CsPbI_(2)Br perovskite solar cells(PSCs)have drawn tremendous attention due to their suitable bandgap,excellent photothermal stability,and great potential as an ideal candidate for top cells in tandem solar cells.Howe...CsPbI_(2)Br perovskite solar cells(PSCs)have drawn tremendous attention due to their suitable bandgap,excellent photothermal stability,and great potential as an ideal candidate for top cells in tandem solar cells.However,the abundant defects at the buried interface and perovskite layer induce severe charge recombination,resulting in the open-circuit voltage(V_(oc))output and stability much lower than anticipated.Herein,a novel buried interface management strategy is developed to regulate interfacial carrier dynamics and CsPbI_(2)Br defects by introducing ammonium tetrafluoroborate(NH_(4)BF_(4)),thereby resulting in both high CsPbI_(2)Br crystallization and minimized interfacial energy losses.Specifically,NH_(4)^(+)ions could preferentially heal hydroxyl groups on the SnO_(2)surface and balance energy level alignment between SnO_(2)and CsPbI_(2)Br,enhancing charge transport efficiency,while BF_(4)^(-)anions as a quasi-halogen regulate crystal growth of CsPbI_(2)Br,thus reducing perovskite defects.Additionally,it is proved that eliminating hydroxyl groups at the buried interface enhances the iodide migration activation energy of CsPbI_(2)Br for strengthening the phase stability.As a result,the optimized CsPbI_(2)Br PSCs realize a remarkable efficiency of 17.09%and an ultrahigh V_(oc)output of 1.43 V,which is one of the highest values for CsPbI_(2)Br PSCs.展开更多
Among the various types of heterogeneous catalysts,supported metal nanocatalysts(SMNCs)have attracted widespread interest in chemistry and materials science,due to their advantageous features,such as high efficiency,s...Among the various types of heterogeneous catalysts,supported metal nanocatalysts(SMNCs)have attracted widespread interest in chemistry and materials science,due to their advantageous features,such as high efficiency,stability,and reusability for catalytic reactions.However,to obtain well-defined SMNCs and inhibit nanoparticle aggregation,traditional approaches generally involve numerous organic reagents,complex steps,and specialized equipment,thus hindering the practical and large-scale synthesis of SMNCs.In this review,we summarize green and sustainable synthetic methodologies for the assembly of SMNCs,including low temperature pyrolysis and solid-state,surfactant-and reductant-free,and ionic liquid assisted syntheses.The conventional application of SMNCs for electrochemical hydrogen evolution and the corresponding achievements are subsequently discussed.Finally,future perspectives toward the sustainable production of SMNCs are presented.展开更多
---Double data rate synchronous dynamic random access memory （DDR3） has become one of the most mainstream applications in current server and computer systems. In order to quickly set up a system-level signal integri...---Double data rate synchronous dynamic random access memory （DDR3） has become one of the most mainstream applications in current server and computer systems. In order to quickly set up a system-level signal integrity （SI） simulation flow for the DDR3 interface, two system-level SI simulation methodologies, which are board-level S-parameter extraction in the frequency-domain and system-level simulation assumptions in the time domain, are introduced in this paper. By comparing the flow of Speed2000 and PowerSI/Hspice, PowerSI is chosen for the printed circuit board （PCB） board-level S-parameter extraction, while Tektronix oscilloscope （TDS7404） is used for the DDR3 waveform measurement. The lab measurement shows good agreement between simulation and measurement. The study shows that the combination of PowerSI and Hspice is recommended for quick system-level DDR3 SI simulation.展开更多
There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,a...There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.展开更多
Metal sulfides are emerging highly active electrocatalysts for the oxygen evolution reaction(OER),but still suffer from the instability caused by their inevitable reconstruction,especially at industrial-level current ...Metal sulfides are emerging highly active electrocatalysts for the oxygen evolution reaction(OER),but still suffer from the instability caused by their inevitable reconstruction,especially at industrial-level current density.Here,it is discovered that Fe-incorporated Ni3S2 nanowires can deliver extraordinary durability with an ultralow potential degradation rate of 0.006 mV/h in alkaline electrolytes made with fresh water and seawater at a benchmark of 500 mA cm^(-2) while meeting the industrial activity requirement for overpotential less than 300 mV(290 mV).Systematic experiments and theoretical simulations suggest that after forming the S-doped NiFeOOH shell to boost intrinsic activity,Fe incorporation effectivelymitigates the reconstruction of the Ni_(3)S_(2) nanowire core by restraining Ni oxidation and S dissolution,justifying the performance.This work highlights the significance of circumventing reconstruction and provides a strategy to explore practical chalcogenides-based OER electrocatalysts.展开更多
Electrocatalytic CO_(2) reduction(ECR)to high-value fuels and chemicals offers a promising conversion technology for achieving sustainable carbon cycles.In recent years,although great efforts have been made to develop...Electrocatalytic CO_(2) reduction(ECR)to high-value fuels and chemicals offers a promising conversion technology for achieving sustainable carbon cycles.In recent years,although great efforts have been made to develop highefficiency ECR catalysts,challenges remain in achieving high activity and long durability simultaneously.Taking advantage of the adjustable structure,tunable component,and the M–Ch(M¼Sn,In,Bi,etc.,Ch¼S,Se,Te)covalent bonds stabilized metal centers,the p-block metal chalcogenides(PMC)based electrocatalysts have shown great potential in converting CO_(2) into CO or formates.In addition,the unique p-block electron structure can suppress the competitive hydrogen evolution reaction and enhance the adsorption of ECR intermediates.Seeking to systematically understand the structure–activity relationship of PMC-based ECR catalysts,this review summarizes the recent advances in designing PMC electrocatalysts for CO_(2) reduction based on the fundamental aspects of heterogeneous ECR process,including advanced strategies for optimizing the intrinsic activity and improving the loading density of catalytic sites,constructing highly stable catalysts,and tuning product.展开更多
In recent years,two-dimensional metal halide perovskites(MHPs)have attracted increased attention for radiation detection and imaging.Their detection efficiencies are almost comparable to three-dimensional(3D)perovskit...In recent years,two-dimensional metal halide perovskites(MHPs)have attracted increased attention for radiation detection and imaging.Their detection efficiencies are almost comparable to three-dimensional(3D)perovskites.Meanwhile,they demonstrate superior stability to 3D perovskites.The pursuit of high-quality,phase-pure and lead-free two-dimensional MHP materials and large-area fabrication capability for x-ray detectors are among the research hotspots.In this review,we first give a brief introduction of the crystallographic structure,optoelectronic characteristics and preparation methods of high-quality two-dimensional perovskites.In addition,we overview the general working principles of direct and indirect x-ray detection processes and the corresponding performance metrics from the perspective of detection and imaging.Furthermore,we provide a comprehensive discussion on the recent advances in 2D perovskite x-ray detectors and imaging devices.Finally,we pinpoint several major obstacles of 2D x-ray detectors that should be overcome in the near future.展开更多
Perovskite solar cells(PSCs)are promising next-generation photovoltaics due to their unique optoelectronic properties and rapid rise in power conversion efficiency.However,the instability of perovskite materials and d...Perovskite solar cells(PSCs)are promising next-generation photovoltaics due to their unique optoelectronic properties and rapid rise in power conversion efficiency.However,the instability of perovskite materials and devices is a serious obstacle hindering technology commercialization.The quality of perovskite films,which is an important prerequisite for long-term stable PSCs,is determined by the quality of the precursor solution and the post-deposition treatment performed after perovskite formation.Herein,we review the origin of instability of solution-processed PSCs from the perspectives of the precursor solutions and the perovskite films.In addition,we summarize the recent strategies for improving the stability of the perovskite films.Finally,we pinpoint possible approaches to further advance their long-term stability.展开更多
The development of advanced transition metal/nitrogen/carbon-based(M/N/C)catalysts with high activity and extended durability for oxygen reduction reaction(ORR)is critical for platinum-group-metal(PGM)free fuel cells ...The development of advanced transition metal/nitrogen/carbon-based(M/N/C)catalysts with high activity and extended durability for oxygen reduction reaction(ORR)is critical for platinum-group-metal(PGM)free fuel cells but still remains great challenging.In this review,we summarize the recent progress in two typical M/N/C catalysts(atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts and carbon-supported metal nanoparticles with N-doped carbon shells(M@NC))with an emphasis on their potential applications in fuel cells.Starting with understanding the active sites in these two types of catalysts,the representative innovative strategies for enhancing their intrinsic activity and increasing the density of these sites are systematically introduced.The synergistic effects of M-N-C and M@NC are subsequently discussed for those M/N/C catalysts combining both of them.To translate the material-level catalyst performance into high-performance devices,we also include the recent progress in engineering the porous structure and durability of M/N/C catalysts towards efficient performance in fuel cell devices.From the viewpoint of industrial applications,the scale-up cost-effective synthesis of M/N/C catalysts has been lastly briefed.With this knowledge,the challenges and perspectives in designing advanced M/N/C catalysts for potential PGM-free fuel cells are proposed.展开更多
The electrochemical nitrogen reduction reaction(NRR)as an energy-efficient approach for ammonia synthesis is hampered by the low ammonia yield and ambiguous reaction mechanism.Herein,phosphorus-doped carbon nanotube(P...The electrochemical nitrogen reduction reaction(NRR)as an energy-efficient approach for ammonia synthesis is hampered by the low ammonia yield and ambiguous reaction mechanism.Herein,phosphorus-doped carbon nanotube(P-CNTs)is developed as an efficient metal-free electrocatalyst for NRR with a remarkable NH3 yield of 24.4μg·h^−1·mg^−1cat.and partial current density of 0.61 mA·cm^−2.Such superior activity is found to be from P doping and highly conjugated CNTs substrate.Experimental and theoretical investigations discover that the electron-deficient phosphorus sites with Lewis acidity should be genuine active sites and NRR on P-CNTs follows the distal pathway.These findings provide insightful understanding on NRR processes on P-CNTs,opening up opportunities for the rational design of highly-active cost-effective metal-free catalysts for electrochemical ammonia synthesis.展开更多
Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported G...Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported GeSe solar cells rely on a superstrate configuration coupled with a CdS buffer layer,and suffer from unsatisfactory performance.Here we demonstrate that this low efficiency arises from the inevitable high-temperature treatment of p-n junction in superstrate configuration.This results in the diffusion of Cd atoms from CdS layer into GeSe film that introduces detrimental deep trap states inside the bandgap of GeSe(~0.34 eV below conduction band minimum).We adopt therefore a substrate configuration that enables the deposition of CdS atop pre-deposited polycrystalline GeSe film at room temperature,avoiding the Cd diffusion.By optimizing the annealing temperature of complete devices via a highthroughput screening method,the resulting substrate solar cells annealed at 150℃achieve an efficiency of 3.1%,two times that of the best previously reported superstrate GeSe results.展开更多
Alkaline electrochemical water oxidation powered by renewable energies is a promising and environmentally friendly way to produce hydrogen.The industrial water electrolyzers are commonly operated at a high current den...Alkaline electrochemical water oxidation powered by renewable energies is a promising and environmentally friendly way to produce hydrogen.The industrial water electrolyzers are commonly operated at a high current density,calling for abundant and durable active sites to participate in.The rational design of hierarchically structured electrocatalysts is thus essential to industrial water electrolyzers.Herein,we develop a Fe3+induced nanosizing strategy for fabricating such a hierarchical FeCo LDH@Co3O4(LDH:layered double hydroxide)nanostructure array for high-rate water oxidation.Density functional theory(DFT)simulations indicate that the introduction of Fe3+with a small ion radius and high electrical repulsion in the LDH layer distorted the LDH layer,resulting in a reduced nanosheet size and enabling the formation of a hierarchical structure.Such structure cannot be achieved without the participation of Fe3+cations.Benefiting from the significantly enhanced electrochemical surface areas and charge/mass transport due to the hierarchical structure together with the boosted intrinsic activity by electronic modulation of Fe3+,such FeCo LDH@Co3O4 electrode can deliver an industrial-level current density of 1,000 mA·cm-2 at a small overpotential of 392 mV for water oxidation.When assembled in a water electrolyzer,it delivers a current density of 100 mA·cm-2 at a low operation voltage of 1.61 V.Powered by solar light,the electrolyzer demonstrates high solar-to-hydrogen efficiency of 18.15%with stable and reproducible photoresponse.These results provide new insights for constructing hierarchical nanostructures for advanced water oxidation and other diverse applications.展开更多
Summary of main observation and conclusion Colloidal quantum dots(CQDs)are attractive absorber materials for highefficiency photovoltalcs be-cause of their facile solution processing,bandgap tunability due to quant um...Summary of main observation and conclusion Colloidal quantum dots(CQDs)are attractive absorber materials for highefficiency photovoltalcs be-cause of their facile solution processing,bandgap tunability due to quant um confinement effect,and multi-exciton generation.To date,all published performance records for PbS CQDs solar cells have been based on the conventional hot-injection synthesis method.This method usually requires rela-tively strict conditions such as high temperature and the utilty of expensive source material pyrophoric bis(trimethylsilyl)sulfide(TM5-S),limiting the potential for large-scale and low-cost synthesis of Pbs CQDs.Here we report a facile room-temperature synthetic method to produce high-quality Pbs CQDs through inexpensive ionic source materials including Pb NOl2 and Na:5 in the presence of triethanolamine(TEA)as the stabilizing ligand.The PbS CQDs were successfully prepared with an average particle size of about 5 nm.Solar cells based on the as-synthesized PbS CQDs show a preliminary power conversion fficiency of 1.82%.This room-temperature and low-cost synth esis of PbS CQDs will further benefit the development of solution-processed CQD solar cells.展开更多
CONSPECTUS:Tremendous efforts have shown that the precise control of the electrocatalyst structure and morphology can boost their catalytic performance toward diverse important reactions such as oxygen reduction/evolu...CONSPECTUS:Tremendous efforts have shown that the precise control of the electrocatalyst structure and morphology can boost their catalytic performance toward diverse important reactions such as oxygen reduction/evolution reactions(ORR/OER),hydrogen oxidation/evolution reaction(HOR/HER),carbon dioxide/nitrogen reduction reactions(CO_(2)RR/NRR),etc.The physical and chemical confined syntheses have witnessed the success in manipulating catalyst features from macroscopic to atomic level to deal with various application demands.展开更多
Interlayer coupling as a unique feature for two-dimensional(2D)materials may influence their thickness-dependent physical properties,especially the bandgap due to quantum confinement effect.Widely-studied 2D materials...Interlayer coupling as a unique feature for two-dimensional(2D)materials may influence their thickness-dependent physical properties,especially the bandgap due to quantum confinement effect.Widely-studied 2D materials usually possess strong interlayer coupling such as most of transition metal dichalcogenides(TMDs),PtS_(2) and so on.However,2D materials with weak interlayer coupling are rarely referred that mainly focus on ReS_(2),as well as its counterpart ReSe_(2).Here we report a new member of weak interlayer coupling 2D materials,germanium disulfide(GeS_(2)).The interlayer interaction in GeS_(2) is investigated from theory to experiment.By density functional theory calculations,we find that this extraordinarily weak interlayer coupling in GeS_(2) originates from the weak hybridization of interlayer S atoms.Thickness-dependent Raman spectra of GeS_(2) flakes exhibit that the Raman peaks remain unchanged when increasing the thickness;and a small first-order temperature coefficient of-0.00857 cm^(-1)·K^(-1) is obtained from the temperature-dependent Raman spectra.These experimental results further confirm the weak interlayer coupling in GeS_(2).展开更多
The low-temperature electrocatalytic conversion of small molecules has been recognized as a sustainable and environmentally benign strategy for the production of high-value chemicals and transportable fuels.Developing...The low-temperature electrocatalytic conversion of small molecules has been recognized as a sustainable and environmentally benign strategy for the production of high-value chemicals and transportable fuels.Developing efficient electrocatalysts is the core of these electrocatalytic processes.Recently,single atom catalysts(SACs)have achieved great success in various electrocatalytic reactions with predominant catalytic activity such as hydrogen evolution reaction(HER)[1]and oxygen reduction reaction(ORR)[2].However,they encounter considerable challenges for recently emerging complex reactions where multiple reactants,intermediates,and products are involved.The incompetence of SACs towards such complex reactions mainly comes from the single active centers,which cannot be adapted for simultaneous adsorption and coupling of multiple reactants,thus leading to unsatisfactory catalytic performance.To overcome this challenge,researchers have proposed to construct the catalysts with multiple metal atoms as the catalytically active center while keeping them atomically isolated like SACs,for example heterogeneous bimetallic atomic clusters(HBACs).Compared with homogeneous metal clusters containing only one metal element,HBACs have two designable metal centers,offering various specific catalytic sites for simultaneously targeting different elementary steps in electrocatalytic reactions and harnessing the synergistic effect from two catalytic centers.In addition,the orbital interactions between different metal atoms open up the possibility for regulating the electronic structure of the specific metal active sites,thus improving their intrinsic catalytic activity.Thus,such well-defined HBACs hold great potential for improved catalytic activity,selectivity,and durability for complex electrocatalytic reactions compared with SACs and nanoparticle-based heterogeneous catalysts.展开更多
In this paper, spatial channel pairing(SCP) is introduced to coherent combining at the relay in relay networks. Closed-form solution to optimal coherent combining is derived. Given coherent combining, the approximate ...In this paper, spatial channel pairing(SCP) is introduced to coherent combining at the relay in relay networks. Closed-form solution to optimal coherent combining is derived. Given coherent combining, the approximate SCP solution is presented. Finally, an alternating iterative structure is developed. Simulation results and analysis show that, given the symbol error rate and data rate, the proposed alternating iterative structure achieves signal-to-noise ratio gains over existing schemes in maximum ratio combining(MRC) plus matched filter,MRC plus antenna selection, and distributed space-time block coding due to the use of SCP and iterative structure.展开更多
Elemental selenium(Se), as the world’s first but long-neglected photovoltaic material, has regained great interest recently in tandem solar cells as top cells due to its wide bandgap(~1.8 eV), simple, non-toxic and e...Elemental selenium(Se), as the world’s first but long-neglected photovoltaic material, has regained great interest recently in tandem solar cells as top cells due to its wide bandgap(~1.8 eV), simple, non-toxic and earth-abundant composition, and intrinsic environmental stability. In particular, Se possesses the lowest melting point of 217 °C among the photovoltaic absorbers reported so far, endowing Se with a unique advantage of film fabrication by blade coating the Se melt on substrate. However, the poor wettability of Se melt on widely-used photovoltaic functional layers such as TiO_(2) limits its melt processing. Here we introduce a wettability-modification strategy that decreases the contact angle of Se melt on substrate and improves the wettability by appropriately enhancing the heating temperature of molten Se while avoiding Se volatilization. We further reveal the mechanism of the inherent air stability of Se that originates from the high activation energy of oxygen chemisorption on Se(3.21 eV). This enables the realization of compact Se films through melt-based blade coating in ambient air. The resulting Se solar cells exhibit an efficiency of 3.5%. Unencapsulated devices show no efficiency loss after 1,000 h of storage under ambient conditions.展开更多
基金supported by the National Natural Science Foundation of China(22379010,22109166,22309191)Chinese Academy of Sciences。
文摘CsPbI_(2)Br perovskite solar cells(PSCs)have drawn tremendous attention due to their suitable bandgap,excellent photothermal stability,and great potential as an ideal candidate for top cells in tandem solar cells.However,the abundant defects at the buried interface and perovskite layer induce severe charge recombination,resulting in the open-circuit voltage(V_(oc))output and stability much lower than anticipated.Herein,a novel buried interface management strategy is developed to regulate interfacial carrier dynamics and CsPbI_(2)Br defects by introducing ammonium tetrafluoroborate(NH_(4)BF_(4)),thereby resulting in both high CsPbI_(2)Br crystallization and minimized interfacial energy losses.Specifically,NH_(4)^(+)ions could preferentially heal hydroxyl groups on the SnO_(2)surface and balance energy level alignment between SnO_(2)and CsPbI_(2)Br,enhancing charge transport efficiency,while BF_(4)^(-)anions as a quasi-halogen regulate crystal growth of CsPbI_(2)Br,thus reducing perovskite defects.Additionally,it is proved that eliminating hydroxyl groups at the buried interface enhances the iodide migration activation energy of CsPbI_(2)Br for strengthening the phase stability.As a result,the optimized CsPbI_(2)Br PSCs realize a remarkable efficiency of 17.09%and an ultrahigh V_(oc)output of 1.43 V,which is one of the highest values for CsPbI_(2)Br PSCs.
文摘Among the various types of heterogeneous catalysts,supported metal nanocatalysts(SMNCs)have attracted widespread interest in chemistry and materials science,due to their advantageous features,such as high efficiency,stability,and reusability for catalytic reactions.However,to obtain well-defined SMNCs and inhibit nanoparticle aggregation,traditional approaches generally involve numerous organic reagents,complex steps,and specialized equipment,thus hindering the practical and large-scale synthesis of SMNCs.In this review,we summarize green and sustainable synthetic methodologies for the assembly of SMNCs,including low temperature pyrolysis and solid-state,surfactant-and reductant-free,and ionic liquid assisted syntheses.The conventional application of SMNCs for electrochemical hydrogen evolution and the corresponding achievements are subsequently discussed.Finally,future perspectives toward the sustainable production of SMNCs are presented.
基金supported by the National Natural Science Foundation of China under Grant No.61161001
文摘---Double data rate synchronous dynamic random access memory （DDR3） has become one of the most mainstream applications in current server and computer systems. In order to quickly set up a system-level signal integrity （SI） simulation flow for the DDR3 interface, two system-level SI simulation methodologies, which are board-level S-parameter extraction in the frequency-domain and system-level simulation assumptions in the time domain, are introduced in this paper. By comparing the flow of Speed2000 and PowerSI/Hspice, PowerSI is chosen for the printed circuit board （PCB） board-level S-parameter extraction, while Tektronix oscilloscope （TDS7404） is used for the DDR3 waveform measurement. The lab measurement shows good agreement between simulation and measurement. The study shows that the combination of PowerSI and Hspice is recommended for quick system-level DDR3 SI simulation.
文摘There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.
基金the National Key Research and Development Program of China(grant no.2021YFA1501002)National Natural Science Foundation of China(grant nos.22025208,22075300,and 21902162)+1 种基金DNL Cooperation Fund,CAS(grant no.DNL202008)Chinese Academy of Sciences,and Australian Research Council(grant no.DE220100746).
文摘Metal sulfides are emerging highly active electrocatalysts for the oxygen evolution reaction(OER),but still suffer from the instability caused by their inevitable reconstruction,especially at industrial-level current density.Here,it is discovered that Fe-incorporated Ni3S2 nanowires can deliver extraordinary durability with an ultralow potential degradation rate of 0.006 mV/h in alkaline electrolytes made with fresh water and seawater at a benchmark of 500 mA cm^(-2) while meeting the industrial activity requirement for overpotential less than 300 mV(290 mV).Systematic experiments and theoretical simulations suggest that after forming the S-doped NiFeOOH shell to boost intrinsic activity,Fe incorporation effectivelymitigates the reconstruction of the Ni_(3)S_(2) nanowire core by restraining Ni oxidation and S dissolution,justifying the performance.This work highlights the significance of circumventing reconstruction and provides a strategy to explore practical chalcogenides-based OER electrocatalysts.
基金support from the National Key Research and Development Program of China(No.2020YFB1505801)the National Natural Science Foundation of China(Nos.22025208,22075300,and 22102191)the Chinese Academy of Sciences,and the Key Laboratory of Education department of Shaanxi Province(20JS157).
文摘Electrocatalytic CO_(2) reduction(ECR)to high-value fuels and chemicals offers a promising conversion technology for achieving sustainable carbon cycles.In recent years,although great efforts have been made to develop highefficiency ECR catalysts,challenges remain in achieving high activity and long durability simultaneously.Taking advantage of the adjustable structure,tunable component,and the M–Ch(M¼Sn,In,Bi,etc.,Ch¼S,Se,Te)covalent bonds stabilized metal centers,the p-block metal chalcogenides(PMC)based electrocatalysts have shown great potential in converting CO_(2) into CO or formates.In addition,the unique p-block electron structure can suppress the competitive hydrogen evolution reaction and enhance the adsorption of ECR intermediates.Seeking to systematically understand the structure–activity relationship of PMC-based ECR catalysts,this review summarizes the recent advances in designing PMC electrocatalysts for CO_(2) reduction based on the fundamental aspects of heterogeneous ECR process,including advanced strategies for optimizing the intrinsic activity and improving the loading density of catalytic sites,constructing highly stable catalysts,and tuning product.
基金supported by the National Natural Science Foundation of China(22279083)Natural Science Foundation of Guangdong Province(2019A1515010783)+1 种基金Guangzhou Science and Technology Planning Project(202102010443)Songshan Lake Materials Laboratory.
文摘In recent years,two-dimensional metal halide perovskites(MHPs)have attracted increased attention for radiation detection and imaging.Their detection efficiencies are almost comparable to three-dimensional(3D)perovskites.Meanwhile,they demonstrate superior stability to 3D perovskites.The pursuit of high-quality,phase-pure and lead-free two-dimensional MHP materials and large-area fabrication capability for x-ray detectors are among the research hotspots.In this review,we first give a brief introduction of the crystallographic structure,optoelectronic characteristics and preparation methods of high-quality two-dimensional perovskites.In addition,we overview the general working principles of direct and indirect x-ray detection processes and the corresponding performance metrics from the perspective of detection and imaging.Furthermore,we provide a comprehensive discussion on the recent advances in 2D perovskite x-ray detectors and imaging devices.Finally,we pinpoint several major obstacles of 2D x-ray detectors that should be overcome in the near future.
基金supported by the National Natural Science Foundation of China(22109166 and 22279083)the Chinese Academy of Sciences.
文摘Perovskite solar cells(PSCs)are promising next-generation photovoltaics due to their unique optoelectronic properties and rapid rise in power conversion efficiency.However,the instability of perovskite materials and devices is a serious obstacle hindering technology commercialization.The quality of perovskite films,which is an important prerequisite for long-term stable PSCs,is determined by the quality of the precursor solution and the post-deposition treatment performed after perovskite formation.Herein,we review the origin of instability of solution-processed PSCs from the perspectives of the precursor solutions and the perovskite films.In addition,we summarize the recent strategies for improving the stability of the perovskite films.Finally,we pinpoint possible approaches to further advance their long-term stability.
基金This work was supported by the National Key Research and Development Program of China(2016YFB0101202)the National Natural Science Foundation of China(21773263,21972147).
文摘The development of advanced transition metal/nitrogen/carbon-based(M/N/C)catalysts with high activity and extended durability for oxygen reduction reaction(ORR)is critical for platinum-group-metal(PGM)free fuel cells but still remains great challenging.In this review,we summarize the recent progress in two typical M/N/C catalysts(atomically dispersed metal-nitrogen-carbon(M-N-C)catalysts and carbon-supported metal nanoparticles with N-doped carbon shells(M@NC))with an emphasis on their potential applications in fuel cells.Starting with understanding the active sites in these two types of catalysts,the representative innovative strategies for enhancing their intrinsic activity and increasing the density of these sites are systematically introduced.The synergistic effects of M-N-C and M@NC are subsequently discussed for those M/N/C catalysts combining both of them.To translate the material-level catalyst performance into high-performance devices,we also include the recent progress in engineering the porous structure and durability of M/N/C catalysts towards efficient performance in fuel cell devices.From the viewpoint of industrial applications,the scale-up cost-effective synthesis of M/N/C catalysts has been lastly briefed.With this knowledge,the challenges and perspectives in designing advanced M/N/C catalysts for potential PGM-free fuel cells are proposed.
基金We acknowledge the financial supports are from the National Key Research and Development Program of China(No.2016YFB0101202)the National Natural Science Foundation of China(Nos.91645123,21773263).
文摘The electrochemical nitrogen reduction reaction(NRR)as an energy-efficient approach for ammonia synthesis is hampered by the low ammonia yield and ambiguous reaction mechanism.Herein,phosphorus-doped carbon nanotube(P-CNTs)is developed as an efficient metal-free electrocatalyst for NRR with a remarkable NH3 yield of 24.4μg·h^−1·mg^−1cat.and partial current density of 0.61 mA·cm^−2.Such superior activity is found to be from P doping and highly conjugated CNTs substrate.Experimental and theoretical investigations discover that the electron-deficient phosphorus sites with Lewis acidity should be genuine active sites and NRR on P-CNTs follows the distal pathway.These findings provide insightful understanding on NRR processes on P-CNTs,opening up opportunities for the rational design of highly-active cost-effective metal-free catalysts for electrochemical ammonia synthesis.
基金supported by the National Natural Science Foundation of China (21922512 and 21875264)the Youth Innovation Promotion Association CAS (2017050)
文摘Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported GeSe solar cells rely on a superstrate configuration coupled with a CdS buffer layer,and suffer from unsatisfactory performance.Here we demonstrate that this low efficiency arises from the inevitable high-temperature treatment of p-n junction in superstrate configuration.This results in the diffusion of Cd atoms from CdS layer into GeSe film that introduces detrimental deep trap states inside the bandgap of GeSe(~0.34 eV below conduction band minimum).We adopt therefore a substrate configuration that enables the deposition of CdS atop pre-deposited polycrystalline GeSe film at room temperature,avoiding the Cd diffusion.By optimizing the annealing temperature of complete devices via a highthroughput screening method,the resulting substrate solar cells annealed at 150℃achieve an efficiency of 3.1%,two times that of the best previously reported superstrate GeSe results.
基金the financial support from the National Natural Science Foundation of China(Nos.22025208,22075300,and 21902162)the China National Postdoctoral Program for Innovative Talents(No.BX2021319)+1 种基金the DNL Cooperation Fund,CAS(No.DNL202008)the Chinese Academy of Sciences.
文摘Alkaline electrochemical water oxidation powered by renewable energies is a promising and environmentally friendly way to produce hydrogen.The industrial water electrolyzers are commonly operated at a high current density,calling for abundant and durable active sites to participate in.The rational design of hierarchically structured electrocatalysts is thus essential to industrial water electrolyzers.Herein,we develop a Fe3+induced nanosizing strategy for fabricating such a hierarchical FeCo LDH@Co3O4(LDH:layered double hydroxide)nanostructure array for high-rate water oxidation.Density functional theory(DFT)simulations indicate that the introduction of Fe3+with a small ion radius and high electrical repulsion in the LDH layer distorted the LDH layer,resulting in a reduced nanosheet size and enabling the formation of a hierarchical structure.Such structure cannot be achieved without the participation of Fe3+cations.Benefiting from the significantly enhanced electrochemical surface areas and charge/mass transport due to the hierarchical structure together with the boosted intrinsic activity by electronic modulation of Fe3+,such FeCo LDH@Co3O4 electrode can deliver an industrial-level current density of 1,000 mA·cm-2 at a small overpotential of 392 mV for water oxidation.When assembled in a water electrolyzer,it delivers a current density of 100 mA·cm-2 at a low operation voltage of 1.61 V.Powered by solar light,the electrolyzer demonstrates high solar-to-hydrogen efficiency of 18.15%with stable and reproducible photoresponse.These results provide new insights for constructing hierarchical nanostructures for advanced water oxidation and other diverse applications.
基金This work is supported by the National Natural Science Foundation of China(Grants 21573249,21922512,21875264)the Youth Innovation Promotion Association CAS(2017050).
文摘Summary of main observation and conclusion Colloidal quantum dots(CQDs)are attractive absorber materials for highefficiency photovoltalcs be-cause of their facile solution processing,bandgap tunability due to quant um confinement effect,and multi-exciton generation.To date,all published performance records for PbS CQDs solar cells have been based on the conventional hot-injection synthesis method.This method usually requires rela-tively strict conditions such as high temperature and the utilty of expensive source material pyrophoric bis(trimethylsilyl)sulfide(TM5-S),limiting the potential for large-scale and low-cost synthesis of Pbs CQDs.Here we report a facile room-temperature synthetic method to produce high-quality Pbs CQDs through inexpensive ionic source materials including Pb NOl2 and Na:5 in the presence of triethanolamine(TEA)as the stabilizing ligand.The PbS CQDs were successfully prepared with an average particle size of about 5 nm.Solar cells based on the as-synthesized PbS CQDs show a preliminary power conversion fficiency of 1.82%.This room-temperature and low-cost synth esis of PbS CQDs will further benefit the development of solution-processed CQD solar cells.
基金We acknowledge the financial support from the National Key Research and Development Program of China(2020YFB1505801)the National Natural Science Foundation of China(22025208,22075300,and 21773263).
文摘CONSPECTUS:Tremendous efforts have shown that the precise control of the electrocatalyst structure and morphology can boost their catalytic performance toward diverse important reactions such as oxygen reduction/evolution reactions(ORR/OER),hydrogen oxidation/evolution reaction(HOR/HER),carbon dioxide/nitrogen reduction reactions(CO_(2)RR/NRR),etc.The physical and chemical confined syntheses have witnessed the success in manipulating catalyst features from macroscopic to atomic level to deal with various application demands.
基金supported by the National Natural Science Foundation of China(Nos.21922512,21972147,21875264,61725401,and 11964032)the Youth Innovation Promotion Association CAS(No.2017050)the National Natural Science Foundation of Guizhou Province(Nos.KY[2019]060,[2020]123,and trxyDH1905).
文摘Interlayer coupling as a unique feature for two-dimensional(2D)materials may influence their thickness-dependent physical properties,especially the bandgap due to quantum confinement effect.Widely-studied 2D materials usually possess strong interlayer coupling such as most of transition metal dichalcogenides(TMDs),PtS_(2) and so on.However,2D materials with weak interlayer coupling are rarely referred that mainly focus on ReS_(2),as well as its counterpart ReSe_(2).Here we report a new member of weak interlayer coupling 2D materials,germanium disulfide(GeS_(2)).The interlayer interaction in GeS_(2) is investigated from theory to experiment.By density functional theory calculations,we find that this extraordinarily weak interlayer coupling in GeS_(2) originates from the weak hybridization of interlayer S atoms.Thickness-dependent Raman spectra of GeS_(2) flakes exhibit that the Raman peaks remain unchanged when increasing the thickness;and a small first-order temperature coefficient of-0.00857 cm^(-1)·K^(-1) is obtained from the temperature-dependent Raman spectra.These experimental results further confirm the weak interlayer coupling in GeS_(2).
基金This work was supported by the National Key Research and Development Program of China(2020YFB1505801)the National Natural Science Foundation of China(22025208,22075300,and 21773263).
文摘The low-temperature electrocatalytic conversion of small molecules has been recognized as a sustainable and environmentally benign strategy for the production of high-value chemicals and transportable fuels.Developing efficient electrocatalysts is the core of these electrocatalytic processes.Recently,single atom catalysts(SACs)have achieved great success in various electrocatalytic reactions with predominant catalytic activity such as hydrogen evolution reaction(HER)[1]and oxygen reduction reaction(ORR)[2].However,they encounter considerable challenges for recently emerging complex reactions where multiple reactants,intermediates,and products are involved.The incompetence of SACs towards such complex reactions mainly comes from the single active centers,which cannot be adapted for simultaneous adsorption and coupling of multiple reactants,thus leading to unsatisfactory catalytic performance.To overcome this challenge,researchers have proposed to construct the catalysts with multiple metal atoms as the catalytically active center while keeping them atomically isolated like SACs,for example heterogeneous bimetallic atomic clusters(HBACs).Compared with homogeneous metal clusters containing only one metal element,HBACs have two designable metal centers,offering various specific catalytic sites for simultaneously targeting different elementary steps in electrocatalytic reactions and harnessing the synergistic effect from two catalytic centers.In addition,the orbital interactions between different metal atoms open up the possibility for regulating the electronic structure of the specific metal active sites,thus improving their intrinsic catalytic activity.Thus,such well-defined HBACs hold great potential for improved catalytic activity,selectivity,and durability for complex electrocatalytic reactions compared with SACs and nanoparticle-based heterogeneous catalysts.
基金Project supported by the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University,China(No.2013D02)the Open Research Fund of National Key Laboratory of Electromagnetic Environment,China Research Institute of Radiowave Propagation(No.201500013)+2 种基金the National Natural Science Foundation of China(Nos.61271230,61472190,and 61501238)the Research Fund for the Doctoral Program of Higher Education of China(No.20113219120019)the Foundation of Cloud Computing and Big Data for Agriculture and Forestry,China(No.117-612014063)
文摘In this paper, spatial channel pairing(SCP) is introduced to coherent combining at the relay in relay networks. Closed-form solution to optimal coherent combining is derived. Given coherent combining, the approximate SCP solution is presented. Finally, an alternating iterative structure is developed. Simulation results and analysis show that, given the symbol error rate and data rate, the proposed alternating iterative structure achieves signal-to-noise ratio gains over existing schemes in maximum ratio combining(MRC) plus matched filter,MRC plus antenna selection, and distributed space-time block coding due to the use of SCP and iterative structure.
基金supported by the National Science Foundation of China(21922512,21875264)Chinese Postdoctoral Science Foundation(2021MD703865)+1 种基金the Youth Innovation Promotion CAS(Y2021014)。
文摘Elemental selenium(Se), as the world’s first but long-neglected photovoltaic material, has regained great interest recently in tandem solar cells as top cells due to its wide bandgap(~1.8 eV), simple, non-toxic and earth-abundant composition, and intrinsic environmental stability. In particular, Se possesses the lowest melting point of 217 °C among the photovoltaic absorbers reported so far, endowing Se with a unique advantage of film fabrication by blade coating the Se melt on substrate. However, the poor wettability of Se melt on widely-used photovoltaic functional layers such as TiO_(2) limits its melt processing. Here we introduce a wettability-modification strategy that decreases the contact angle of Se melt on substrate and improves the wettability by appropriately enhancing the heating temperature of molten Se while avoiding Se volatilization. We further reveal the mechanism of the inherent air stability of Se that originates from the high activation energy of oxygen chemisorption on Se(3.21 eV). This enables the realization of compact Se films through melt-based blade coating in ambient air. The resulting Se solar cells exhibit an efficiency of 3.5%. Unencapsulated devices show no efficiency loss after 1,000 h of storage under ambient conditions.
