The kinetic competition between electron-hole recombination and water oxidation is a key limitation for the development of efficient solar water splitting materials. In this study, we present a solution for solving th...The kinetic competition between electron-hole recombination and water oxidation is a key limitation for the development of efficient solar water splitting materials. In this study, we present a solution for solving this challenge by constructing a quantum dot-intercalated nanostructure. For the first time, we show the interlayer charge of the intercalated nanostructure can significantly inhibit the electron-hole recombination in photocatalysis. For Bi2WO6 quantum dots （QDs） intercalated in a montmorillonite （MMT） nanostructure as an example, the average lifetime of the photogenerated charge carriers was increased from 3.06 μs to 18.8 Ds by constructing the intercalated nanostructure. The increased lifetime markedly improved the photocatalytic performance of Bi2WO6 both in solar water oxidation and environmental purification. This work not oMy provides a method to produce QD-intercalated ultrathin nanostructures but also a general route to design efficient semiconductor-based photoconversion materials for solar fuel generation and environmental purification.展开更多
Single-and dual-atom catalysts(SACs and DACs)on single-layer graphene are widely investigated for a wide range of electrochemical reactions.However,the effect of van der Waals interactions on the activity of these cat...Single-and dual-atom catalysts(SACs and DACs)on single-layer graphene are widely investigated for a wide range of electrochemical reactions.However,the effect of van der Waals interactions on the activity of these catalysts has not been investigated through systematic high-throughput screening.Here we introduce the concept of van der Waals interactions through a double-layer DAC structure which has axial d orbital modification towards enhanced CO_(2) reduction reaction(CO_(2)RR),hydrogen evolution reaction(HER),oxygen reduction reaction(ORR),and oxygen evolution reaction(OER).We applied density functional theory(DFT)to screen 3d,4d,and 5d transition metals supported by double-layer nitrogen-doped graphene,denoted as M2N8.We sought catalysts with high thermodynamic and electrochemical stabilities along with low overpotentials for CO_(2)RR,ORR,OER,or HER.We find that HER can take place inside the van der Waals gap of V2N8 and Co2N8 leading to overpotentials of 0.10 and 0.16 V.Moreover,ORR and OER can take place on the surface of Fe2N8 and Ir2N8,respectively,leading to overpotentials of 0.39 and 0.37 V.DFT predicts a CO_(2)RR overpotential of 0.85 V towards CO on the surface of Co2N8 along with the HER overpotential of 0.16 V inside the van der Waals gap of Co2N8 towards the production of syngas(CO+H_(2)).This paper provides fundamental insights into the design of advanced multi-layer catalysts by applying the concept of van der Waals interactions for electrochemistry at room temperature.展开更多
The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of stability.We demonstrate herein that chemical dopants on sulfur-doped graphene(S-G)can be utilized to stabi...The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of stability.We demonstrate herein that chemical dopants on sulfur-doped graphene(S-G)can be utilized to stabilize ultrafine(sub-2 nm)Au_(25)(PET)18 clusters to enable stable nitrogen reduction reaction(NRR)without significant structural degradation.The Au_(25)@S-G exhibits an ammonia yield rate of 27.5μgNH_(3)·mgAu^(-1)·h^(-1)at-0.5 V with faradic efficiency of 2.3%.More importantly,the anchored clusters preserve~80%NRR activity after four days of continuous operation,a significant improvement over the 15%remaining ammonia production rate for clusters loaded on undoped graphene tested under the same conditions.Isotope labeling experiments confirmed the ammonia was a direct reaction product of N2 feeding gas instead of other chemical contaminations.Ex-situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy of post-reaction catalysts reveal that the sulfur dopant plays a critical role in stabilizing the chemical state and coordination environment of Au atoms in clusters.Further ReaxFF molecular dynamics(RMD)simulation confirmed the strong interaction between Au nanoclusters(NCs)and S-G.This substrate-anchoring process could serve as an effective strategy to study ultrafine nanoclusters’electrocatalytic behavior while minimizing the destruction of the under-coordinated surface motif under harsh electrochemical reaction conditions.展开更多
Twin boundary(TB)engineering has been widely applied to enhance the strength and plasticity of metals and alloys,but is rarely adopted in thermoelectric(TE)semiconductors.Our previous first-principles results showed t...Twin boundary(TB)engineering has been widely applied to enhance the strength and plasticity of metals and alloys,but is rarely adopted in thermoelectric(TE)semiconductors.Our previous first-principles results showed that nanotwins can strengthen TE Indium Antimony(InSb)through In–Sb covalent bond rearrangement at the TBs.Herein,we further show that shear-induced deformation twinning enhances plasticity of InSb.We demonstrate this by employing large-scale molecular dynamics(MD)to follow the shear stress response of flawless single-crystal InSb along various slip systems.We observed that the maximum shear strain for the (111)[112] slip system can be up to 0.85 due to shear-induced deformation twinning.We attribute this deformation twinning to the“catching bond”involving breaking and re-formation of In–Sb bond in InSb.This finding opens up a strategy to increase the plasticity of TE InSb by deformation twinning,which is expected to be implemented in other isotypicⅢ–V semiconductors with zinc blende structure.展开更多
Inorganic semiconductor α-Ag_(2)S exhibits a metal-like ductile behavior at room temperature,but the origin of this high ductility has not been fully explored yet.Based on density function theory simulations on the i...Inorganic semiconductor α-Ag_(2)S exhibits a metal-like ductile behavior at room temperature,but the origin of this high ductility has not been fully explored yet.Based on density function theory simulations on the intrinsic mechanical properties of α-Ag_(2)S,its underlying ductile mechanism is attributed to the following three factors:(i)the low ideal shear strength and multiple slip pathways under pressure,(ii)easy movement of Ag–S octagon framework without breaking Ag−S bonds,and(iii)a metallic Ag−Ag bond forms which suppresses the Ag-S frameworks from slipping and holds them together.The easy slip pathways(or easy rearrangement of atoms without breaking bonds)in α-Ag_(2)S provide insight into the understanding of the plastic deformation mechanism of ductile semiconductor materials,which is beneficial for devising and developing flexible semiconductor materials and electronic devices.展开更多
α-MgAgSb based thermoelectric(TE)device attracts much attention for its commercial application because it shows an extremely high conversion efficiency of ~8.5% under a temperature difference of 225 K.However,the mec...α-MgAgSb based thermoelectric(TE)device attracts much attention for its commercial application because it shows an extremely high conversion efficiency of ~8.5% under a temperature difference of 225 K.However,the mechanical behavior of α-MgAgSb is another serious consideration for its engineering applications.Here,we apply density functional theory(DFT)simulations to examine the intrinsic mechanical properties of all three MgAgSb phases,including elastic properties,shear-stress-shear-strain relationships,deformation and failure mechanism under ideal shear and biaxial shear conditions.We find that the ideal shear strength of α-MgAgSb is 3.25 GPa along the most plausible(100)<010>slip system.This strength is higher than that of β-MgAgSb(0.80 GPa)and lower than that of γ-MgAgSb(3.43 GPa).The failure of α-MgAgSb arises from the stretching and breakage of MgeSb bond α-MgAgSb under pure shear load,while it arises from the softening of MgeAg bond and the breakage of AgeSb bond under biaxial shear load.This suggests that the deformation mechanism changes significantly under different loading conditions.展开更多
基金This work was financially supported by the National Basic Research Program of China （Grant Nos. 2010CB933503, 2013CB933203）, the National Natural Science Foundation of China （Grant Nos. 51102262, 51272269）, and the Science Foundation for Youth Scholars of the State Key Laboratory of High Performance Ceramics and Superfine Microstructures （Grant No. SKL201204）.
文摘The kinetic competition between electron-hole recombination and water oxidation is a key limitation for the development of efficient solar water splitting materials. In this study, we present a solution for solving this challenge by constructing a quantum dot-intercalated nanostructure. For the first time, we show the interlayer charge of the intercalated nanostructure can significantly inhibit the electron-hole recombination in photocatalysis. For Bi2WO6 quantum dots （QDs） intercalated in a montmorillonite （MMT） nanostructure as an example, the average lifetime of the photogenerated charge carriers was increased from 3.06 μs to 18.8 Ds by constructing the intercalated nanostructure. The increased lifetime markedly improved the photocatalytic performance of Bi2WO6 both in solar water oxidation and environmental purification. This work not oMy provides a method to produce QD-intercalated ultrathin nanostructures but also a general route to design efficient semiconductor-based photoconversion materials for solar fuel generation and environmental purification.
基金William A.Goddard III thanks the US National Science Foundation(No.CBET-2311117)for supportGuanHua Chen acknowledges financial support from the General Research Fund(Grant No.17309620)Research Grants Council(RGC:T23-713/22-R).
文摘Single-and dual-atom catalysts(SACs and DACs)on single-layer graphene are widely investigated for a wide range of electrochemical reactions.However,the effect of van der Waals interactions on the activity of these catalysts has not been investigated through systematic high-throughput screening.Here we introduce the concept of van der Waals interactions through a double-layer DAC structure which has axial d orbital modification towards enhanced CO_(2) reduction reaction(CO_(2)RR),hydrogen evolution reaction(HER),oxygen reduction reaction(ORR),and oxygen evolution reaction(OER).We applied density functional theory(DFT)to screen 3d,4d,and 5d transition metals supported by double-layer nitrogen-doped graphene,denoted as M2N8.We sought catalysts with high thermodynamic and electrochemical stabilities along with low overpotentials for CO_(2)RR,ORR,OER,or HER.We find that HER can take place inside the van der Waals gap of V2N8 and Co2N8 leading to overpotentials of 0.10 and 0.16 V.Moreover,ORR and OER can take place on the surface of Fe2N8 and Ir2N8,respectively,leading to overpotentials of 0.39 and 0.37 V.DFT predicts a CO_(2)RR overpotential of 0.85 V towards CO on the surface of Co2N8 along with the HER overpotential of 0.16 V inside the van der Waals gap of Co2N8 towards the production of syngas(CO+H_(2)).This paper provides fundamental insights into the design of advanced multi-layer catalysts by applying the concept of van der Waals interactions for electrochemistry at room temperature.
基金This research was supported by the Director,Office of Science,Office of Basic Energy Sciences,Chemical Sciences,Geosciences,&Biosciences Division,of the US Department of Energy under Contract DEAC02-05CH11231,FWP CH030201(Catalysis Research Program)The Advanced Light Source was supported by the Director,Office of Science,Office of Basic Energy Sciences,of the US Department of Energy under Contract DE-AC02-05CH11231+1 种基金This work made use of the facilities at the NMR Facility,College of Chemistry,University of California,Berkeley.Inductively coupled plasma optical emission spectrometry was supported by the Microanalytical Facility,College of Chemistry,University of California,BerkeleyPart of this material(WAG,TC)was based on work performed by the Liquid Sunlight Alliance,which was supported by the US Department of Energy,Office of Science,Office of Basic Energy Sciences,Fuels from Sunlight Hub under Award Number DE-SC0021266.
文摘The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of stability.We demonstrate herein that chemical dopants on sulfur-doped graphene(S-G)can be utilized to stabilize ultrafine(sub-2 nm)Au_(25)(PET)18 clusters to enable stable nitrogen reduction reaction(NRR)without significant structural degradation.The Au_(25)@S-G exhibits an ammonia yield rate of 27.5μgNH_(3)·mgAu^(-1)·h^(-1)at-0.5 V with faradic efficiency of 2.3%.More importantly,the anchored clusters preserve~80%NRR activity after four days of continuous operation,a significant improvement over the 15%remaining ammonia production rate for clusters loaded on undoped graphene tested under the same conditions.Isotope labeling experiments confirmed the ammonia was a direct reaction product of N2 feeding gas instead of other chemical contaminations.Ex-situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy of post-reaction catalysts reveal that the sulfur dopant plays a critical role in stabilizing the chemical state and coordination environment of Au atoms in clusters.Further ReaxFF molecular dynamics(RMD)simulation confirmed the strong interaction between Au nanoclusters(NCs)and S-G.This substrate-anchoring process could serve as an effective strategy to study ultrafine nanoclusters’electrocatalytic behavior while minimizing the destruction of the under-coordinated surface motif under harsh electrochemical reaction conditions.
基金This work was supported by the National Natural Science Foundation of China(number 52022074,51972253,and 51772231)the Natural Science Foundation of Hubei Province(2020CFB202)+1 种基金the Fundamental Research Funds for the Central Universities(WUT:2020III031 and 2020IB001)We acknowledge Sandia National Laboratories for distributing the open-source MD software LAMMPS。
文摘Twin boundary(TB)engineering has been widely applied to enhance the strength and plasticity of metals and alloys,but is rarely adopted in thermoelectric(TE)semiconductors.Our previous first-principles results showed that nanotwins can strengthen TE Indium Antimony(InSb)through In–Sb covalent bond rearrangement at the TBs.Herein,we further show that shear-induced deformation twinning enhances plasticity of InSb.We demonstrate this by employing large-scale molecular dynamics(MD)to follow the shear stress response of flawless single-crystal InSb along various slip systems.We observed that the maximum shear strain for the (111)[112] slip system can be up to 0.85 due to shear-induced deformation twinning.We attribute this deformation twinning to the“catching bond”involving breaking and re-formation of In–Sb bond in InSb.This finding opens up a strategy to increase the plasticity of TE InSb by deformation twinning,which is expected to be implemented in other isotypicⅢ–V semiconductors with zinc blende structure.
基金This work is partially supported by NSF of China under No.51772231the 111 Project of China under Project no.B07040+1 种基金Q.A.was supported by the National Science Foundation CMMI program under grant no.1727428S.M.was thankful for the support by Act 211 Government of the Russian Federation,under No.02.A03.21.0011 and by the Supercomputer Simulation Laboratory of South Ural State University.
文摘Inorganic semiconductor α-Ag_(2)S exhibits a metal-like ductile behavior at room temperature,but the origin of this high ductility has not been fully explored yet.Based on density function theory simulations on the intrinsic mechanical properties of α-Ag_(2)S,its underlying ductile mechanism is attributed to the following three factors:(i)the low ideal shear strength and multiple slip pathways under pressure,(ii)easy movement of Ag–S octagon framework without breaking Ag−S bonds,and(iii)a metallic Ag−Ag bond forms which suppresses the Ag-S frameworks from slipping and holds them together.The easy slip pathways(or easy rearrangement of atoms without breaking bonds)in α-Ag_(2)S provide insight into the understanding of the plastic deformation mechanism of ductile semiconductor materials,which is beneficial for devising and developing flexible semiconductor materials and electronic devices.
基金partially supported by the NSFC(No.51972253)Fundamental Research Funds for the Central Universities(WUT:2019IVA055,2019IB006,2019III208)+1 种基金the support by Act 211 Government of the Russian Federation,under No.02.A03.21.0011by the Supercomputer Simulation Laboratory of South Ural State University[50].
文摘α-MgAgSb based thermoelectric(TE)device attracts much attention for its commercial application because it shows an extremely high conversion efficiency of ~8.5% under a temperature difference of 225 K.However,the mechanical behavior of α-MgAgSb is another serious consideration for its engineering applications.Here,we apply density functional theory(DFT)simulations to examine the intrinsic mechanical properties of all three MgAgSb phases,including elastic properties,shear-stress-shear-strain relationships,deformation and failure mechanism under ideal shear and biaxial shear conditions.We find that the ideal shear strength of α-MgAgSb is 3.25 GPa along the most plausible(100)<010>slip system.This strength is higher than that of β-MgAgSb(0.80 GPa)and lower than that of γ-MgAgSb(3.43 GPa).The failure of α-MgAgSb arises from the stretching and breakage of MgeSb bond α-MgAgSb under pure shear load,while it arises from the softening of MgeAg bond and the breakage of AgeSb bond under biaxial shear load.This suggests that the deformation mechanism changes significantly under different loading conditions.
