Single-atom catalysts(SACs)have become an emerging frontier trend in the field of heterogeneous catalysis due to their high activity,selectivity and stability.SACs could greatly increase the availabilities of the acti...Single-atom catalysts(SACs)have become an emerging frontier trend in the field of heterogeneous catalysis due to their high activity,selectivity and stability.SACs could greatly increase the availabilities of the active metal atoms in many catalytic reactions by reducing the size to single atom scale.Graphene-supported metal SACs have also drawn considerable attention due to the unique lattice structure and physicochemical properties of graphene,resulting in superior activity and selectivity for several chemical reactions.In this paper,we review recent progress in the fabrications,advanced characterization tools and advantages of graphene-supported metal SACs,focusing on their applications in catalytic reactions such as CO oxidation,the oxidation of benzene to phenol,hydrogen evolution reaction,methanol oxidation reaction,oxygen reduction reaction,hydrogenation and photoelectrocatalysis.We also propose the development of SACs towards industrialization in the future.展开更多
An FeOx‐based Pt single‐atom catalyst(SAC),Pt1/FeOx,has stimulated significant recent interest owing to its extraordinary activity toward CO oxidation.The concept of SAC has also been successfully extended to other ...An FeOx‐based Pt single‐atom catalyst(SAC),Pt1/FeOx,has stimulated significant recent interest owing to its extraordinary activity toward CO oxidation.The concept of SAC has also been successfully extended to other FeOx supported transition metal systems both experimentally and theoretically.However,the FeOx substrate itself(denoted by Fe1/FeOx following the same nomenclature of Pt1/FeOx)as a typical transition metal oxide possesses a very low catalytic activity toward CO oxidation,although it can be viewed as Fe1/FeOx SAC.Here,to understand the catalytic mechanism of FeOx‐based SACs for CO oxidation,we have performed density functional theory calculations on Pt1/FeOx and Fe1/FeOx for CO oxidation to address the differences between these two SACs in terms of the catalytic mechanism of CO oxidation and the chemical behavior of the catalysts.Our calculation results indicated that the catalytic cycle of Fe1/FeOx is much more difficult to accomplish than that of SAC Pt1/FeOx because of a high activation barrier(1.09eV)for regeneration of the oxygen vacancy formed when the second CO2molecule desorbs from the surface.Moreover,density of states and Bader charge analysis revealed differences in the catalytic performance for CO oxidation by the SACs Fe1/FeOx and Pt1/FeOx.This work provides insights into the fundamental interactions between the single‐atom Pt1and FeOx substrate,and the exceptional catalytic performance of this system for CO oxidation.展开更多
Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures....Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures.However,the role of SACs supports on the catalytic performance does not receive enough research attentions.Here,we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions(ZnN/CNO).ZnN/CNO catalysts show an excellent high selectivity for CO_(2) electro-reduction to CO with a Faradaic efficiency of CO(FECO)up to 97%at -0.47 V(vs.reversible hydrogen electrode,RHE)and remarkable durability without activity decay.To our knowledge,ZnN/CNO is the best activity for the Zn based catalysts up to now,and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate,although the graphene with larger surface area.The exact role of such carbon nano-onions(CNO)support is studied systematically by coupling characterizations and electrochemistry with density functional theory(DFT)calculations,which have attributed such good performance to the increased curvature.Such increased curvature modifies the surface charge,which then changes the adsorption energies of key intermediates,and improves the selectivity for CO generation accordingly.展开更多
The nitrogen reduction reaction(NRR)under ambient conditions is still challenging due to the inertness of N2.Herein,we report a series of superior NRR catalysts identified by examining Ti2NO2 MXenes embedded with 28 d...The nitrogen reduction reaction(NRR)under ambient conditions is still challenging due to the inertness of N2.Herein,we report a series of superior NRR catalysts identified by examining Ti2NO2 MXenes embedded with 28 different single-atom catalysts using first-principles calculations.The stability of this system was first verified using formation energies,and it is discovered that N2 can be effectively adsorbed due to the synergistic effect between single atom catalysis and the Ti atoms.Examination of the electronic structure demonstrated that this design satisfies orbital symmetry matching where“acceptor-donor”interaction scenario can be realized.A new“enzymatic-distal”reaction mechanism that is a mixture of the enzymatic and distal pathways was also discovered.Among all of the candidates,Ni anchored on MXene system achieves an onset potential as low as–0.13 V,which to the best of our knowledge is the lowest onset potential value reported to date.This work elucidates the significance of orbital symmetry matching and provides theoretical guidance for future studies.展开更多
Unraveling the substrate adsorption structure–performance relationship is pivotal for heterogeneous carbon supported metal single-atom catalysts(M_(1)/C SACs).However,due to the complexity of the functional groups on...Unraveling the substrate adsorption structure–performance relationship is pivotal for heterogeneous carbon supported metal single-atom catalysts(M_(1)/C SACs).However,due to the complexity of the functional groups on carbon material surface,it is still a great challenge.Herein,inspired by structure of enzymes,we used activated carbon(AC),which has adjustable surface oxygen functional groups(OFGs),supported atomically dispersed Fe-N_(4) sites as heme-like catalyst.And based on a combination of scanning transmission electron microscopy(STEM),X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),Mössbauer spectroscopy,Fourier transform infrared(FT-IR)characterizations,kinetics experiments and density functional theory(DFT)calculations,we revealed the effect of substrate adsorption behavior on AC support surface,that is,with the increase of carboxyl group in OFGs,the adsorbed 3,3',5,5'-tetramethylbenzidine(TMB)molecular increased,and consequently the substrate enriched on AC surface.Such carboxyl group as well as Fe-N_(4) active sites synergistically realized high-efficiency peroxidase-like activity,just like the heme.This work suggests that simultaneously constructing metal single-atom active sites and specific functional groups on carbon support surface may open an avenue for engineering metal-support synergistic catalysis in M_(1)/C SACs,which can further improve catalytic performance.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(51502166 and 51881220658)the Scientific Research Program Funded by Shaanxi Provincial Department(17JK0130).
文摘Single-atom catalysts(SACs)have become an emerging frontier trend in the field of heterogeneous catalysis due to their high activity,selectivity and stability.SACs could greatly increase the availabilities of the active metal atoms in many catalytic reactions by reducing the size to single atom scale.Graphene-supported metal SACs have also drawn considerable attention due to the unique lattice structure and physicochemical properties of graphene,resulting in superior activity and selectivity for several chemical reactions.In this paper,we review recent progress in the fabrications,advanced characterization tools and advantages of graphene-supported metal SACs,focusing on their applications in catalytic reactions such as CO oxidation,the oxidation of benzene to phenol,hydrogen evolution reaction,methanol oxidation reaction,oxygen reduction reaction,hydrogenation and photoelectrocatalysis.We also propose the development of SACs towards industrialization in the future.
基金supported by the National Natural Science Foundation of China(21503046,21373206,21203182)the National Basic Research Program of China(2013CB834603)+3 种基金the Natural Science Foundation of Guizhou Province of China(QKJ(2015)2122)Natural Science foundation of Department of Education of Guizhou Province(QJTD(2015)55 and ZDXK(2014)18)the GZEU startup packagethe Open Fund of Shaanxi Key Laboratory of Catalysis to JXL(SXKLC-2017-01)~~
文摘An FeOx‐based Pt single‐atom catalyst(SAC),Pt1/FeOx,has stimulated significant recent interest owing to its extraordinary activity toward CO oxidation.The concept of SAC has also been successfully extended to other FeOx supported transition metal systems both experimentally and theoretically.However,the FeOx substrate itself(denoted by Fe1/FeOx following the same nomenclature of Pt1/FeOx)as a typical transition metal oxide possesses a very low catalytic activity toward CO oxidation,although it can be viewed as Fe1/FeOx SAC.Here,to understand the catalytic mechanism of FeOx‐based SACs for CO oxidation,we have performed density functional theory calculations on Pt1/FeOx and Fe1/FeOx for CO oxidation to address the differences between these two SACs in terms of the catalytic mechanism of CO oxidation and the chemical behavior of the catalysts.Our calculation results indicated that the catalytic cycle of Fe1/FeOx is much more difficult to accomplish than that of SAC Pt1/FeOx because of a high activation barrier(1.09eV)for regeneration of the oxygen vacancy formed when the second CO2molecule desorbs from the surface.Moreover,density of states and Bader charge analysis revealed differences in the catalytic performance for CO oxidation by the SACs Fe1/FeOx and Pt1/FeOx.This work provides insights into the fundamental interactions between the single‐atom Pt1and FeOx substrate,and the exceptional catalytic performance of this system for CO oxidation.
基金This work was supported by the National Key R&D Program of China(2020YFA0710404)the Beijing Natural Science Foundation(2182077)the National Natural Science Foundation of China(21477136,51972281,and 21703250).
文摘Single-atom catalysts(SACs)have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions,thanks to their maximum atom economy,unique electronic and geometric structures.However,the role of SACs supports on the catalytic performance does not receive enough research attentions.Here,we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions(ZnN/CNO).ZnN/CNO catalysts show an excellent high selectivity for CO_(2) electro-reduction to CO with a Faradaic efficiency of CO(FECO)up to 97%at -0.47 V(vs.reversible hydrogen electrode,RHE)and remarkable durability without activity decay.To our knowledge,ZnN/CNO is the best activity for the Zn based catalysts up to now,and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate,although the graphene with larger surface area.The exact role of such carbon nano-onions(CNO)support is studied systematically by coupling characterizations and electrochemistry with density functional theory(DFT)calculations,which have attributed such good performance to the increased curvature.Such increased curvature modifies the surface charge,which then changes the adsorption energies of key intermediates,and improves the selectivity for CO generation accordingly.
文摘The nitrogen reduction reaction(NRR)under ambient conditions is still challenging due to the inertness of N2.Herein,we report a series of superior NRR catalysts identified by examining Ti2NO2 MXenes embedded with 28 different single-atom catalysts using first-principles calculations.The stability of this system was first verified using formation energies,and it is discovered that N2 can be effectively adsorbed due to the synergistic effect between single atom catalysis and the Ti atoms.Examination of the electronic structure demonstrated that this design satisfies orbital symmetry matching where“acceptor-donor”interaction scenario can be realized.A new“enzymatic-distal”reaction mechanism that is a mixture of the enzymatic and distal pathways was also discovered.Among all of the candidates,Ni anchored on MXene system achieves an onset potential as low as–0.13 V,which to the best of our knowledge is the lowest onset potential value reported to date.This work elucidates the significance of orbital symmetry matching and provides theoretical guidance for future studies.
基金The authors wish to acknowledge the support of National Natural Science Foundation of China(NSFC,Nos.21802094,22002118,22172119,and 22102167)Postdoctoral Research Foundation of China(Nos.2020TQ0245 and 2021M693060)Natural Science Basic Research Plan in Shaanxi Province of China(No.2021JM047).
文摘Unraveling the substrate adsorption structure–performance relationship is pivotal for heterogeneous carbon supported metal single-atom catalysts(M_(1)/C SACs).However,due to the complexity of the functional groups on carbon material surface,it is still a great challenge.Herein,inspired by structure of enzymes,we used activated carbon(AC),which has adjustable surface oxygen functional groups(OFGs),supported atomically dispersed Fe-N_(4) sites as heme-like catalyst.And based on a combination of scanning transmission electron microscopy(STEM),X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),Mössbauer spectroscopy,Fourier transform infrared(FT-IR)characterizations,kinetics experiments and density functional theory(DFT)calculations,we revealed the effect of substrate adsorption behavior on AC support surface,that is,with the increase of carboxyl group in OFGs,the adsorbed 3,3',5,5'-tetramethylbenzidine(TMB)molecular increased,and consequently the substrate enriched on AC surface.Such carboxyl group as well as Fe-N_(4) active sites synergistically realized high-efficiency peroxidase-like activity,just like the heme.This work suggests that simultaneously constructing metal single-atom active sites and specific functional groups on carbon support surface may open an avenue for engineering metal-support synergistic catalysis in M_(1)/C SACs,which can further improve catalytic performance.
