Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly im...Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly improve their catalytic activity,it often involves in-plane modulation and requires high temperatures.Herein,we report a novel strategy to manipulate the local electronic structure of SACs via the modulation of axial Co-S bond anchored onto graphitic carbon nitride(C_(3)N_(4))at room temperature(RT).Each Co atom is bonded to four N atoms and one S atom(Co-(N,S)/C_(3)N_(4)).Owing to the greater electronegativity of S in the Co-S bond,the local electronic structure of the Co atoms is available to be controlled at a relatively moderate level.Consequently,when employed for the photocatalytic hydrogen evolution reaction,the adsorption energy of intermediate hydrogen(H*)on the Co atoms is remarkably low.In the presence of the Co-(N,S)/C_(3)N_(4)SACs,the hydrogen evolution rates reach up to 10 mmol/(g·h),which is nearly 10 and 2.5 times greater than the rates in the presence of previously reported transition metal/C_(3)N_(4)and noble platinum nanoparticles(PtNPs)/C_(3)N_(4)catalysts,respectively.Attributed to the tailorable axial Co-S bond in the SAC,the local electronic structure of the Co atoms can be further optimized for other photocatalytic reactions.This axial coordination engineering strategy is universal in catalyst designing and can be used for a variety of photocatalytic applications.展开更多
Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level ...Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.展开更多
Single-atom catalysts(SACs),with the utmost atom utilization,have attracted extensive interests for various catalytic applications.The coordination environment of SACs has been recognized to play a vital role in catal...Single-atom catalysts(SACs),with the utmost atom utilization,have attracted extensive interests for various catalytic applications.The coordination environment of SACs has been recognized to play a vital role in catalysis while their precise regulation at atomic level remains an immense challenge.Herein,a post metal halide modification(PMHM)strategy has been developed to construct Ni-N4 sites with axially coordinated halogen atoms,named Ni1-N-C(X)(X=CI,Br,and I),on pre-synthetic nitrogen-doped carbon derived from metal-organic frameworks.The axial halogen atoms with distinct electronegativity can break the symmetric charge distribution of planar Ni-N4 sites and regulate the electronic states of central Ni atoms in Ni1-N-C(X)(X=Cl,Br,and I).Significantly,the Ni1-N-C(CI)catalyst,decorated with the most electronegative Cl atoms,exhibits Faradaic efficiency of CO up to 94.7%in electrocatalytic CO_(2) reduction,outperforming Ni1-N-C(Br)and Ni1-N-C(I)catalysts.Moreover,Ni1-N-C(CI)also presents superb performance in Zn-CO_(2) battery with ultrahigh CO selectivity and great durability.Theoretical calculations reveal that the axially coordinated Cl atom remarkably facilitates*COOH intermediate formation on single-atom Ni sites,thereby boosting the CO_(2) reduction performance of Ni1-N-C(CI).This work offers a facile strategy to tailor the axial coordination environments of SACs at atomic level and manifests the crucial role of axial coordination microenvironments in catalysis.展开更多
Single-atom catalysts(SACs)have garnered increasingly growing attention in renewable energy scenarios,especially in electrocatalysis due to their unique high efficiency of atom utilization and flexible electronic stru...Single-atom catalysts(SACs)have garnered increasingly growing attention in renewable energy scenarios,especially in electrocatalysis due to their unique high efficiency of atom utilization and flexible electronic structure adjustability.The intensive efforts towards the rational design and synthesis of SACs with versatile local configurations have significantly accelerated the development of efficient and sustainable electrocatalysts for a wide range of electrochemical applications.As an emergent coordination avenue,intentionally breaking the planar symmetry of SACs by adding ligands in the axial direction of metal single atoms offers a novel approach for the tuning of both geometric and electronic structures,thereby enhancing electrocatalytic performance at active sites.In this review,we briefly outline the burgeoning research topic of axially coordinated SACs and provide a comprehensive summary of the recent advances in their synthetic strategies and electrocatalytic applications.Besides,the challenges and outlooks in this research field have also been emphasized.The present review provides an in-depth and comprehensive understanding of the axial coordination design of SACs,which could bring new perspectives and solutions for fine regulation of the electronic structures of SACs catering to high-performing energy electrocatalysis.展开更多
Regulating the coordination environment of transition-metal based materials in the axial direction with heteroatoms has shown great potential in boosting the oxygen reduction reaction(ORR).The coordination configurati...Regulating the coordination environment of transition-metal based materials in the axial direction with heteroatoms has shown great potential in boosting the oxygen reduction reaction(ORR).The coordination configuration and the regulation method are pivotal and elusive.Here,we report a combined strategy of matrix-activization and controlled-induction to modify the CoN_(4)site by axial coordination of Co-S(Co1N_(4)-S_(1)),which was validated by the aberration-corrected electron microscopy and X-ray absorption fine structure analysis.The optimal Co1N_(4)-S_(1)exhibits an excellent alkaline ORR activity,according to the half-wave potential(0.897 V vs.reversible hydrogen electrode(RHE)),Tafel slope(24.67 mV/dec),and kinetic current density.Moreover,the Co1N_(4)-S_(1)based Zn-air battery displays a high power density of 187.55 mW/cm^(2)and an outstanding charge-discharge cycling stability for 160 h,demonstrating the promising application potential.Theoretical calculations indicate that the better regulation of CoN_(4)on electronic structure and thus the highly efficient ORR performance can be achieved by axial Co-S.展开更多
Designing single-atom catalysts for oxygen reduction reaction(ORR)are fashionable but challenging to boost the zinc-air battery performance.Significantly enhanced ORR activity by manganese(Mn)singleatom catalysts can ...Designing single-atom catalysts for oxygen reduction reaction(ORR)are fashionable but challenging to boost the zinc-air battery performance.Significantly enhanced ORR activity by manganese(Mn)singleatom catalysts can be achieved by accurately regulating the coordination number of isolated Mn atoms.Theoretical calculations indicate that the single Mn-N5sites possess lower free energy barrier and higher oxygen adsorption performance than single Mn-N4sites to accelerate the ORR kinetics.Target to it,here we synthesize an atomically dispersed Mn-N5catalyst by precisely axial coordination of pyridinic-N doped into two-dimensional(2D)porous nanocarbon sheets(~3.56 nm thickness),which reveals outstanding catalytic activity and ultrahigh stability for the ORR in zinc-air battery owing to the inhomogeneous charge distribution of Mn-N5sites compared to the conventional single-site Mn-N4catalyst and Pt/C.This work gives a new strategy for in situ regulating the electronic structure of metal single-atoms and further promoting the overall ORR performance in energy systems.展开更多
Metal porphyrins are star molecules that possess welldefined coordination metal centers for versatile catalytic reactions.However,most previous work has focused on the correlations between in-plane symmetric configura...Metal porphyrins are star molecules that possess welldefined coordination metal centers for versatile catalytic reactions.However,most previous work has focused on the correlations between in-plane symmetric configuration of metal-N_(4)sites and their catalytic performance.Addressing the catalytic contribution of additional axial coordination to such symmetric configuration remains a challenge.Theoretical calculations revealed that axially anchoring an extra pyridine on the tetra-coordinated cobalt porphyrin(Co-N4)to construct penta-coordinated cobalt porphyrin(Co-N_(5))renders cobalt a higher electron density,thereby favoring the rate-determining O_(2)adsorption/activation and reducing the oxygen electroreduction barrier.Therefore,a well-defined Co-N_(5)site is rationally introduced into the azo-linked polymer framework for a fundamental structure-catalytic performance correlation study.As-prepared Co-N_(5)catalyst exhibits a 26 mV positive shift in half-wave potential compared with the pyridine-free Co-N_(4)counterpart,discloses a markedly higher power density(141.4 mW cm^(−2)),and possesses better long-term durability(over 160 h cycles)in a Zn-air battery.Moreover,such a Co-N_(5)catalyst also showcases potential applications for CO_(2)reduction with high CO_(2)-to-CO conversion faradic efficiency and better selectivity than the Co-N_(4)counterpart because coordination of the fifth pyridine evokes electronic localization that suppresses a competitive side reaction.This work proves the positive electrocatalytic contribution of axial penta-coordination on well-defined metalporphyrin-based catalysts and offers atomic understanding of the structure-performance correlation on single atom catalysts for future catalyst design.展开更多
The axial coordination effect of F- on the redox behavior of (TPP)Co was investigated by F- titration with cyclic voltammetry detection and spectroeletrochemistry in dichloroethane .It was verified that mono(F-) axial...The axial coordination effect of F- on the redox behavior of (TPP)Co was investigated by F- titration with cyclic voltammetry detection and spectroeletrochemistry in dichloroethane .It was verified that mono(F-) axial adduct (TPP)Co(N ) (F- ) could be reduced at O. 1 V(SCE), and bis(F-) axial adduct (TPP)Co(Ⅲ ) (F-)2 formed with added Fmolar ratio>1 could be reduced at the potential <-0. 6 V(SCE). The equilibrium between (TPP)Co(Ⅲ) (F- ) and (TPP)Co (Ⅲ ) (F- )2 was demonstrated.展开更多
The electrocatalysts containing cobalt-pyrrolic nitrogen-carbon(Co-N_(4)-C)moiety for CO_(2)reduction reaction(CO_(2)RR)have caught much attention.However;the effects of Co valence state and its synergy with gra-phene...The electrocatalysts containing cobalt-pyrrolic nitrogen-carbon(Co-N_(4)-C)moiety for CO_(2)reduction reaction(CO_(2)RR)have caught much attention.However;the effects of Co valence state and its synergy with gra-phene substrate are not clear yet.In this work;cobalt porphyrin(CoTPP)molecule with the intrinsic Co-N_(4)-C moiety is successfully combined with graphene oxide(GO)via three kinds of liquid-phase methods.The ratio of CoTPP to GO and the valence state of Co atom are studied to explore their catalysis for CO_(2)RR to CO.It is found that axial-ly-coordinated Co(III)TPPCl/GO nanocomposites synthesized via a chemical method exhibit better ability for CO_(2)RR;as compared with Co(II)TPP+GO and/or Co(III)TPPCl+GO nanocomposites obtained via a physically mixing way.After optimizing the ratio of CoTPP to GO;the Faradaic efficiency(FE)is more than 90%for CO_(2)RR to CO between−0.7 and−0.8 V vs.reversible hydrogen electrode(RHE)in Co(III)TPPCl/GO75.The synergy be-tween CoTPP and GO and the effect of Co valence state are systematically investigated;indicating that their strong interaction plays the key role in electrocatalytic CO_(2)RR.展开更多
基金National Natural Science Foundation of China(No.22008251)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515010318)Shenzhen Science and Technology Program(No.JCYJ20220531095813031).
文摘Improving the catalytic activity of non-noble metal single atom catalysts(SACs)has attracted considerable attention in materials science.Although optimizing the local electronic structure of single atom can greatly improve their catalytic activity,it often involves in-plane modulation and requires high temperatures.Herein,we report a novel strategy to manipulate the local electronic structure of SACs via the modulation of axial Co-S bond anchored onto graphitic carbon nitride(C_(3)N_(4))at room temperature(RT).Each Co atom is bonded to four N atoms and one S atom(Co-(N,S)/C_(3)N_(4)).Owing to the greater electronegativity of S in the Co-S bond,the local electronic structure of the Co atoms is available to be controlled at a relatively moderate level.Consequently,when employed for the photocatalytic hydrogen evolution reaction,the adsorption energy of intermediate hydrogen(H*)on the Co atoms is remarkably low.In the presence of the Co-(N,S)/C_(3)N_(4)SACs,the hydrogen evolution rates reach up to 10 mmol/(g·h),which is nearly 10 and 2.5 times greater than the rates in the presence of previously reported transition metal/C_(3)N_(4)and noble platinum nanoparticles(PtNPs)/C_(3)N_(4)catalysts,respectively.Attributed to the tailorable axial Co-S bond in the SAC,the local electronic structure of the Co atoms can be further optimized for other photocatalytic reactions.This axial coordination engineering strategy is universal in catalyst designing and can be used for a variety of photocatalytic applications.
基金supported by the National Natural Science Foundation of China(Grant No.52372283)China Postdoctoral Science Foundation(Grant No.2023M730826)+1 种基金Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23121)Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233425).
文摘Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.
基金supported by the National Key Research and Development Program of China(No.2021YFA1500402)the National Natural Science Foundation of China(NSFC)(Nos.21725101,21871244,and 22001242)+3 种基金International Partnership Program of Chinese Academy of Sciences(CAS)(No.211134KYSB20190109)Collaborative Innovation Program of Hefei Science Center,CAS(No.2020HSC-CIP005)the Fundamental Research Funds for the Central Universities(Nos.WK2060000038 and WK2060000040)We thank the XAFS measurements from 1W1B station at BSRF.
文摘Single-atom catalysts(SACs),with the utmost atom utilization,have attracted extensive interests for various catalytic applications.The coordination environment of SACs has been recognized to play a vital role in catalysis while their precise regulation at atomic level remains an immense challenge.Herein,a post metal halide modification(PMHM)strategy has been developed to construct Ni-N4 sites with axially coordinated halogen atoms,named Ni1-N-C(X)(X=CI,Br,and I),on pre-synthetic nitrogen-doped carbon derived from metal-organic frameworks.The axial halogen atoms with distinct electronegativity can break the symmetric charge distribution of planar Ni-N4 sites and regulate the electronic states of central Ni atoms in Ni1-N-C(X)(X=Cl,Br,and I).Significantly,the Ni1-N-C(CI)catalyst,decorated with the most electronegative Cl atoms,exhibits Faradaic efficiency of CO up to 94.7%in electrocatalytic CO_(2) reduction,outperforming Ni1-N-C(Br)and Ni1-N-C(I)catalysts.Moreover,Ni1-N-C(CI)also presents superb performance in Zn-CO_(2) battery with ultrahigh CO selectivity and great durability.Theoretical calculations reveal that the axially coordinated Cl atom remarkably facilitates*COOH intermediate formation on single-atom Ni sites,thereby boosting the CO_(2) reduction performance of Ni1-N-C(CI).This work offers a facile strategy to tailor the axial coordination environments of SACs at atomic level and manifests the crucial role of axial coordination microenvironments in catalysis.
基金The authors acknowledge financial support from the National Key R&D Program of China(2022YFA1505700)National Natural Science Foundation of China(22205232,51971157 and 21601187)Shenzhen Science and Technology Program(JCYJ20210324115412035 and ZDSYS20210813095534001).
文摘Single-atom catalysts(SACs)have garnered increasingly growing attention in renewable energy scenarios,especially in electrocatalysis due to their unique high efficiency of atom utilization and flexible electronic structure adjustability.The intensive efforts towards the rational design and synthesis of SACs with versatile local configurations have significantly accelerated the development of efficient and sustainable electrocatalysts for a wide range of electrochemical applications.As an emergent coordination avenue,intentionally breaking the planar symmetry of SACs by adding ligands in the axial direction of metal single atoms offers a novel approach for the tuning of both geometric and electronic structures,thereby enhancing electrocatalytic performance at active sites.In this review,we briefly outline the burgeoning research topic of axially coordinated SACs and provide a comprehensive summary of the recent advances in their synthetic strategies and electrocatalytic applications.Besides,the challenges and outlooks in this research field have also been emphasized.The present review provides an in-depth and comprehensive understanding of the axial coordination design of SACs,which could bring new perspectives and solutions for fine regulation of the electronic structures of SACs catering to high-performing energy electrocatalysis.
基金supported by the National Key Research and Development Program of China(No.2021YFF0500503)theNational Natural Science Foundation of China(Nos.22275109,21971135,21925202,21872076,and 21471102)+2 种基金the Beijing Municipal Natural Science Foundation(No.2214060)the China Postdoctoral Science Foundation(No.2020M680508)Shenzhen Basic Research Foundation(No.JCYJ20190808110613626).
文摘Regulating the coordination environment of transition-metal based materials in the axial direction with heteroatoms has shown great potential in boosting the oxygen reduction reaction(ORR).The coordination configuration and the regulation method are pivotal and elusive.Here,we report a combined strategy of matrix-activization and controlled-induction to modify the CoN_(4)site by axial coordination of Co-S(Co1N_(4)-S_(1)),which was validated by the aberration-corrected electron microscopy and X-ray absorption fine structure analysis.The optimal Co1N_(4)-S_(1)exhibits an excellent alkaline ORR activity,according to the half-wave potential(0.897 V vs.reversible hydrogen electrode(RHE)),Tafel slope(24.67 mV/dec),and kinetic current density.Moreover,the Co1N_(4)-S_(1)based Zn-air battery displays a high power density of 187.55 mW/cm^(2)and an outstanding charge-discharge cycling stability for 160 h,demonstrating the promising application potential.Theoretical calculations indicate that the better regulation of CoN_(4)on electronic structure and thus the highly efficient ORR performance can be achieved by axial Co-S.
基金supported by the National Natural Science Foundation of China(22275026 and 21805024)the Natural Science Foundation of Chongqing,China(cstc2021jcyj-msxm X0783,cstc2019jscx-msxm X0393 and cstc2018jcyj AX0461)+1 种基金the Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJZD-K202101303,KJQN201901335 and KJQN202001322)the Scientific Research Program of Chongqing Urban Administration(CGKZ2020-26)。
文摘Designing single-atom catalysts for oxygen reduction reaction(ORR)are fashionable but challenging to boost the zinc-air battery performance.Significantly enhanced ORR activity by manganese(Mn)singleatom catalysts can be achieved by accurately regulating the coordination number of isolated Mn atoms.Theoretical calculations indicate that the single Mn-N5sites possess lower free energy barrier and higher oxygen adsorption performance than single Mn-N4sites to accelerate the ORR kinetics.Target to it,here we synthesize an atomically dispersed Mn-N5catalyst by precisely axial coordination of pyridinic-N doped into two-dimensional(2D)porous nanocarbon sheets(~3.56 nm thickness),which reveals outstanding catalytic activity and ultrahigh stability for the ORR in zinc-air battery owing to the inhomogeneous charge distribution of Mn-N5sites compared to the conventional single-site Mn-N4catalyst and Pt/C.This work gives a new strategy for in situ regulating the electronic structure of metal single-atoms and further promoting the overall ORR performance in energy systems.
基金financially supported by the National Natural Science Foundation of China(grant nos.52073137 and 51763018).
文摘Metal porphyrins are star molecules that possess welldefined coordination metal centers for versatile catalytic reactions.However,most previous work has focused on the correlations between in-plane symmetric configuration of metal-N_(4)sites and their catalytic performance.Addressing the catalytic contribution of additional axial coordination to such symmetric configuration remains a challenge.Theoretical calculations revealed that axially anchoring an extra pyridine on the tetra-coordinated cobalt porphyrin(Co-N4)to construct penta-coordinated cobalt porphyrin(Co-N_(5))renders cobalt a higher electron density,thereby favoring the rate-determining O_(2)adsorption/activation and reducing the oxygen electroreduction barrier.Therefore,a well-defined Co-N_(5)site is rationally introduced into the azo-linked polymer framework for a fundamental structure-catalytic performance correlation study.As-prepared Co-N_(5)catalyst exhibits a 26 mV positive shift in half-wave potential compared with the pyridine-free Co-N_(4)counterpart,discloses a markedly higher power density(141.4 mW cm^(−2)),and possesses better long-term durability(over 160 h cycles)in a Zn-air battery.Moreover,such a Co-N_(5)catalyst also showcases potential applications for CO_(2)reduction with high CO_(2)-to-CO conversion faradic efficiency and better selectivity than the Co-N_(4)counterpart because coordination of the fifth pyridine evokes electronic localization that suppresses a competitive side reaction.This work proves the positive electrocatalytic contribution of axial penta-coordination on well-defined metalporphyrin-based catalysts and offers atomic understanding of the structure-performance correlation on single atom catalysts for future catalyst design.
文摘The axial coordination effect of F- on the redox behavior of (TPP)Co was investigated by F- titration with cyclic voltammetry detection and spectroeletrochemistry in dichloroethane .It was verified that mono(F-) axial adduct (TPP)Co(N ) (F- ) could be reduced at O. 1 V(SCE), and bis(F-) axial adduct (TPP)Co(Ⅲ ) (F-)2 formed with added Fmolar ratio>1 could be reduced at the potential <-0. 6 V(SCE). The equilibrium between (TPP)Co(Ⅲ) (F- ) and (TPP)Co (Ⅲ ) (F- )2 was demonstrated.
基金supported by the National Natural Science Foundation of China (Nos. 21705150 and 21473204)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China (No. 2021ZR124)
文摘The electrocatalysts containing cobalt-pyrrolic nitrogen-carbon(Co-N_(4)-C)moiety for CO_(2)reduction reaction(CO_(2)RR)have caught much attention.However;the effects of Co valence state and its synergy with gra-phene substrate are not clear yet.In this work;cobalt porphyrin(CoTPP)molecule with the intrinsic Co-N_(4)-C moiety is successfully combined with graphene oxide(GO)via three kinds of liquid-phase methods.The ratio of CoTPP to GO and the valence state of Co atom are studied to explore their catalysis for CO_(2)RR to CO.It is found that axial-ly-coordinated Co(III)TPPCl/GO nanocomposites synthesized via a chemical method exhibit better ability for CO_(2)RR;as compared with Co(II)TPP+GO and/or Co(III)TPPCl+GO nanocomposites obtained via a physically mixing way.After optimizing the ratio of CoTPP to GO;the Faradaic efficiency(FE)is more than 90%for CO_(2)RR to CO between−0.7 and−0.8 V vs.reversible hydrogen electrode(RHE)in Co(III)TPPCl/GO75.The synergy be-tween CoTPP and GO and the effect of Co valence state are systematically investigated;indicating that their strong interaction plays the key role in electrocatalytic CO_(2)RR.
