultaneous formation of LiMn_(2)O_(4)(LMO)and LiNiO_(2)(LNO)binary oxides and their conversion into highly reactive LixNi^(3+)_(y)Mn_(3.5+)_(z)O ternary intermediate is a thermal dynamically difficult but crucial step in the synthesis of LNMO ternary oxide.A new strategy of modifying the intermediates formation pathway from binary mode to ternary mode using thermal regulating agent has been adopted.LNMO synthesized with thermal regulating agent exhibits supreme rate capability,long-cycling performance(even at elevated temperature)and excellent capacity efficiency.At a high rate of 100 C,the assembled battery delivers a discharge capacity of 99 mAh g^(-1).This study provides a way to control the formation pathway of complex oxides using thermal regulating agent.展开更多
The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM) have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based so...The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM) have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based solids with oxides from alkali (Li2O), alkaline earth (CaO), and transition metal groups (WO3 or MnO). The presence of the peroxide (O2-2) active sites on the Li2O2, revealed by Raman spectroscopy, may be the key factor in the enhanced performance of some of the Li2O/MgO catalysts. The high reducibility of the CeO2 catalyst, an important factor in the CO2-OCM catalyst activity, may be enhanced by the presence of manganese oxide species. The manganese oxide species increases oxygen mobility and oxygen vacancies in the CeO2 catalyst. Raman and Fourier Transform Infra Red (FT-IR) spectroscopies revealed the presence of lattice vibrations of metal-oxygen bondings and active sites in which the peaks corresponding to the bulk crystalline structures of Li2O, CaO, WO3 and MnO are detected. The performance of 5%MnO/15%CaO/CeO2 catalyst is the most potential among the CeO2-based catalysts, although lower than the 2%Li2O/MgO catalyst. The 2%Li2O/MgO catalyst showed the most promising C2+ hydrocarbons selectivity and yield at 98.0% and 5.7%, respectively.展开更多
We demonstrate an easy and scalable low-temperature process to convert porous ternary complex metal oxide nanoparticles from solution-synthesized core^shell metal oxide nanopartides by thermal annealing. The final pro...We demonstrate an easy and scalable low-temperature process to convert porous ternary complex metal oxide nanoparticles from solution-synthesized core^shell metal oxide nanopartides by thermal annealing. The final products demonstrate superior electrochemical properties with a large capacity and high stability during fast charging/discharging cycles for potential applications as advanced lithium-ion battery （LIB） electrode materials. In addition, a new breakdown mechanism was observed on these novel electrode materials.展开更多
Zinc-based electrochemistry ene rgy sto rage with high safety and high theoretical capacity is considered to be a competitive candidate to replace lithium-ion batteries.In electrochemical energy storage,multimetal oxi...Zinc-based electrochemistry ene rgy sto rage with high safety and high theoretical capacity is considered to be a competitive candidate to replace lithium-ion batteries.In electrochemical energy storage,multimetal oxide cathode materials can generally provide a wider electrochemical stability window and a higher capacity compared with single metal oxides cathode.Here,a new type of cathode material,MnFe2Co3O8 nanodots/functional graphene sheets,is designed and used for aqueous hybrid Zn-based energy storage.Coupling with a hybrid electrolyte based on zinc sulfate and potassium hydroxide,the asfabricated battery was able to work with a wide electrochemical window of 0.1~1.8 V,showed a high specific capacity of 660 mAh/g,delivered an ultra high energy density of 1135 Wh/kg and a scalable power density of 5754 W/kg(calculated based on the cathode),and displayed a long cycling life of 1000 cycles.These are mainly attributed to the valence charge density distribution in MnFe2Co3O8 nanodots,the good structural strengthening as well as high conductivity of the cathode,and the right electrolyte.Such cathode material also exhibited high electrocatalytic activity for oxygen evolution reaction and thus could be used for constructing a Zn-air battery with an ultrahigh reversible capacity of 9556 mAh/g.展开更多
In this paper,ZnZnFe_(2)O_(4) nanorods were prepared using Zn/Fe metal organic framework(MOF)as precursors,and ZnZnFe_(2)O_(4)/reduced graphene oxide(rGO)was prepared by hydrothermal method.The morphology and composit...In this paper,ZnZnFe_(2)O_(4) nanorods were prepared using Zn/Fe metal organic framework(MOF)as precursors,and ZnZnFe_(2)O_(4)/reduced graphene oxide(rGO)was prepared by hydrothermal method.The morphology and composition of the ZnZnFe_(2)O_(4)/rGO nanocomposite were characterized,and the results showed that the MOF-derived ZnZnFe_(2)O_(4) nanorods are uniformly modified on the surface of rGO.The ZnZnFe_(2)O_(4)/rGO nanocomposite exhibits better SO_(2) gas sensing performance than the single ZnZnFe_(2)O_(4) nanorods at room temperature.The sensing characteristics of single ZnZnFe_(2)O_(4) film sensor,single rGO film sensor and ZnZnFe_(2)O_(4)/rGO composite film sensor at SO_(2)gas concentration(1×10^(-6)-100×10^(-6))were tested.The response of ZnZnFe_(2)O_(4)/rGO composite sensor can reach 18.32%at room temperature.Compared with single ZnZnFe_(2)O_(4) and rGO film sensors,the ZnZnFe_(2)O_(4)/rGO composite sensor has better transient response,good sensitivity and selectivity.In this work,the improvement of the sensor performance is not only due to the p-n heterostructure between ZnZnFe_(2)O_(4) nanorods and rGO nanosheets,but also to the excellent electrical properties of rGO.It provides a new idea for the detection of SO_(2) at room temperature.展开更多
Fe_(2)O_(3)/Co_(3)O_(4)/NiO/NC nanosheets have been successfully prepared via a two-step annealing process of ternary metal coordination polymer. Attributing to the synergistic effects of the multiple metal oxides and...Fe_(2)O_(3)/Co_(3)O_(4)/NiO/NC nanosheets have been successfully prepared via a two-step annealing process of ternary metal coordination polymer. Attributing to the synergistic effects of the multiple metal oxides and the unique 2D nanosheet structure, the improved electrical conductivity and effective electron/ion transfer enables Fe_(2)O_(3)/Co_(3)O_(4)/NiO/NC electrode to exhibit excellent electrochemical properties with outstanding rate capacity and cycling stability. This work may pave the way to construct ternary metal oxide electrode material with an excellent electrochemical performance by introducing multiple metal oxides.展开更多
Hollow ternary metal oxides have shown enormous potential in lithium-ion batteries(LIBs),which is ascribed to their complex chemical composition,abundant active defect sites,and the synergy effect be-tween metals.In t...Hollow ternary metal oxides have shown enormous potential in lithium-ion batteries(LIBs),which is ascribed to their complex chemical composition,abundant active defect sites,and the synergy effect be-tween metals.In this work,we synthesized Mo-doped NiCo_(2)O_(4) porous spheres with yolk-shell structure by using a simple self-templating method.Surprisingly,other than the yolk-shell structure we had ob-tained,the inner core of the yolk-shell was also porous,which could fully enhance the electrolyte infil-tration and promote the transmission of lithium ions(Li+)and electrons(e−).The diameter of the porous core in the yolk-shell sphere was about 530 nm,and the outer shell’s thickness was up to 110 nm.In addition,the unique pores in the core appeared in the diameter of about 85 nm.With this structure,the volume expansion of the anode could be well inhibited during charge/discharge.It exhibited prominent electrochemical performance with high reversible capacity(1338 mA h g^(−1) at 100 mA g^(−1)),satisfactory cycle life(1360 mA h g^(−1) after 200 cycles at 100 mA g^(−1)),and exceptional rate capability(820 mA h g^(−1) at 2000 mA g^(−1))as anode material in LIBs.展开更多
By using the first-principles calculation, we studied the mechanisms of point defects in Y4AI209 （YAM）, a promising ternary oxide with excellent optical and thermal properties. It is found that the predominant nativ...By using the first-principles calculation, we studied the mechanisms of point defects in Y4AI209 （YAM）, a promising ternary oxide with excellent optical and thermal properties. It is found that the predominant native defect species is closely dependent on the chemical potentials of each constituent. In the case of O-rich condition, the oxygen interstitial has the very low defect formation energy, followed by the anti-site defects and AI vacancy; in the case of AI-rich condition, the oxygen vacancy yields the lowest defect formation energy, followed by the anti-site defects and AI interstitial. The present result shows that in all the possible chemical potential ranges, anti-site defects have relatively low defect formation energy and might exist in high concentration in YAM. Furthermore, AIy anti-site has relatively lower defect formation energy than the YAt anti- site throughout. The behaviors of defect complexes under non-stoichiometric condition, such as the AI203 or Y203 excess, are also investigated. The results provide helpful guide to optimize the experimental synthesizing of YAM.展开更多
BiVO4,a promising visible-light responding photocatalyst,has aroused extensive research interest because of inexpensiveness and excellent chemical stability.However,its main drawback is the poor photoinduced charge-tr...BiVO4,a promising visible-light responding photocatalyst,has aroused extensive research interest because of inexpensiveness and excellent chemical stability.However,its main drawback is the poor photoinduced charge-transfer dynamics.Building nanostructures is an effective way to tackle this problem.Herein,we put forward a new method to prepare nanostructured BiVO4 from Bi-based metal-organic frameworks[Bi-MOF(CAU-17)]precursor.The as-prepared material has a rod-like morphology inherited from the Bi-MOF sacrificial template and consists of small nanoparticle as building blocks.Compared with its counterparts prepared by conventional methods,MOF-derived nanostructured BiVO4 shows better light absorption ability,narrower bandgap,and improved electrical conductivity as well as reduced recombination.Consequently,BiVO4 nanostructure demonstrates high photocatalytic activity under visible light towards the degradation of methylene blue.Methylene blue can be degraded up to 90%within 30 min with a reaction rate constant of 0.058 min-1.Moreover,the cycling stability of the catalyst is excellent to withstand unchanged degradation efficiency for at least 5 cycles.展开更多
Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,h...Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,high temperatures are required which inhibit control of pore structure properties including surface area,pore volume,and pore size.Herein,the synthesis of ternary metal oxides Ln_(2)Ti_(2)O_(7)pos-sessing pyrochlore crystal structure is achieved using a novel technique which combines‘soft’and hard colloid templating strategies.The formed materials are of submicron size and composed of∼25-30 nm product‘building blocks’with good chemical and phase stability.The polycrystalline powders have a high specific surface area(up to 70 m^(2)·g^(-1))and pore volume(∼0.35 cm^(3)·g^(-1))which result in a good adsorp-tion capacity(U uptake closing to 60 mg·g^(-1)).Remarkably,the material exhibits a significant portion of mesopores(mainly 10-40 nm)which facilitate fast adsorption of the cations due to high accessibility.The synthetic methodology described herein produces highly homogenous powders and can be applied to other compositions and structures.展开更多
基金Project supported by the National Key R&D Program of China(2019YFC1904100,2019YFC1904102,2019YFC1903900,2019YFC1903902)the National Natural Science Foundation of China(U20A20132,52106180,22076136)+1 种基金the Hebei Province Major Scientific and Technological Achievement Transformation Fund Support Project(2021004012 A)the Central Government Guides the Local Science and Technology Development Fund Project(206Z3702G).
文摘Due to strong synergistic effect of the elements,a series of XEuMnO_(x) ternary oxides(X=Ce,Ni,Co,Sb,Sn,Mo) were synthesized by one-pot co-precipitation method,and composite components were identified and optimized to maintain high activity and superior SO_(2)and H_(2)O endurance in selective catalytic reduction of NO_(x)with NH_(3)(NH_(3)-SCR).NO_(x)conversion of CeEuMnO_(x) ternary oxide catalysts attains more than 90% at 100-250℃,and finally achieves 74%under existence of 50×10^(-6)SO_(2) and 10 vol% H_(2)O at 230℃.The facile electron transfer through redox cycle of Mn^(3+)+Ce^(4+)■Mn4++Ce^(3+) and enhanced oxygen mobility can promote formation of more Mn species in high oxidation state and chemisorbed oxygen,accelerating oxidation of NO and the adsorbed NO_(2) formed can facilitate"fast SCR"reaction to improve low-temperature activity.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)study reveals that addition of Ce to EuMnO_(x)catalyst boosts adsorption of NH_(3)and NO_(x)species.NH_(3)species are activated as crucial intermediate(NH_(2))to promote NH_(3)-SCR reaction.This research provides a novel material for practical deNO_(x)application of stationary source combustion flue gas in the future.
基金financial support from the MOST(No.2017YFA0402800)the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(No.51888103)。
文摘The effective valuation of catalyst supports in the catalytic oxidation makes the contribution to understand the support effect of great interest.Here,the role of active substrate in the performance and stability of CuFe-Co ternary oxides was studied towards the complete catalytic oxidation of CO.The Cu-Fe-Co oxide thin films were deposited on copper grid mesh(CUGM)using one-step pulsed-spray evaporation chemical vapor deposition method.Crystalline structure and morphology analyses revealed nano-crystallite sizes and do me-top-like morphology.Synergistic effects between Cu,Fe and Co,which affect the surface Cu^2+,Fe^3+,Co^3+and chemisorbed oxygen species(O2 and OH)of thin films over the active support and thus result in better reducibility.The thin film catalysts supported on CUGM exhibited attractive catalytic activity compared to the te rnary oxides supported on ine rt grid mesh at a high gas hourly space velocity.Moreove r,the stability in time-on-stream of the ternary oxides on CUGM was evaluated in the CO oxidation for 30 h.The ad opted deposition strategy ofternary oxides on CUGM presents an excessive amount of adsorbed active oxygen species that play an impo rtant role in the complete CO oxidation.The catalysts supported on CUGM showed better catalytic conve rsion than that on inert grid mesh and some literature-reported noble metal oxides as well as transition metal oxides counterparts,revealing the beneficial effect of the CUGM suppo rt in the improvement of the catalytic performance.
基金This work was supported by the National Key R＆D Program of China （No. 2017YFB0406000）, the Key Research Program of Frontier Science of Chinese Academy of Sciences （No. QYZDB-SSW-SLH031）, the Natural Science Foundation of Jiangsu Province, China （Nos. BK20160399 and BK20140392）, the Transformation of Scientific and Technological Achievements in Jiangsu Province （No. BA2016026）, the Postdoctoral Foundation of Jiangsu Province （No. 1601065B）, and the Science and Technology Project of Suzhou, China （Nos. SZS201508, ZXG201428, and ZXG201401）.
文摘Fiber-based supercapacitors （FSCs） are new members of the energy storage family. They present excellent flexibility and have promising applications in lightweight, flexible, and wearable devices. One of the existing challenges of FSCs is enhancing their energy density while retaining the flexibility. We developed a facile and cost-effective method to fabricate a highly capacitive positive electrode based on hierarchical ferric-cobalt-nickel ternary oxide nanowire arrays/graphene fibers and a negative electrode based on polyaniline-derived carbon nanorods/graphene fibers. The elegant microstructures and excellent electrochemical performances of both electrodes enabled us to construct a high- performance flexible asymmetric graphene fiber-based supercapacitor device with an operating voltage of 1.4 V, a specific capacitance up to 61.58 mF.cm-2, and an energy density reaching 16.76 μW·h·cm-2. Moreover, the optimal device presents an outstanding cycling stability with 87.5% initial capacitance retention after 8,000 cycles, and an excellent flexibility with a capacitance retention of 90.9% after 4,000 cycles of repetitive bending.
基金Supported by the National Natural Science Foundation of China（Nos.51372124, 51572134）.
文摘Novel zinc-nickel-cobalt ternary oxide nanosheets were successfully synthesized via an easy solvothermal method followed by calcination and were tailored to have different numbers of wrinkles by controlling the vohtrne ratio of the components in the mixed solvent. Nanosheets with more wrinkles yielded a large specific surface area（111.61 m2/g）, which improved their electrochemical properties. The resulting products were characterized using a three-electrode system in 6 mol/L KOH electrolyte solution. With unique structures, the nanosheets with more wrinkles displayed a good capacitive behavior and an excellent specific capacitance retention of 97.18% after 2000 continuous charge-discharge cycles. Considering their high electrochemical performance and simple fabrication, we proposed that these unique zinc-nickel-cobalt oxide nanosheets are promising supercapacitor electrodes for energy storage applications.
基金supported by Major Research Plan National Natural Science Foundation of China(Grant 92061102)the National Science Foundation of China(22171059)the Outstanding Youth Project of Natural Science Foundation of in Heilongjiang Province(YQ2020B005).
文摘Accelerating the breaking of the nitrogen nonpolar bond(N≡N)is an important factor to improve the effi ciency of the electro-catalytic nitrogen reduction reaction(e-NRR).In this work,polyoxometalates-derived FeMo-based ternary oxide materials MoO_(2)-Mo_(4)O_(11)-FeMoO_(4)@X(abbreviated as MoFeO@X,X represents the synthesis temperature of 650,750 and 850℃)were designed and synthesized for e-NRR under ambient conditions.The scanning electron microscopy images of MoFeO@750 show an ellipsoidal-like structure(0.86×0.6μm).The relatively large specifi c surface area,formation of multiple interfaces,together with the synergistic eff ect of iron and molybdenum bimetals,would make MoFeO@X catalyst more easily absorb and activate N_(2)in the e-NRR.Expectedly,the synthesized MoFeO@750 shows an optimal NH_(3)production rate of 16.57μg·h^(−1)·mg cat.^(−1)and Faradaic effi ciency of 12.33%at−0.3 V versus reversible hydrogen electrode(νs.RHE),with outstanding electrochemical and structural stability.
基金financially supported by the National Natural Science Foundation of China(Grant No.21673065 and 21875057)the Key-Area Research and Development Program of Guangdong Province(No.1934212200002)the Innovation and Entrepreneurship Team Project of Zhuhai(No.ZH01110405170016PWC)。
文摘Transition metal cation ordering is essential for controlling the electrochemical performance of cubic spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO),which is conventionally adjusted by optimizing the high temperature sintering and annealing procedures.In this present work,multiple characterization techniques,including 6,7Li NMR,XRD and HRTEM,have been combined to trace the phase transformation and morphology evolution during synthesis.It has been illustrated that simultaneous formation of LiMn_(2)O_(4)(LMO)and LiNiO_(2)(LNO)binary oxides and their conversion into highly reactive LixNi^(3+)_(y)Mn_(3.5+)_(z)O ternary intermediate is a thermal dynamically difficult but crucial step in the synthesis of LNMO ternary oxide.A new strategy of modifying the intermediates formation pathway from binary mode to ternary mode using thermal regulating agent has been adopted.LNMO synthesized with thermal regulating agent exhibits supreme rate capability,long-cycling performance(even at elevated temperature)and excellent capacity efficiency.At a high rate of 100 C,the assembled battery delivers a discharge capacity of 99 mAh g^(-1).This study provides a way to control the formation pathway of complex oxides using thermal regulating agent.
文摘The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM) have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based solids with oxides from alkali (Li2O), alkaline earth (CaO), and transition metal groups (WO3 or MnO). The presence of the peroxide (O2-2) active sites on the Li2O2, revealed by Raman spectroscopy, may be the key factor in the enhanced performance of some of the Li2O/MgO catalysts. The high reducibility of the CeO2 catalyst, an important factor in the CO2-OCM catalyst activity, may be enhanced by the presence of manganese oxide species. The manganese oxide species increases oxygen mobility and oxygen vacancies in the CeO2 catalyst. Raman and Fourier Transform Infra Red (FT-IR) spectroscopies revealed the presence of lattice vibrations of metal-oxygen bondings and active sites in which the peaks corresponding to the bulk crystalline structures of Li2O, CaO, WO3 and MnO are detected. The performance of 5%MnO/15%CaO/CeO2 catalyst is the most potential among the CeO2-based catalysts, although lower than the 2%Li2O/MgO catalyst. The 2%Li2O/MgO catalyst showed the most promising C2+ hydrocarbons selectivity and yield at 98.0% and 5.7%, respectively.
基金The authors acknowledge the support from the National Science Foundation Electronic and Photonic Materials （No. 1206425） and the startup fund from Iowa State University. Y. W. also thanks the support from the Eastern Scholar Program.
文摘We demonstrate an easy and scalable low-temperature process to convert porous ternary complex metal oxide nanoparticles from solution-synthesized core^shell metal oxide nanopartides by thermal annealing. The final products demonstrate superior electrochemical properties with a large capacity and high stability during fast charging/discharging cycles for potential applications as advanced lithium-ion battery （LIB） electrode materials. In addition, a new breakdown mechanism was observed on these novel electrode materials.
基金supported by the National Nature Science Foundations of China(Nos.21673263 and 21805292)One-Three-Five Strategic Planning of Chinese Academy of Sciences(CAS)the DNL Cooperation Fund,CAS(No.DNL180307)。
文摘Zinc-based electrochemistry ene rgy sto rage with high safety and high theoretical capacity is considered to be a competitive candidate to replace lithium-ion batteries.In electrochemical energy storage,multimetal oxide cathode materials can generally provide a wider electrochemical stability window and a higher capacity compared with single metal oxides cathode.Here,a new type of cathode material,MnFe2Co3O8 nanodots/functional graphene sheets,is designed and used for aqueous hybrid Zn-based energy storage.Coupling with a hybrid electrolyte based on zinc sulfate and potassium hydroxide,the asfabricated battery was able to work with a wide electrochemical window of 0.1~1.8 V,showed a high specific capacity of 660 mAh/g,delivered an ultra high energy density of 1135 Wh/kg and a scalable power density of 5754 W/kg(calculated based on the cathode),and displayed a long cycling life of 1000 cycles.These are mainly attributed to the valence charge density distribution in MnFe2Co3O8 nanodots,the good structural strengthening as well as high conductivity of the cathode,and the right electrolyte.Such cathode material also exhibited high electrocatalytic activity for oxygen evolution reaction and thus could be used for constructing a Zn-air battery with an ultrahigh reversible capacity of 9556 mAh/g.
文摘In this paper,ZnZnFe_(2)O_(4) nanorods were prepared using Zn/Fe metal organic framework(MOF)as precursors,and ZnZnFe_(2)O_(4)/reduced graphene oxide(rGO)was prepared by hydrothermal method.The morphology and composition of the ZnZnFe_(2)O_(4)/rGO nanocomposite were characterized,and the results showed that the MOF-derived ZnZnFe_(2)O_(4) nanorods are uniformly modified on the surface of rGO.The ZnZnFe_(2)O_(4)/rGO nanocomposite exhibits better SO_(2) gas sensing performance than the single ZnZnFe_(2)O_(4) nanorods at room temperature.The sensing characteristics of single ZnZnFe_(2)O_(4) film sensor,single rGO film sensor and ZnZnFe_(2)O_(4)/rGO composite film sensor at SO_(2)gas concentration(1×10^(-6)-100×10^(-6))were tested.The response of ZnZnFe_(2)O_(4)/rGO composite sensor can reach 18.32%at room temperature.Compared with single ZnZnFe_(2)O_(4) and rGO film sensors,the ZnZnFe_(2)O_(4)/rGO composite sensor has better transient response,good sensitivity and selectivity.In this work,the improvement of the sensor performance is not only due to the p-n heterostructure between ZnZnFe_(2)O_(4) nanorods and rGO nanosheets,but also to the excellent electrical properties of rGO.It provides a new idea for the detection of SO_(2) at room temperature.
基金supported by the Natural Science Foundation of Guangdong Province(No.2020A1515010886)the Science and Technology Planning Project of Guangzhou(No.202102010373)。
文摘Fe_(2)O_(3)/Co_(3)O_(4)/NiO/NC nanosheets have been successfully prepared via a two-step annealing process of ternary metal coordination polymer. Attributing to the synergistic effects of the multiple metal oxides and the unique 2D nanosheet structure, the improved electrical conductivity and effective electron/ion transfer enables Fe_(2)O_(3)/Co_(3)O_(4)/NiO/NC electrode to exhibit excellent electrochemical properties with outstanding rate capacity and cycling stability. This work may pave the way to construct ternary metal oxide electrode material with an excellent electrochemical performance by introducing multiple metal oxides.
基金financially supported by the National Natural Science Foundation of China (Nos. 51972180, 51572134 and 41907315)the Key Technology Research and Development Program of Shandong (No. 2019GGX102070)the Program for Scientific Research Innovation Team in Colleges and Universities of Jinan (No. 2018GXRC006)。
文摘Hollow ternary metal oxides have shown enormous potential in lithium-ion batteries(LIBs),which is ascribed to their complex chemical composition,abundant active defect sites,and the synergy effect be-tween metals.In this work,we synthesized Mo-doped NiCo_(2)O_(4) porous spheres with yolk-shell structure by using a simple self-templating method.Surprisingly,other than the yolk-shell structure we had ob-tained,the inner core of the yolk-shell was also porous,which could fully enhance the electrolyte infil-tration and promote the transmission of lithium ions(Li+)and electrons(e−).The diameter of the porous core in the yolk-shell sphere was about 530 nm,and the outer shell’s thickness was up to 110 nm.In addition,the unique pores in the core appeared in the diameter of about 85 nm.With this structure,the volume expansion of the anode could be well inhibited during charge/discharge.It exhibited prominent electrochemical performance with high reversible capacity(1338 mA h g^(−1) at 100 mA g^(−1)),satisfactory cycle life(1360 mA h g^(−1) after 200 cycles at 100 mA g^(−1)),and exceptional rate capability(820 mA h g^(−1) at 2000 mA g^(−1))as anode material in LIBs.
基金supported by the National Natural Science Foundation of China under Grant Nos.50672102,50832008 and 51032006
文摘By using the first-principles calculation, we studied the mechanisms of point defects in Y4AI209 （YAM）, a promising ternary oxide with excellent optical and thermal properties. It is found that the predominant native defect species is closely dependent on the chemical potentials of each constituent. In the case of O-rich condition, the oxygen interstitial has the very low defect formation energy, followed by the anti-site defects and AI vacancy; in the case of AI-rich condition, the oxygen vacancy yields the lowest defect formation energy, followed by the anti-site defects and AI interstitial. The present result shows that in all the possible chemical potential ranges, anti-site defects have relatively low defect formation energy and might exist in high concentration in YAM. Furthermore, AIy anti-site has relatively lower defect formation energy than the YAt anti- site throughout. The behaviors of defect complexes under non-stoichiometric condition, such as the AI203 or Y203 excess, are also investigated. The results provide helpful guide to optimize the experimental synthesizing of YAM.
基金Supported by the National Natural Science Foundation of China(Nos.21671016,51872024,51932001)the China Post-doctoral Science Foundation(No.2019M650849).
文摘BiVO4,a promising visible-light responding photocatalyst,has aroused extensive research interest because of inexpensiveness and excellent chemical stability.However,its main drawback is the poor photoinduced charge-transfer dynamics.Building nanostructures is an effective way to tackle this problem.Herein,we put forward a new method to prepare nanostructured BiVO4 from Bi-based metal-organic frameworks[Bi-MOF(CAU-17)]precursor.The as-prepared material has a rod-like morphology inherited from the Bi-MOF sacrificial template and consists of small nanoparticle as building blocks.Compared with its counterparts prepared by conventional methods,MOF-derived nanostructured BiVO4 shows better light absorption ability,narrower bandgap,and improved electrical conductivity as well as reduced recombination.Consequently,BiVO4 nanostructure demonstrates high photocatalytic activity under visible light towards the degradation of methylene blue.Methylene blue can be degraded up to 90%within 30 min with a reaction rate constant of 0.058 min-1.Moreover,the cycling stability of the catalyst is excellent to withstand unchanged degradation efficiency for at least 5 cycles.
文摘Mesoporous structured metal oxides exhibit many active applications.However,the synthesis of crystalline metal oxides with a ternary composition while maintaining satisfactory pore features is challeng-ing.Typically,high temperatures are required which inhibit control of pore structure properties including surface area,pore volume,and pore size.Herein,the synthesis of ternary metal oxides Ln_(2)Ti_(2)O_(7)pos-sessing pyrochlore crystal structure is achieved using a novel technique which combines‘soft’and hard colloid templating strategies.The formed materials are of submicron size and composed of∼25-30 nm product‘building blocks’with good chemical and phase stability.The polycrystalline powders have a high specific surface area(up to 70 m^(2)·g^(-1))and pore volume(∼0.35 cm^(3)·g^(-1))which result in a good adsorp-tion capacity(U uptake closing to 60 mg·g^(-1)).Remarkably,the material exhibits a significant portion of mesopores(mainly 10-40 nm)which facilitate fast adsorption of the cations due to high accessibility.The synthetic methodology described herein produces highly homogenous powders and can be applied to other compositions and structures.
