We report a transition metal such as manganese doped methylammonium lead halide perovskite(MA(Pb:Mn)I_(3)) solar cell with an power conversion efficiency(PCE) over 20%. The rational design and fabrication of MA(Pb:Mn)...We report a transition metal such as manganese doped methylammonium lead halide perovskite(MA(Pb:Mn)I_(3)) solar cell with an power conversion efficiency(PCE) over 20%. The rational design and fabrication of MA(Pb:Mn)I3 lead to the enhancements of all the photovoltaic parameters. To incorporate Mn can effectively eliminate the trap-assist and bi-molecular recombination. The photo-absorption ability at shorter wavelengths(i.e., less than 500 nm) and charge carrier lifetime can be elaborated. More importantly, the existence of the Mn^(2+)-I~--Mn^(3+)motif contributes for the double exchange effect, giving rise to the charge/spin transport. By a combination of linearly and circularly polarized photo-excitations, we have explicitly determined the role of intrinsic spin–orbit coupling(SOC) in MA(Pb:Mn)I_(3). More dark states are expected to be available for the photocurrent generation. This study may pave the way for deep understandings of transition metals doped hybrid perovskites for highly efficient solar cell applications.展开更多
Constructing and understanding the doping effect of secondary metal in transition metal carbide(TMC)catalysts is pivotal for the design of low-cost hydrogen evolution reaction(HER) electrocatalysts. In this work, we d...Constructing and understanding the doping effect of secondary metal in transition metal carbide(TMC)catalysts is pivotal for the design of low-cost hydrogen evolution reaction(HER) electrocatalysts. In this work, we developed a wet-chemistry strategy for synthesizing Co-modified Fe_5C_2 nanoparticles((Fe_(1-x)Cox)_5C_2 NPs) as highly active HER electrocatalysts in basic solution. The structure of(Fe_(1-x)Cox)_5C_2 NPs was characterized by X-ray diffraction(XRD), extended X-ray absorption fine structure spectra(EXAFS) and scanning/transmission electron microscopy(S/TEM), indicating that the isomorphous substitution of cobalt in the lattice of Fe_5C_2.(Fe_(0.75) Co_(0.25))_5C_2 exhibited the best HER activity(174 mV for j = -10 mA/cm^2). Computational calculation results indicate that Co provides the most active site for HER. X-ray adsorption spectra(XAS) studies further suggested that the electron transfer in Fe–C bonds are enhanced by the substitution of Co, which modulates the hydrogen adsorption on the adjacent electronic-enriched carbon, and therefore promotes HER activity. Our results affirm the design of lowcost bimetallic TMCs based HER catalysts.展开更多
Transition metal carbide （TMC） nanomaterials are promising alternatives to Pt, and are widely used as heterogeneous electrocatalysts for the electrochemical hydrogen evolution reaction （HER）. In this work, a bromi...Transition metal carbide （TMC） nanomaterials are promising alternatives to Pt, and are widely used as heterogeneous electrocatalysts for the electrochemical hydrogen evolution reaction （HER）. In this work, a bromide-induced wet-chemistry strategy to synthesize Co2C nanoparticles （NPs） was developed. Such NPs exhibited high electrocatalytic activity （η= 181 mV for j = -10 mA·cm^-2） and long-term stability （no obvious performance decrease after 4,000 cycles） for the HER. This study will pave the way for the design and fabrication of TMC NPs via a wet- chemistry method, and will have significant impacts on broader areas such as nanocatalysis and energy conversion.展开更多
The unique structure of zero-dimensional(0D)perovskite-analogues has attracted a great amount of research interest in recent years.To date,the current compositional library of 0D perovskites is largely limited to the ...The unique structure of zero-dimensional(0D)perovskite-analogues has attracted a great amount of research interest in recent years.To date,the current compositional library of 0D perovskites is largely limited to the lead-based Cs4PbX6(X=Cl,Br,and I)systems.In this work,we report a new synthesis of lead-free 0D Cs3BiX6(X=Cl,Br)perovskite-analogue nanocrystals(NCs)with a uniform cubic shape.We observe a broad photoluminescence peak centered at 390 nm for the 0D Cs3BiCl6 NCs at low temperatures.This feature originates from a self-trapped exciton mechanism.In situ thermal stability studies show that Cs3BiX6 NCs remain stable upon heating up to 200°C without crystal structural degradation.Moreover,we demonstrate that the Cs3BiX6 NCs can transform into other bismuth-based perovskite-analogues via facile anion exchange or metal ion insertion reactions.Our study presented here offers the opportunity for further understanding of the structure-property relationship of 0D perovskite-analogue materials,leading toward their future optoelectronic applications.展开更多
In-depth understandings of charge carrier transfer dynamics in any artificial catalytic system are of critical importance for the future design of highly efficient photocatalysts.Herein,we synthesized sub-monolayer Zn...In-depth understandings of charge carrier transfer dynamics in any artificial catalytic system are of critical importance for the future design of highly efficient photocatalysts.Herein,we synthesized sub-monolayer ZnSe partial-shell coated CdSe/CdS core/shell quantum dots in a controlled fashion.The ZnSe decorated quantum dots were employed as a model catalyst for photogeneration of H_(2)under light illumination.Both theoretical calculations and experimental results unravel that the growth of ZnSe partial-shell would retard the photogenerated electron transfer,and meanwhile,accelerate the corresponding hole migration process during the H_(2)photogeneration reaction in the artificial photocatalytic system.As such,the performance of the relevant photocatalytic system can be modulated and optimized,and accordingly,a plausible underlying mechanism is rationalized.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 61634001, 11942413, 61974010, and 61904011)the Intergovernmental Cooperation Project, National Key Research and Development Program, Ministry of Science and Technology, China (Grant No. 2019YFE0108400)。
文摘We report a transition metal such as manganese doped methylammonium lead halide perovskite(MA(Pb:Mn)I_(3)) solar cell with an power conversion efficiency(PCE) over 20%. The rational design and fabrication of MA(Pb:Mn)I3 lead to the enhancements of all the photovoltaic parameters. To incorporate Mn can effectively eliminate the trap-assist and bi-molecular recombination. The photo-absorption ability at shorter wavelengths(i.e., less than 500 nm) and charge carrier lifetime can be elaborated. More importantly, the existence of the Mn^(2+)-I~--Mn^(3+)motif contributes for the double exchange effect, giving rise to the charge/spin transport. By a combination of linearly and circularly polarized photo-excitations, we have explicitly determined the role of intrinsic spin–orbit coupling(SOC) in MA(Pb:Mn)I_(3). More dark states are expected to be available for the photocurrent generation. This study may pave the way for deep understandings of transition metals doped hybrid perovskites for highly efficient solar cell applications.
基金supported by the National Natural Science Foundation of China(91645115,21473003,21673273,21473229,21821004,and 91545121)the National Basic Research Program of China(2013CB933100)+4 种基金the financial support of China Postdoctoral Science Foundation(2016M590216)the financial support of China Postdoctoral Science Foundation(2015M580011)National Thousand Young Talents Program of ChinaHundred-Talent Program of Chinese Academy of SciencesShanxi Hundred-Talent Program
文摘Constructing and understanding the doping effect of secondary metal in transition metal carbide(TMC)catalysts is pivotal for the design of low-cost hydrogen evolution reaction(HER) electrocatalysts. In this work, we developed a wet-chemistry strategy for synthesizing Co-modified Fe_5C_2 nanoparticles((Fe_(1-x)Cox)_5C_2 NPs) as highly active HER electrocatalysts in basic solution. The structure of(Fe_(1-x)Cox)_5C_2 NPs was characterized by X-ray diffraction(XRD), extended X-ray absorption fine structure spectra(EXAFS) and scanning/transmission electron microscopy(S/TEM), indicating that the isomorphous substitution of cobalt in the lattice of Fe_5C_2.(Fe_(0.75) Co_(0.25))_5C_2 exhibited the best HER activity(174 mV for j = -10 mA/cm^2). Computational calculation results indicate that Co provides the most active site for HER. X-ray adsorption spectra(XAS) studies further suggested that the electron transfer in Fe–C bonds are enhanced by the substitution of Co, which modulates the hydrogen adsorption on the adjacent electronic-enriched carbon, and therefore promotes HER activity. Our results affirm the design of lowcost bimetallic TMCs based HER catalysts.
基金Acknowledgements This work was financially supported by the National Natural Science Foundation of China （Nos. 21473003 and 21303119） and the National Basic Research Program of China （No. 2013CB933100）. C. Y. acknowledges the financial support of China Postdoctoral Science Foundation （No. 2015M580011）. XAS analysis was performed at the Beijing Synchrotron Radiation Fadlity.
文摘Transition metal carbide （TMC） nanomaterials are promising alternatives to Pt, and are widely used as heterogeneous electrocatalysts for the electrochemical hydrogen evolution reaction （HER）. In this work, a bromide-induced wet-chemistry strategy to synthesize Co2C nanoparticles （NPs） was developed. Such NPs exhibited high electrocatalytic activity （η= 181 mV for j = -10 mA·cm^-2） and long-term stability （no obvious performance decrease after 4,000 cycles） for the HER. This study will pave the way for the design and fabrication of TMC NPs via a wet- chemistry method, and will have significant impacts on broader areas such as nanocatalysis and energy conversion.
基金support from Brown University startup funds and the National Science Foundation(OIA-1538893)K.H.-K.is supported by the U.S.Department of Education GAANN research fellowship(P200A150037)。
文摘The unique structure of zero-dimensional(0D)perovskite-analogues has attracted a great amount of research interest in recent years.To date,the current compositional library of 0D perovskites is largely limited to the lead-based Cs4PbX6(X=Cl,Br,and I)systems.In this work,we report a new synthesis of lead-free 0D Cs3BiX6(X=Cl,Br)perovskite-analogue nanocrystals(NCs)with a uniform cubic shape.We observe a broad photoluminescence peak centered at 390 nm for the 0D Cs3BiCl6 NCs at low temperatures.This feature originates from a self-trapped exciton mechanism.In situ thermal stability studies show that Cs3BiX6 NCs remain stable upon heating up to 200°C without crystal structural degradation.Moreover,we demonstrate that the Cs3BiX6 NCs can transform into other bismuth-based perovskite-analogues via facile anion exchange or metal ion insertion reactions.Our study presented here offers the opportunity for further understanding of the structure-property relationship of 0D perovskite-analogue materials,leading toward their future optoelectronic applications.
文摘In-depth understandings of charge carrier transfer dynamics in any artificial catalytic system are of critical importance for the future design of highly efficient photocatalysts.Herein,we synthesized sub-monolayer ZnSe partial-shell coated CdSe/CdS core/shell quantum dots in a controlled fashion.The ZnSe decorated quantum dots were employed as a model catalyst for photogeneration of H_(2)under light illumination.Both theoretical calculations and experimental results unravel that the growth of ZnSe partial-shell would retard the photogenerated electron transfer,and meanwhile,accelerate the corresponding hole migration process during the H_(2)photogeneration reaction in the artificial photocatalytic system.As such,the performance of the relevant photocatalytic system can be modulated and optimized,and accordingly,a plausible underlying mechanism is rationalized.
