In this work,we developed plasmonic photocatalyst composed of Cu Pd alloy nanoparticles supported on Ti N,the optimized Cu_(3)Pd_(2)/Ti N catalyst shows excellent conversion(>96%)and selectivity(>99%)for Heck re...In this work,we developed plasmonic photocatalyst composed of Cu Pd alloy nanoparticles supported on Ti N,the optimized Cu_(3)Pd_(2)/Ti N catalyst shows excellent conversion(>96%)and selectivity(>99%)for Heck reaction at 50℃ under visible light irradiation.By in-situ spectroscopic investigations,we find that visible light excitation could achieve stable metallic Cu species on the surface of Cu Pd alloy nanoparticles,thereby eliminating the inevitable surface oxides of Cu based catalyst.The in-situ formed metallic Cu species under irradiation take advantage of the strong interactions of Cu with visible light,and manifest in the localized surface plasmon resonances(LSPR)photoexcitation.Visible light excitation could further promote the charge transfer between catalytic Pd component and the support Ti N,resulting in electron-rich Pd sites on Cu Pd/Ti N.Moreover,light excitation on Cu Pd/Ti N generates strong chemisorption of iodobenzene and styrene,favoring the activation of reactants for Heck reaction.DFT calculations suggest that electron-rich Cu Pd sites ideally lower the activation energy barrier for the coupling reaction.This work provides valuable insights for mechanistic understanding of plasmonic photocatalysis.展开更多
Large-scale deployment of carbon dioxide(CO_(2))removal technology is an essential step to cope with global warming and achieve carbon neutrality.Direct air capture(DAC)has recently received increasing attention given...Large-scale deployment of carbon dioxide(CO_(2))removal technology is an essential step to cope with global warming and achieve carbon neutrality.Direct air capture(DAC)has recently received increasing attention given the high flexibility to remove CO_(2)from discrete sources.Porous materials with adjustable pore characteristics are promising sorbents with low or no latent heat of vaporization.This review article has summarized the recent development of porous sorbents for DAC,with a focus of pore engineering strategy and adsorption mechanism.Physisorbents such as zeolites,porous carbons,metal-organic frameworks(MOFs),and amine-modified chemisorbents have been discussed and their challenges in practical application have been analyzed.At last,future directions have been proposed,and it is expected to inspire collaborations from chemistry,environment,material science and engineering communities.展开更多
Electrocatalysis has been extensively explored for the storage and conversion of renewable electric power.Understanding the physisorption and chemisorption processes at electrified solid–liquid interfaces(ESLIs)is cr...Electrocatalysis has been extensively explored for the storage and conversion of renewable electric power.Understanding the physisorption and chemisorption processes at electrified solid–liquid interfaces(ESLIs)is crucial for revealing the typical surface restructuring and catalyst dissolution during electrocatalysis.Although advanced in situ tools and theoretical models have been proposed[1,2],identifying the nature of the active sites with atomic-scale spatial resolution remains a challenge,especially at ESLIs.In a recent work published in Nature,Zhang et al.[3]reported a groundbreaking atomic-resolution imaging of the structural dynamics of Cu nanowire catalysts in ESLIs for electrochemical CO_(2)reduction(ECR).展开更多
Carbon capture and storage(CCS)is an advanced environmental technology for mitigating CO_(2) emissions and addressing climate change.Among the various approaches,adsorption has emerged as a promising method for CO_(2)...Carbon capture and storage(CCS)is an advanced environmental technology for mitigating CO_(2) emissions and addressing climate change.Among the various approaches,adsorption has emerged as a promising method for CO_(2) capture due to its effiectiveness and practicality.This review explores the potential of clay minerals as adsorbents for CO_(2) capture,providing an in-depth analysis of their inherent properties and the mechanisms involved in adsorption process.The review begins with an introduction to CCS and the concept of adsorption,followed by a detailed examination of various clay minerals,including sepiolite,montmorillonite,bentonite,kaolinite,saponite,halloysite,and illite.Each mineral’s suitability for CO_(2) adsorption is assessed,highlighting the specific properties that contribute to their performance.The mechanisms of CO_(2) adsorption including physisorption,chemisorption,ion exchange,pore diffusion,intraparticle diffusion,surface complexation,and competitive adsorption are thoroughly discussed.The review also covers the modification of clay minerals through physical and chemical treatments,amine functionalization,and composite formation to enhance their CO_(2) adsorption capacity.Additionally,regeneration methods such as temperature-swing adsorption(TSA),pressure-swing adsorption(PSA),and purging are discussed,along with CO_(2) recovery and storage techniques for improving energy efficiency.The review concludes with an overview of characterization methods for clay-based adsorbents and potential applications,while addressing the challenges and future trends in thefield.This work emphasizes the promising role of clay-based adsorbents in advancing CCS technology.展开更多
Li_(6)ZnO_(4)was chemically modified by nickel addition,in order to develop different compositions of the solid solution Li_(6)Zn_(1-x)Ni_(x)O_(4).These materials were evaluated bifunctionally;analyzing their CO_(2)ca...Li_(6)ZnO_(4)was chemically modified by nickel addition,in order to develop different compositions of the solid solution Li_(6)Zn_(1-x)Ni_(x)O_(4).These materials were evaluated bifunctionally;analyzing their CO_(2)capture performances,aswell as on their catalytic properties for H_(2)production via dry reforming of methane(DRM).The crystal structures of Li_(6)Zn_(1-x)Ni_(x)O_(4)solid solution samples were determined through X-ray diffraction,which confirmed the integration of nickel ions up to a concentration around 20 mol%,meanwhile beyond this value,a secondary phase was detected.These results were supported by XPS and TEM analyses.Then,dynamic and isothermal thermogravimetric analyses of CO_(2)capture revealed that Li_(6)Zn_(1-x)Ni_(x)O_(4)solid solution samples exhibited good CO_(2)chemisorption efficiencies,similarly to the pristine Li_(6)ZnO_(4)chemisorption trends observed.Moreover,a kinetic analysis of CO_(2)isothermal chemisorptions,using the Avrami-Erofeev model,evidenced an increment of the constant rates as a function of the Ni content.Since Ni^(2+)ions incorporation did not reduce the CO_(2)capture efficiency and kinetics,the catalytic properties of thesematerialswere evaluated in the DRM process.Results demonstrated that nickel ions favored hydrogen(H_(2))production over the pristine Li_(6)ZnO_(4)phase,despite a second H2 production reaction was determined,methane decomposition.Thereby,Li_(6)Zn_(1-x)Ni_(x)O_(4)ceramics can be employed as bifunctional materials.展开更多
In this study,six-dimensional(6D)time-dependent wave packet calcula-tions were employed to investigate the dissociation of HCl molecules on two bimetallic surfaces,Cu/Ag(111)and Cu/Au(111).These calculations were base...In this study,six-dimensional(6D)time-dependent wave packet calcula-tions were employed to investigate the dissociation of HCl molecules on two bimetallic surfaces,Cu/Ag(111)and Cu/Au(111).These calculations were based on two accurate potential energy surfaces(PESs)constructed using neu-ral network methodology.Density functional theory(DFT)calculations revealed that the static barrier heights for HCl on Cu/Ag(111)and Cu/Au(111)were 0.32 eV and 0.28 eV,respectively.These values are significantly lower than the barrier height on pure Cu(111)(0.52 eV),primarily due to surface strain effects.However,it was found that the 6D dissociation probability of HCl in(v=0,1,j=0)states on Cu/Au(111)was considerably lower,despite its barrier height being 0.04 eV lower than that for Cu/Ag(111).The underlying mechanism for this observation was attributed to the non-monotonic dependence of the minimum energy path(MEP)on the molecular orientation,which was induced by charge transfer effect for HCl+Cu/Au(111).In contrast,HCl+Cu/Ag(111)exhibited a monotonic dependence.These contrasting behaviors led to dis-tinct differences in rotational alignment and excitation effects for the two reactions.展开更多
Carbon nanofibers films are typical flexible electrode in the field of energy storage,but their application in Zinc-ion hybrid capacitors(ZIHCs)is limited by the low energy density due to the lack of active adsorption...Carbon nanofibers films are typical flexible electrode in the field of energy storage,but their application in Zinc-ion hybrid capacitors(ZIHCs)is limited by the low energy density due to the lack of active adsorption sites.In this work,an in-situ exfoliation strategy is reported to modulate the chemisorption sites of carbon nanofibers by high pyridine/pyrrole nitrogen doping and carbonyl functionalization.The experimental results and theoretical calculations indicate that the highly electronegative pyridine/pyrrole nitrogen dopants can not only greatly reduce the binding energy between carbonyl group and Z n2+by inducing charge delocalization of the carbonyl group,but also promote the adsorption of Zn2+by bonding with the carbonyl group to form N–Zn–O bond.Benefit from the multiple highly active chemisorption sites generated by the synergy between carbonyl groups and pyridine/pyrrole nitrogen atoms,the resulting carbon nanofibers film cathode displays a high energy density,an ultralong-term lifespan,and excellent capacity reservation under commercial mass loading(14.45 mg cm-2).Particularly,the cathodes can also operate stably in flexible or quasi-solid devices,indicating its application potential in flexible electronic products.This work established a universal method to solve the bottleneck problem of insufficient active adsorption sites of carbon-based ZIHCs.Imoproved should be changed into Improved.展开更多
The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and nitrogen, dispersion of metallic Ru. and catalytic activity of active carbon (AC) supported ruthenium catalyst for ammonia synthes...The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and nitrogen, dispersion of metallic Ru. and catalytic activity of active carbon (AC) supported ruthenium catalyst for ammonia synthesis have been studied by means of pulse chromatography, temperature-programmed desorption, and activity test. Promoters K, Ba and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly, and particularly, potassium exhibited the best promotion on the activity because of the strong electronic donation to metallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or triple promoters. The activity of Ru/AC catalyst is dependent on the adsorption of hydrogen and nitrogen. The high activity of catalyst could be ascribed to strong dissociation of nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit the adsorption of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by Sm2O3 shows the best dispersion of metallic Ru, since the partly reduced SmOx on the surface modifies the morphology of active sites and favors the dispersion of metallic Ru. The activity of Ru/AC catalysts is in accordance to the corresponding amount of nitrogen chemisorption and the desorption activation energy of nitrogen. The desorption activation energy for nitrogen decreases in the order of Ru>Ru-Ba>Ru-Sm>Ru-Ba-Sm>Ru-K>Ru-K-Sm>Ru-K-Ba>Ru-K-Ba-Sm, just opposite to the order of catalytic activity, suggesting that the ammonia synthesis over Ru-based catalyst is controlled by the step of dissociation of nitrogen.展开更多
An atomic group model of the disordered binary alloy Rhx-Pt1-x has been constructed to investigate surface segregation. According to the model, we have calculated the electronic structure of the Rhx-Pt1-x alloy surfac...An atomic group model of the disordered binary alloy Rhx-Pt1-x has been constructed to investigate surface segregation. According to the model, we have calculated the electronic structure of the Rhx-Pt1-x alloy surface by using the recursion method when O atoms are adsorbed on the Rhx-Pt1-x （110） surface under the condition of coverage 0.5. The calculation results indicate that the chemical adsorption of O changes greatly the density of states near the Fermi level, and the surface segregation exhibits a reversal behaviour. In addition, when x 〈 0.3, the surface on which O is adsorbed displays the property of Pt; whereas when x 〉 0.3 it displays the property of Rh.展开更多
The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we...The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we develop a facile "in-situ growth" method to decorate ultra-small Mo2 C nanoparticles(USMo2 C) on the surface of Ketjen Black(KB) to functionalize the commercial polypropylene(PP) separators,which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries. Importantly, the US-Mo2 C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels, which can promote electron transport and provide physical barrier and volume expansion space for polysulfides. Due to the combined effects of the US-Mo2 C and KB, Li-S cells employing the multifunctional PP separators modified with KB/US-Mo2 C composite(KB/US-Mo2 C@PP) exhibit a high specific capacity(1212.8 mAh g^(-1) at 0.2 C), and maintain a reversible capacity of 1053.3 m Ah g^(-1) after 100 cycles.More importantly, the KB/US-Mo2 C@PP cells with higher sulfur mass loading of 4.9 mg cm^(-2) have superb areal capacity of 2.3 mAh cm^(-2). This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.展开更多
Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we dem...Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we demonstrate that the surface of two-dimensional Co-based MOF is modified by decorating Ag quantum dots(QDs)simply through in-situ reduction of Ag+ions.Toward oxygen evolution reaction(OER),it reveals that the catalysis is mediated by the reversible redox of Co sites between Co^(3+) and Co^(4+) states coupling with transfer of OHions.The decoration of Ag QDs decreases the redox potential of Co sites,and thus effectively decreases the overpotential of OER.The TOFs of Co sites are increased by 77 times to reach 5.4 s^(-1) at an overpotential of 0.35 V.We attribute the activity enhancement to the tuning of the coupling process between Co sites and OHions during the redox of Co sites by Ag QDs decoration based on Pourbaix analysis.展开更多
We performed density functional theory calculations of O2, CO2, and H2O chemisorption on the UN（001） surface using the generalized gradient approximation and PW91 exchangecorrelation functional at non-spin polarized...We performed density functional theory calculations of O2, CO2, and H2O chemisorption on the UN（001） surface using the generalized gradient approximation and PW91 exchangecorrelation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. molecular distance from UN（001） surface were optimized for four symmetrical chemisorption sites. The results showed that the bridge parallel, hollow parallel and bridge hydrogen-up adsorption sites were the most stable site for O2, CO2, and H2O molecular with chemisorption energies of 14.48, 4.492, and 5.85 kJ/mol, respectively. From the point of adsorbent （the UN（001） surface）, interaction of O2 with the UN（001） surface was of the maximum magnitude, then CO2 and H2O, indicating that these interactions were associated with structures of the adsorbate. O2 chemisorption caused N atoms on the surface to migrate into the bulk, however CO2 and H2O had a moderate and negligible effect on the surface, respectively. Calculated electronic density of states demonstrated the electronic charge transfer between s, p orbital in chemisorption molecular and U6d, U5f orbital.展开更多
The adsorption of CH3O and H on the (100) facet of gold was studied using self-consistent periodic density functional theory (DFT-GGA) calculations. The best binding site, energy, and structural parameter, as well as ...The adsorption of CH3O and H on the (100) facet of gold was studied using self-consistent periodic density functional theory (DFT-GGA) calculations. The best binding site, energy, and structural parameter, as well as the local density of states, of each species were determined. CH3O is predicted to strongly adsorb on the bridge and hollow sites, with the bridge site as preferred one, with one of the hydrogen atoms pointing toward a fourfold vacancy (bridge-H hollow). The top site was found to be unstable, the CH3O radical moving to the bridge –H top site during geometry optimization. Adsorption of H is unstable on the hollow site, the atom moving to the bridge site during geometry optimization. The 4-layer slab is predicted to be endothermic with respect to gaseous H2 and a clean Au surface.展开更多
The dissociative chemisorption of N_(2) is the rate-limiting step for ammonia synthesis in industry.Here,we investigated the role of initially vibrational excitation and ro-tational excitation of N_(2) for its reactiv...The dissociative chemisorption of N_(2) is the rate-limiting step for ammonia synthesis in industry.Here,we investigated the role of initially vibrational excitation and ro-tational excitation of N_(2) for its reactivity on the Fe(111)surface,based on a recently developed six-dimensional potential energy surface.Six-dimensional quantum dynamics study was carried out to investi-gate the effect of vibrational excitation for incidence energy below 1.6 eV,due to sig-nificant quantum effects for this reaction.The effects of vibrational and rotational excitations at high incidence energies were revealed by quasiclassical trajectory calculations.We found that raising the translational energy can enhance the dissociation probability to some extent,however,the vibrational excitation or rotational excitation can promote disso-ciation more efficiently than the same amount of translational energy.This study provides valuable insight into the mode-specific dynamics of this heavy diatom-surface reaction.展开更多
基金supported by Shanghai Pujiang Program(No.21PJ1400400)the Research Start-up Fund at Donghua University+2 种基金the Foundation of State Key Laboratory of Coal Combustion(No.FSKLCCA2309)the National Natural Science Foundation of China(No.22302109)the Australian Research Council(No.DP230102740)。
文摘In this work,we developed plasmonic photocatalyst composed of Cu Pd alloy nanoparticles supported on Ti N,the optimized Cu_(3)Pd_(2)/Ti N catalyst shows excellent conversion(>96%)and selectivity(>99%)for Heck reaction at 50℃ under visible light irradiation.By in-situ spectroscopic investigations,we find that visible light excitation could achieve stable metallic Cu species on the surface of Cu Pd alloy nanoparticles,thereby eliminating the inevitable surface oxides of Cu based catalyst.The in-situ formed metallic Cu species under irradiation take advantage of the strong interactions of Cu with visible light,and manifest in the localized surface plasmon resonances(LSPR)photoexcitation.Visible light excitation could further promote the charge transfer between catalytic Pd component and the support Ti N,resulting in electron-rich Pd sites on Cu Pd/Ti N.Moreover,light excitation on Cu Pd/Ti N generates strong chemisorption of iodobenzene and styrene,favoring the activation of reactants for Heck reaction.DFT calculations suggest that electron-rich Cu Pd sites ideally lower the activation energy barrier for the coupling reaction.This work provides valuable insights for mechanistic understanding of plasmonic photocatalysis.
基金financial support from the National Natural Science Foundation of China(Nos.22278011,22225803,22038001 and 22108007)Beijing Natural Science Foundation(No.Z230023)+1 种基金The Science&Technology Project of Beijing Municipal Education Committee(No.KZ201810005004)Beijing Nova Program(No.Z211100002121094)。
文摘Large-scale deployment of carbon dioxide(CO_(2))removal technology is an essential step to cope with global warming and achieve carbon neutrality.Direct air capture(DAC)has recently received increasing attention given the high flexibility to remove CO_(2)from discrete sources.Porous materials with adjustable pore characteristics are promising sorbents with low or no latent heat of vaporization.This review article has summarized the recent development of porous sorbents for DAC,with a focus of pore engineering strategy and adsorption mechanism.Physisorbents such as zeolites,porous carbons,metal-organic frameworks(MOFs),and amine-modified chemisorbents have been discussed and their challenges in practical application have been analyzed.At last,future directions have been proposed,and it is expected to inspire collaborations from chemistry,environment,material science and engineering communities.
基金financially supported by the Natural Science Foundation of Shandong(ZR2023ME014)。
文摘Electrocatalysis has been extensively explored for the storage and conversion of renewable electric power.Understanding the physisorption and chemisorption processes at electrified solid–liquid interfaces(ESLIs)is crucial for revealing the typical surface restructuring and catalyst dissolution during electrocatalysis.Although advanced in situ tools and theoretical models have been proposed[1,2],identifying the nature of the active sites with atomic-scale spatial resolution remains a challenge,especially at ESLIs.In a recent work published in Nature,Zhang et al.[3]reported a groundbreaking atomic-resolution imaging of the structural dynamics of Cu nanowire catalysts in ESLIs for electrochemical CO_(2)reduction(ECR).
文摘Carbon capture and storage(CCS)is an advanced environmental technology for mitigating CO_(2) emissions and addressing climate change.Among the various approaches,adsorption has emerged as a promising method for CO_(2) capture due to its effiectiveness and practicality.This review explores the potential of clay minerals as adsorbents for CO_(2) capture,providing an in-depth analysis of their inherent properties and the mechanisms involved in adsorption process.The review begins with an introduction to CCS and the concept of adsorption,followed by a detailed examination of various clay minerals,including sepiolite,montmorillonite,bentonite,kaolinite,saponite,halloysite,and illite.Each mineral’s suitability for CO_(2) adsorption is assessed,highlighting the specific properties that contribute to their performance.The mechanisms of CO_(2) adsorption including physisorption,chemisorption,ion exchange,pore diffusion,intraparticle diffusion,surface complexation,and competitive adsorption are thoroughly discussed.The review also covers the modification of clay minerals through physical and chemical treatments,amine functionalization,and composite formation to enhance their CO_(2) adsorption capacity.Additionally,regeneration methods such as temperature-swing adsorption(TSA),pressure-swing adsorption(PSA),and purging are discussed,along with CO_(2) recovery and storage techniques for improving energy efficiency.The review concludes with an overview of characterization methods for clay-based adsorbents and potential applications,while addressing the challenges and future trends in thefield.This work emphasizes the promising role of clay-based adsorbents in advancing CCS technology.
基金This work was carried out in the framework of PAPIIT-UNAM(IN-205823)project.
文摘Li_(6)ZnO_(4)was chemically modified by nickel addition,in order to develop different compositions of the solid solution Li_(6)Zn_(1-x)Ni_(x)O_(4).These materials were evaluated bifunctionally;analyzing their CO_(2)capture performances,aswell as on their catalytic properties for H_(2)production via dry reforming of methane(DRM).The crystal structures of Li_(6)Zn_(1-x)Ni_(x)O_(4)solid solution samples were determined through X-ray diffraction,which confirmed the integration of nickel ions up to a concentration around 20 mol%,meanwhile beyond this value,a secondary phase was detected.These results were supported by XPS and TEM analyses.Then,dynamic and isothermal thermogravimetric analyses of CO_(2)capture revealed that Li_(6)Zn_(1-x)Ni_(x)O_(4)solid solution samples exhibited good CO_(2)chemisorption efficiencies,similarly to the pristine Li_(6)ZnO_(4)chemisorption trends observed.Moreover,a kinetic analysis of CO_(2)isothermal chemisorptions,using the Avrami-Erofeev model,evidenced an increment of the constant rates as a function of the Ni content.Since Ni^(2+)ions incorporation did not reduce the CO_(2)capture efficiency and kinetics,the catalytic properties of thesematerialswere evaluated in the DRM process.Results demonstrated that nickel ions favored hydrogen(H_(2))production over the pristine Li_(6)ZnO_(4)phase,despite a second H2 production reaction was determined,methane decomposition.Thereby,Li_(6)Zn_(1-x)Ni_(x)O_(4)ceramics can be employed as bifunctional materials.
基金supported by the National Key R&D Program of China(No.2018YFE0203003)the National Natural Science Foundation of China(Nos.22173101,22173099,22288201,21703242)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0970203)the Innovation Program for Quantum Science and Technology(No.2021ZD0303305)Dalian Talents Innovation Support Program(No.2021RD05)the Open Fund(SKLMRD-K202508)of the State Key Laboratory of Molecular Reaction Dynamics in Dalian Institute of Chemical Physics,Chinese Academy of Sciences.The computational resources are supported by SongShan Lake HPC Center(SSL-HPC)in Great Bay University.
文摘In this study,six-dimensional(6D)time-dependent wave packet calcula-tions were employed to investigate the dissociation of HCl molecules on two bimetallic surfaces,Cu/Ag(111)and Cu/Au(111).These calculations were based on two accurate potential energy surfaces(PESs)constructed using neu-ral network methodology.Density functional theory(DFT)calculations revealed that the static barrier heights for HCl on Cu/Ag(111)and Cu/Au(111)were 0.32 eV and 0.28 eV,respectively.These values are significantly lower than the barrier height on pure Cu(111)(0.52 eV),primarily due to surface strain effects.However,it was found that the 6D dissociation probability of HCl in(v=0,1,j=0)states on Cu/Au(111)was considerably lower,despite its barrier height being 0.04 eV lower than that for Cu/Ag(111).The underlying mechanism for this observation was attributed to the non-monotonic dependence of the minimum energy path(MEP)on the molecular orientation,which was induced by charge transfer effect for HCl+Cu/Au(111).In contrast,HCl+Cu/Ag(111)exhibited a monotonic dependence.These contrasting behaviors led to dis-tinct differences in rotational alignment and excitation effects for the two reactions.
基金funds from the National Natural Science Foundation of China(51772082,51804106,and 51574117)the Natural Science Foundation of Hunan Province(2019JJ30002,2019JJ50061 and 2020CB1007)Natural Science Foundation of Guangdong Providence(2018A030310571)。
文摘Carbon nanofibers films are typical flexible electrode in the field of energy storage,but their application in Zinc-ion hybrid capacitors(ZIHCs)is limited by the low energy density due to the lack of active adsorption sites.In this work,an in-situ exfoliation strategy is reported to modulate the chemisorption sites of carbon nanofibers by high pyridine/pyrrole nitrogen doping and carbonyl functionalization.The experimental results and theoretical calculations indicate that the highly electronegative pyridine/pyrrole nitrogen dopants can not only greatly reduce the binding energy between carbonyl group and Z n2+by inducing charge delocalization of the carbonyl group,but also promote the adsorption of Zn2+by bonding with the carbonyl group to form N–Zn–O bond.Benefit from the multiple highly active chemisorption sites generated by the synergy between carbonyl groups and pyridine/pyrrole nitrogen atoms,the resulting carbon nanofibers film cathode displays a high energy density,an ultralong-term lifespan,and excellent capacity reservation under commercial mass loading(14.45 mg cm-2).Particularly,the cathodes can also operate stably in flexible or quasi-solid devices,indicating its application potential in flexible electronic products.This work established a universal method to solve the bottleneck problem of insufficient active adsorption sites of carbon-based ZIHCs.Imoproved should be changed into Improved.
基金Supported by the Natural Science Foundation of Zhejiang Province (No. 299015), the Development Plan of Youth Mainstay Teacher of the Education Ministry of China and the Special Foundation for Youth Talent by Zhejiang (RC9702).
文摘The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and nitrogen, dispersion of metallic Ru. and catalytic activity of active carbon (AC) supported ruthenium catalyst for ammonia synthesis have been studied by means of pulse chromatography, temperature-programmed desorption, and activity test. Promoters K, Ba and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly, and particularly, potassium exhibited the best promotion on the activity because of the strong electronic donation to metallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or triple promoters. The activity of Ru/AC catalyst is dependent on the adsorption of hydrogen and nitrogen. The high activity of catalyst could be ascribed to strong dissociation of nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit the adsorption of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by Sm2O3 shows the best dispersion of metallic Ru, since the partly reduced SmOx on the surface modifies the morphology of active sites and favors the dispersion of metallic Ru. The activity of Ru/AC catalysts is in accordance to the corresponding amount of nitrogen chemisorption and the desorption activation energy of nitrogen. The desorption activation energy for nitrogen decreases in the order of Ru>Ru-Ba>Ru-Sm>Ru-Ba-Sm>Ru-K>Ru-K-Sm>Ru-K-Ba>Ru-K-Ba-Sm, just opposite to the order of catalytic activity, suggesting that the ammonia synthesis over Ru-based catalyst is controlled by the step of dissociation of nitrogen.
基金Project supported by the National Natural Science Foundation of China （Grant No 50571071）.
文摘An atomic group model of the disordered binary alloy Rhx-Pt1-x has been constructed to investigate surface segregation. According to the model, we have calculated the electronic structure of the Rhx-Pt1-x alloy surface by using the recursion method when O atoms are adsorbed on the Rhx-Pt1-x （110） surface under the condition of coverage 0.5. The calculation results indicate that the chemical adsorption of O changes greatly the density of states near the Fermi level, and the surface segregation exhibits a reversal behaviour. In addition, when x 〈 0.3, the surface on which O is adsorbed displays the property of Pt; whereas when x 〉 0.3 it displays the property of Rh.
基金financially supported by the National Natural Science Foundation of China for Innovative Research Groups (No. 51621002)the National Key Research and Development Program of China (Grant No. 2016YFA0203700)+5 种基金NSFC (Grant No 51672083)Program of Shanghai Academic/Technology Research Leader (18XD1401400)Basic Research Program of Shanghai (17JC1404702)Leading talents in Shanghai in 2018The Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, the 111 project (B14018)The Fundamental Research Funds for Central Universities (222201718002)。
文摘The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur(Li-S) batteries.Herein, we develop a facile "in-situ growth" method to decorate ultra-small Mo2 C nanoparticles(USMo2 C) on the surface of Ketjen Black(KB) to functionalize the commercial polypropylene(PP) separators,which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries. Importantly, the US-Mo2 C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels, which can promote electron transport and provide physical barrier and volume expansion space for polysulfides. Due to the combined effects of the US-Mo2 C and KB, Li-S cells employing the multifunctional PP separators modified with KB/US-Mo2 C composite(KB/US-Mo2 C@PP) exhibit a high specific capacity(1212.8 mAh g^(-1) at 0.2 C), and maintain a reversible capacity of 1053.3 m Ah g^(-1) after 100 cycles.More importantly, the KB/US-Mo2 C@PP cells with higher sulfur mass loading of 4.9 mg cm^(-2) have superb areal capacity of 2.3 mAh cm^(-2). This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.
基金gratefully acknowledge the financial support from the National Natural Science Foundation of China(51802265,22002119)the Fundamental Research Funds for the Central Universities of China+2 种基金the Initiative Postdocs Supporting Program(BX20190281)the General Program,Science and Technology Program of Taicang,China(TC2020JC01)the National Natural Science Foundation of Jiangsu,China(BK20200261)。
文摘Interfacial engineering to alter the configuration of active sites in heterogeneous catalysts is a potential strategy for activity enhancement,but it remains unelucidated for metal-organic frameworks(MOFs).Here,we demonstrate that the surface of two-dimensional Co-based MOF is modified by decorating Ag quantum dots(QDs)simply through in-situ reduction of Ag+ions.Toward oxygen evolution reaction(OER),it reveals that the catalysis is mediated by the reversible redox of Co sites between Co^(3+) and Co^(4+) states coupling with transfer of OHions.The decoration of Ag QDs decreases the redox potential of Co sites,and thus effectively decreases the overpotential of OER.The TOFs of Co sites are increased by 77 times to reach 5.4 s^(-1) at an overpotential of 0.35 V.We attribute the activity enhancement to the tuning of the coupling process between Co sites and OHions during the redox of Co sites by Ag QDs decoration based on Pourbaix analysis.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.51271198） and Self- Topics Fund of Xi＇an Research Institute of High Technology （No.YX2012cxpy06）. Ru-song Li would like to thank Wen Li from Xi＇an Research Institute of Hi-Tech for useful discussions and studentship support.
文摘We performed density functional theory calculations of O2, CO2, and H2O chemisorption on the UN（001） surface using the generalized gradient approximation and PW91 exchangecorrelation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. molecular distance from UN（001） surface were optimized for four symmetrical chemisorption sites. The results showed that the bridge parallel, hollow parallel and bridge hydrogen-up adsorption sites were the most stable site for O2, CO2, and H2O molecular with chemisorption energies of 14.48, 4.492, and 5.85 kJ/mol, respectively. From the point of adsorbent （the UN（001） surface）, interaction of O2 with the UN（001） surface was of the maximum magnitude, then CO2 and H2O, indicating that these interactions were associated with structures of the adsorbate. O2 chemisorption caused N atoms on the surface to migrate into the bulk, however CO2 and H2O had a moderate and negligible effect on the surface, respectively. Calculated electronic density of states demonstrated the electronic charge transfer between s, p orbital in chemisorption molecular and U6d, U5f orbital.
文摘The adsorption of CH3O and H on the (100) facet of gold was studied using self-consistent periodic density functional theory (DFT-GGA) calculations. The best binding site, energy, and structural parameter, as well as the local density of states, of each species were determined. CH3O is predicted to strongly adsorb on the bridge and hollow sites, with the bridge site as preferred one, with one of the hydrogen atoms pointing toward a fourfold vacancy (bridge-H hollow). The top site was found to be unstable, the CH3O radical moving to the bridge –H top site during geometry optimization. Adsorption of H is unstable on the hollow site, the atom moving to the bridge site during geometry optimization. The 4-layer slab is predicted to be endothermic with respect to gaseous H2 and a clean Au surface.
基金supported by the National Key R&D Program of China(No.2018YFE0203003)the National Natural Science Foundation of China(No.22173099 and No.22173101)the Liaoning Revitalization Talents Program(No.XLYC1907190)。
文摘The dissociative chemisorption of N_(2) is the rate-limiting step for ammonia synthesis in industry.Here,we investigated the role of initially vibrational excitation and ro-tational excitation of N_(2) for its reactivity on the Fe(111)surface,based on a recently developed six-dimensional potential energy surface.Six-dimensional quantum dynamics study was carried out to investi-gate the effect of vibrational excitation for incidence energy below 1.6 eV,due to sig-nificant quantum effects for this reaction.The effects of vibrational and rotational excitations at high incidence energies were revealed by quasiclassical trajectory calculations.We found that raising the translational energy can enhance the dissociation probability to some extent,however,the vibrational excitation or rotational excitation can promote disso-ciation more efficiently than the same amount of translational energy.This study provides valuable insight into the mode-specific dynamics of this heavy diatom-surface reaction.
