The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge d...The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge distribution of the traditional M-N_(4)active site,the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is difficult to reach the optimal value,which seriously limits the catalytic efficiency.The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N_(4)site,which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure.In this paper,we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C:metal site regulation,coordination number engineering,non-metal atom doping,and carbon support regulation.Through an in-depth analysis of the structure-activity relationship between the coordination configuration and catalytic performance,the core challenges faced by current research are pointed out,and future research directions are envisioned.This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.展开更多
Aqueous zinc-ion batteries are promising candidates as stationary storage systems for power-grid applications due to their high safety and low cost.The practical implementation of Zn-ion batteries currently still face...Aqueous zinc-ion batteries are promising candidates as stationary storage systems for power-grid applications due to their high safety and low cost.The practical implementation of Zn-ion batteries currently still faces formidable challenges because of Zn dendrite growth,hydrogen evolution,and inadequate environmental adaptability.Herein,to address these challenges,a strategy of regulation of water molecules coordination in electrolyte is proposed via developing a cross-linked hydrophilic hydrogel polymer electrolyte.Within this system,the continuous hydrogen bond among H_(2)O molecules is disrupted and the isolated H_(2)O molecules are strongly bound with a polymeric matrix comprised of polyacrylamide,carboxymethyl cellulose,and ethylene glycol,which can restrain the activity of H_(2)O molecules,thus effectively alleviating Zn dendrite growth and hydrogen evolution and enhancing the anti-freezing ability.With this electrolyte,the Zn||Cu cell presents a high coulombic efficiency of 99.4%over 900 cycles and Zn||Zn symmetric cell exhibits high cycling stability,maintaining plating/stripping for over 1,700 h.Moreover,the assembled Zn||PANI device also demonstrates outstanding electrochemical performance over a wide-temperature range,including a long cycling life over 14,120 cycles at room temperature and an ultralong cycling surpassing 30,000 cycles even at−40℃.This showcases the manipulation of water coordination chemistry for advanced,highly adaptable batteries.展开更多
Electrocatalytic reduction of nitrate pollutants to produce ammonia offers an effective approach to realizing the artificial nitrogen cycle and replacing the energyintensive Haber-Bosch process.Nitrite is an important...Electrocatalytic reduction of nitrate pollutants to produce ammonia offers an effective approach to realizing the artificial nitrogen cycle and replacing the energyintensive Haber-Bosch process.Nitrite is an important intermediate product in the reduction of nitrate to ammonia.Therefore,the mechanism of converting nitrite into ammonia warrants further investigation.Molecular cobalt catalysts are regarded as promising for nitrite reduction reactions(NO_(2)^(−)RR).However,designing and controlling the coordination environment of molecular catalysts is crucial for studying the mechanism of NO_(2)^(−)RR and catalyst design.Herein,we develop a molecular platform of cobalt porphyrin with three coordination microenvironments(Co-N_(3)X_(1),X=N,O,S).Electrochemical experiments demonstrate that cobalt porphyrin with O coordination(CoOTPP)exhibits the lowest onset potential and the highest activity for NO_(2)^(−)RR in ammonia production.Under neutral,nonbuffered conditions over a wide potential range(−1.0 to−1.5 V versus AgCl/Ag),the Faradaic efficiency of nearly 90%for ammonia was achieved and reached 94.5%at−1.4 V versus AgCl/Ag,with an ammonia yield of 6,498μgh^(−1)and a turnover number of 22,869 at−1.5V versus AgCl/Ag.In situ characterization and density functional theory calculations reveal that modulating the coordination environment alters the electron transfer mode of the cobalt active center and the charge redistribution caused by the break of the ligand field.Therefore,this results in enhanced electrochemical activity for NO_(2)^(−)RR in ammonia production.This study provides valuable guidance for designing adjustments to the coordination environment of molecular catalysts to enhance catalytic activity.展开更多
The structural complexity of supported metal catalysts,playing significant role in a wide range of chemical technologies,have prevented us from deeply understanding their catalytic mechanisms at atomic level.A fundame...The structural complexity of supported metal catalysts,playing significant role in a wide range of chemical technologies,have prevented us from deeply understanding their catalytic mechanisms at atomic level.A fundamental understanding of the nature of active sites and structure–performance relationship of supported metal catalysts from a comprehensive view will open up numerous new opportunities for the development of advanced catalysts to address the global challenges in energy conversion and environmental protection.This review surveys the effects of multiple factors,including the metal size,shape,support,alloy and ligand modifier,on the coordinated environment of active center and further their influence on the catalytic reactions,aiming to provide guidance for the design of industrialized heterogeneous catalysts with extraordinary performance.Subsequently,the key structure characterization techniques in determining the coordination structure of active metal sites,especially the dynamic coordination structure change under the reaction condition,are well summarized.A brief summary is finally provided together with personal perspectives on the further development in the field of heterogeneous metal catalysts.展开更多
Rh single atom catalysts(SACs)have been insensitively investigated recently due to the maximum utilization efficiency of Rh,one of the most expensive precious metals.Although great efforts have been made in the develo...Rh single atom catalysts(SACs)have been insensitively investigated recently due to the maximum utilization efficiency of Rh,one of the most expensive precious metals.Although great efforts have been made in the development and application of Rh SACs,there are few reports on the precise control of the local coordination environment of Rh single sites on CeO_(2) and their catalytic performance for N_(2)O decomposition.Herein,Rh/CeO_(2) catalysts with different Rh-O coordination numbers(CNs)were successfully prepared using different CeO_(2) supports and a simple incipient wetness impregnation(IWI)method.It is observed that the Rh/CeO_(2) catalyst with slightly higher CN of Rh-O(Rh/CeO_(2)-H)prepared from CeO_(2) shows much higher N_(2)O decomposition activity than the catalyst with lower CN of Rh-O(Rh/CeO_(2)-L)obtained from Ce(OH)_(x).The Rh species within Rh/CeO_(2)-H are found to be more reactive than those within Rh/CeO_(2)-L,which can better facilitate the O_(2)desorption once formed during N_(2)O deco mposition.In additio n,more surface oxygen vacancies are present on Rh/CeO_(2)-H than on Rh/CeO_(2)-L,well explaining the superior N_(2)O adsorption and activation capability on the former catalyst.It is concluded that more abundant oxygen vacancies and reactive Rh single atom sites with slightly higher CN of Rh-O and significantly higher reducibility altogether contribute to the superior N_(2)O decomposition activity on the Rh/CeO_(2)-H catalyst.展开更多
In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The ...In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.展开更多
Single‐atom catalysts have been proposed as promising electrocatalysts for CO_(2) reduction reactions(CO_(2)RR).Co‐N_(4) active sites have attracted wide attention owing to their excellent CO selectivity and activit...Single‐atom catalysts have been proposed as promising electrocatalysts for CO_(2) reduction reactions(CO_(2)RR).Co‐N_(4) active sites have attracted wide attention owing to their excellent CO selectivity and activity.However,the effect of the local coordination environment of Co sites on CO_(2) reduction reaction pathways is still unclear.In this study,we investigated the CO_(2) reduction reaction pathways on Co‐N_(4) sites supported on conjugated N_(4)‐macrocyclic ligands with 1,10‐phenanthroline subunits(Co‐N_(4)‐CPY)by density functional theory calculations.The local coordination environment of single‐atom Co sites with N substituted by O(Co‐N_(3)O‐CPY)and C(Co‐N_(3)C‐CPY)was studied for comparison.The calculation results revealed that both C and O coordination break the symmetry of the primary CoN_(4) ligand field and induce charge redistribution of the Co atom.For Co‐N_(4)‐CPY,CO was confirmed to be the main product of CO_(2)RR.HCOOH is the primary product of Co‐N_(3)O‐CPY because of the greatly increased energy barrier of CO_(2) to*COOH.Although the energy barrier of CO_(2) to*COOH is reduced on Co‐N_(3)C‐CPY,the desorption process of*CO becomes more difficult.CH3OH(or CH_(4))are obtained by further*CO hydrogenation reduction when using Co‐N_(3)C‐CPY.This work provides new insight into the effect of the local coordination environment of single‐atom sites on CO_(2) reduction reaction pathways.展开更多
Aqueous Zn-ion batteries(AZIBs)are the potential options for the next-generation energy storage scenarios due to the cost effectiveness and intrinsic safety.Nevertheless,the industrial application of AZIBs is still im...Aqueous Zn-ion batteries(AZIBs)are the potential options for the next-generation energy storage scenarios due to the cost effectiveness and intrinsic safety.Nevertheless,the industrial application of AZIBs is still impeded by a series of parasitic reactions and dendrites at zinc anodes.In this study,taurine(TAU)is used in electrolyte to simultaneously optimize the coordination condition of the ZnSO4electrolyte and interfacial chemistry at the anode.TAU can preferentially adsorb with the zinc metal and induce an in situ stable and protective interface on the anode,which would avoid the connection between H_(2)O and the zinc metal and promote the even deposition of Zn^(2+).The resulting Zn//Zn batteries achieve more than 3000 hours long cyclic lifespan under 1 mA cm^(-2)and an impressive cumulative capacity at 5 mA cm^(-2).Moreover,Zn//Cu batteries can realize a reversible plating/stripping process over 2,400cycles,with a desirable coulombic efficiency of 99.75%(1 mA cm^(-2)).Additionally,the additive endows Zn//NH_(4)V_(4)O_(10)batteries with more stable cyclic performance and ultrafast rate capability.These capabilities can promote the industrial application of AZIBs.展开更多
Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction(HER)play crucial role in the growing hydrogen economy.Recently,the atomically dispersed metal catalysts hav...Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction(HER)play crucial role in the growing hydrogen economy.Recently,the atomically dispersed metal catalysts have attracted increasing attention due to their ultimate atom utilization and great potential for highly cost-effective and high-efficiency HER electrocatalyst.Herein,we propose a hightemperature treatment strategy to furtherly improve the HER performance of atomically dispersed Ptbased catalyst.Interestingly,after appropriate high-temperature treatment on the atomically dispersed Pt0.8@CN,the Pt species on the designed N-doped porous carbon substrate with rich defect sites can be re-dispersed to single atom state with new coordination environment.The obtained Pt0.8@CN-1000 shows superior HER performance with overpotential of 13 m V at 10 m A cm^(-2)and mass activity of 11,284 m A/mgPtat-0.1 V,much higher than that of the pristine Pt0.8@CN and commercial Pt/C catalyst.The experimental and theoretical investigations indicate that the high-temperature treatment induces the restructuring of coordination environment and then the optimized Pt electronic state leads to the enhanced HER performances.This work affords new strategy and insights to develop the atomically dispersed high-efficiency catalysts.展开更多
Single-atom catalysts(SACs),with atomically dispersed metal atoms anchored on a typical support,representing the utmost utilization effi ciency of the atoms,have recently emerged as promising catalysts for a variety o...Single-atom catalysts(SACs),with atomically dispersed metal atoms anchored on a typical support,representing the utmost utilization effi ciency of the atoms,have recently emerged as promising catalysts for a variety of catalytic applications.The electronic properties of the active center of SACs are highly dependent on the local environment constituted by the single metal atom and its surrounding coordination elements.Therefore,engineering the coordination environment near single metal sites,from the fi rst coordination shell to the second shell or higher,would be a rational way to design effi cient SACs with optimized electronic structure for catalytic applications.The wide range of coordination confi gurations,guaranteed by the multiple choices of the type and heterogeneity of the coordination element(N,O,P,S,etc.),further off er a large opportunity to rationally design SACs for satisfactory activities and investigate the structure-performance relationship.In this review,the coordination engineering of SACs by varying the type of coordination element was elaborated and the photocatalytic water splitting of SACs was highlighted.Finally,challenging issues related to the coordination engineering of SACs and their photocatalytic applications were discussed to call for more eff orts devoted to the further development of single-atom catalysis.展开更多
Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO...Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO lattice and manipulate the magnetic properties of Mn-doped ZnO. Mn ions initially enter into interstitial sites and a Mn3＋ 06 octahedral coordination is produced in the prepared Mn-doped ZnO sample, in which the nearest neighbor Mn3＋ and 02 ions could form a Mn3＋-O2--Mn3＋ complex. After H2 annealing, interstitial Mn ions can substitute for Zn to generate the Mn2＋O4 tetrahedral coordination in the nanocrystals, in which neighboring Mn2＋ ions and H atoms could form a Mn2＋-O2--Mn2＋ complex and Mn-H-Mn bridge structure. The magnetic measurement of the as-prepared sample shows room temperature paramagnetic behavior due to the Mn3＋-O2--Mn3＋ complex, while the annealed samples exhibit their ferromagnetism, which originates from the Mn-H-Mn bridge structure and the Mn-Mn exchange interaction in the Mn2＋-O2--Mn2＋ complex.展开更多
Single-atom catalysts(SACs)have attracted significant attention due to their high atomic utilization and tunable coordination environment.However,the catalytic mechanisms related to the active center and coordination ...Single-atom catalysts(SACs)have attracted significant attention due to their high atomic utilization and tunable coordination environment.However,the catalytic mechanisms related to the active center and coordination environment remain unclear.In this study,we systematically investigated the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)catalytic activities of NiN_(4),NiN_(3),NiN_(3)H_(2),NiN_(4)X,NiN_(3)X,and NiN_(3)H_(2)X(X denotes axial ligand)through density functional theory(DFT)calculations.This study unveils two distinct reaction pathways for ORR and OER,involving proton-electron pairs adsorbed from both the solution and the catalyst surface.The overpotential is the key parameter to evaluate the catalytic performance when proton-electron pairs are adsorbed from the solution.NiN_(3)and NiN_(3)H_(2)show promise as pH-universal bifunctional electrocatalysts for both ORR and OER.On the other hand,when proton-electron pairs are adsorbed from the catalyst surface,the reaction energy barrier becomes the crucial metric for assessing catalytic activity.Our investigation reveals that NiN_(3)H_(2)consistently exhibits optimal ORR activity across a wide pH range,regardless of the source of proton-electron pair(solvent or catalyst surface).展开更多
Carbon-based materials are recognized as anodes fulling of promise for potassium ion batteries(PIBs)due to advantages of affordable cost and high conductivity.However,they still face challenges including structural un...Carbon-based materials are recognized as anodes fulling of promise for potassium ion batteries(PIBs)due to advantages of affordable cost and high conductivity.However,they still face challenges including structural unstability and slow kinetics.It is difficult to achieve efficient potassium storage with unmodified carbonaceous anode.Herein,atomic bismuth(Bi)sites with different atom coordinations anchored on carbon nanosheets(CNSs)have been synthesized through a template method.The properties of prepared multi-doping carbon anodes Bi-N_(3)S_(1)/CNSs,Bi-N_(3)P_(1)/CNSs and Bi-N_(4)/CNSs were probed in PIBs.The configuration Bi-N_(3)S_(1) with stronger charge asymmetry exhibits superior potassium storage performance compared to Bi-N_(3)P_(1) and Bi-N_(4) configurations.The Bi-N_(3)S_(1)/CNSs display a rate capacity of 129.2 mAh g^(-1)even at 10 A g^(-1)and an impressive cyclability characterized by over 5000 cycles at 5 A g^(-1),on account of its optimal coordination environment with more active Bi centers and K^(+)adsorption sites.Notably,assembled potassium-ion full cell Mg-KVO//Bi-N_(3)S_(1)/CNSs also shows an outstanding cycling stability,enduring 3000 cycles at 2 A g^(-1).Therefore,it can be demonstrated that regulating the electronic structure of metallic centre M-N_(4) via changing the type of ligating atom is a feasible strategy for modifying carbon anodes,on the base of co-doping metal and non-metal.展开更多
Pt single atoms catalysts with precise coordination environment and high stability are expected to achieve high performance of propane dehydrogenation(PDH).In this work,an innovative synthetic strategy is proposed to ...Pt single atoms catalysts with precise coordination environment and high stability are expected to achieve high performance of propane dehydrogenation(PDH).In this work,an innovative synthetic strategy is proposed to construct the S-1@0.1Pt9Zn@DPS-1 nanocomposite as a highly efficient PDH catalyst.Defect engineering is applied to induce the formation of defective porous silicalite-1(DPS-1),which is favorable for achieving the uniformly distributed ZnO nanoclusters.The ZnO nanoclusters were further served as anchoring sites to stabilize the isolated Pt atoms.The structural characterization revealed that penta-O coordinated Pt single atom coupled with ZnO nanoclusters decorated on the DPS-1.Moreover,the atomically dispersed Pt atoms with the ideal coordination environment could act as the predominant active sites for PDH process.As expected,the optimal S-1@0.1Pt9Zn@DPS-1 catalyst delivered an excellent PDH performance(propane conversion of 40.7%,propylene selectivity of 97.5%)and good cycling regeneration stability.This work provides a new way for improving the activity and stability of catalysts in the field of industrial catalysts.展开更多
The electrocatalytic CO_(2) reduction reaction(CO_(2)RR)represents an effective way to address energy crises and environmental issues by converting CO_(2) into valuable chemicals.Single-atom catalysts(SACs)can achieve...The electrocatalytic CO_(2) reduction reaction(CO_(2)RR)represents an effective way to address energy crises and environmental issues by converting CO_(2) into valuable chemicals.Single-atom catalysts(SACs)can achieve excellent catalytic activity in CO_(2)RR.However,the study of CO_(2)RR on SACs still poses significant challenges,especially in terms of controlling the selectivity towards the deep product such as CH4 and CH3OH.Herein,we employ density functional theory(DFT)calculations to investigate the CO_(2)RR on Cu SAC supported on N-doped graphene(Cu-N/C)and explore the role of N dopants on the CO_(2)RR performance.Compared to Cu SACs sup-ported on N-doped defective graphene with double vacancy(Cu-N/C-DV),Cu SACs supported on N-doped defective graphene with single vacancy(Cu-N/C-SV)can effectively convert CO_(2) into the deeply reduced C1 products,including CH_(4) and CH_(3)OH,thus further indicating that Cu-N/C-SV has a stronger interaction with*CO,which is conducive to the deep reduction of*CO.Increasing the coordination number of N atoms or the proximity of doping site to the Cu active site can effectively enhance the stability of catalyst and promote the adsorption of*CO on Cu-N/C-SV.However,this also increases the free energy of the formation of*CHO intermediate.The results suggest that CuC3-Nm,which contains a N atom in the second coordination shell(meta-position)of Cu SACs,has the best electrocatalytic performance of CO_(2)RR in terms of both selectivity and catalytic activity,not only contributing to an in-depth understanding of the reaction mechanism of CO_(2)RR on SACs but also providing insights into the design of SACs for efficient CO_(2)RR.展开更多
The local coordination environment of catalysts has been investigated ftor an extended period to obtain enhanced catalytic performance.Especially with the advancement of single-atom catalysts(SACs),research on the coo...The local coordination environment of catalysts has been investigated ftor an extended period to obtain enhanced catalytic performance.Especially with the advancement of single-atom catalysts(SACs),research on the coordination environment has been advanced to the atomic level.The surrounding coordination atoms of central metal atoms play important roles in their catalytic activity,selectivity and stability.In recent years,remarkable improvements of the catalytic performance of SACs have been achieved by the tailoring of coordination atoms,coordination numbers and second-or higher-coordination shells,which provided new opportunities for the further development of SACs.In this review,the characterization of coordination environment,tailoring of the local coordination environment,and their related adjustable catalytic performance will be discussed.We hope this review will provide new insights on further research of SACs.展开更多
Fine-tuning of the coordination environment of single-atom catalysts(SACs)is effective to optimize their catalytic performances,yet it remains challenging due to the vulnerability of SACs.Herein,we report a new approa...Fine-tuning of the coordination environment of single-atom catalysts(SACs)is effective to optimize their catalytic performances,yet it remains challenging due to the vulnerability of SACs.Herein,we report a new approach to engineering the coordination environment of M-N-C(M=Fe,Co,and Ni)SACs by using glutamic acid as the N/C source and pyrolysis atmosphere as a regulator.Compared with that in N2,NH3 was able to promote the doping of N at 7<700℃yet etch the N-species at higher temperatures,by which the M-N coordination number(CN)and the electronic structure were delicately tuned.It was found that the electron density of Ni single atoms increased with the decrease of Ni-N CN.As a consequence,the capability of Ni-N-C to dissociate H2 was greatly enhanced and a higher catalytic activity in chemoselective hydrogenation of functionalized nitroarenes was achieved.Moreover,this modulation method could be applied to other transition metals including Fe and Co.In particular,the as-synthesized Co-N-C SAC afforded a turnover frequency of 152.3 h~1 with 99%selectivity to 3-vinylaniline in the hydrogenation of 3-nitrostyrene,which was the highest ever reported thus far and was at least one order of magnitude more active than state-of-the-art noble-metal-free M-N-C catalysts,demonstrating the great potential of engineering the coordination environment of SACs.展开更多
Fe-N-C catalysts represent very promising cathode catalysts for polymer electrolyte fuel cells,owing to their outstanding activity for the oxygen reduction reaction(ORR),especially in alkaline media.In this review,we ...Fe-N-C catalysts represent very promising cathode catalysts for polymer electrolyte fuel cells,owing to their outstanding activity for the oxygen reduction reaction(ORR),especially in alkaline media.In this review,we summarize recent advances in the design and synthesis of Fe-N-C catalysts rich in highly dispersed FeNx active sites.Special emphasis is placed on emerging strategies for tuning the electronic structure of the Fe atoms to enhance the ORR activity,and also maximizing the surface concentration of FeNx sites that are catalytically accessible during ORR.While great progress has been made over the past 5 years in the development of Fe-N-C catalyst for ORR,significant technical obstacles still need to be overcome to enable the large-scale application of Fe-N-C materials as cathode catalysts in real-world fuel cells.展开更多
Designing highly efficient bifunctional electrocatalysts for oxygen reduction and evolution reaction(ORR/OER)is extremely important for developing regenerative fuel cells and metal-air batteries.Single-atom catalysts(...Designing highly efficient bifunctional electrocatalysts for oxygen reduction and evolution reaction(ORR/OER)is extremely important for developing regenerative fuel cells and metal-air batteries.Single-atom catalysts(SACs)have gained considerable attention in recent years because of their maximum atom utilization efficiency and tunable coordination environments.Herein,through density functional theory(DFT)calculations,we systematically explored the ORR/OER performances of nitrogencoordinated transition metal carbon materials(TM-N_(x)-C(TM=Mn,Fe,Co,Ni,Cu,Pd,and Pt;x=3,4))through tailoring the coordination environment.Our results demonstrate that compared to conventional tetra-coordinated(TM-N_(4)-C)catalysts,the asymmetric tri-coordinated(TM-N_(3)-C)catalysts exhibit stronger adsorption capacity of catalytic intermediates.Among them,Ni-N_(3)-C possesses optimal adsorption energy and the lowest overpotential of 0.29 and 0.28 V for ORR and OER,respectively,making it a highly efficient bifunctional catalyst for oxygen catalysis.Furthermore,we find this enhanced effect stems from the additional orbital interaction between newly uncoordinated d-orbitals and p-orbitals of oxygenated species,which is evidently testified via the change of d-band center and integral crystal orbital Hamilton population(ICOHP).This work not only provides a potential bifunctional oxygen catalyst,but also enriches the knowledge of coordination engineering for tailoring the activity of SACs,which may pave the way to design and discover more promising bifunctional electrocatalysts for oxygen catalysis.展开更多
The mechanism governing the pseudocapacitive lithium storage behavior is one of the most critical unsolved issues in conversion-type anodes for lithium-ion batteries.In this work,we,for the first time,demonstrate that...The mechanism governing the pseudocapacitive lithium storage behavior is one of the most critical unsolved issues in conversion-type anodes for lithium-ion batteries.In this work,we,for the first time,demonstrate that the pseudocapacitive capability of iron oxide-based anodes is closely associated with the electronic structures of iron ions.As proof of concept,the introduction of amorphization,nitrogen doping,oxygen vacancies reduces the coordination of iron ions and contributes significantly to the pseudocapacitive lithium storage capability of iron oxide,reaching up to 96%of the specific capacity at 1 mV·s^(−1).Due to the significantly modulated coordination environment,the 3d electrons of Fe(II)are delocalized with increased spin state and the energy band gap is narrowed,accompanied by an upshift of Fermi energy.The redox activity and carrier mobility of iron oxides are substantially increased,which substantially enhance the exchange current density and thereby improve the pseudocapacitive capability of iron oxide.展开更多
基金supported by the Natural Science Foundation of Hebei Province(no.E2024501010)the National Natural Science Foundation of China(no.52374301)+1 种基金the Shijiazhuang Basic Research Project(no.241790667A)the Performance Subsidy Fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(no.22567627H)。
文摘The development of highly efficient non-precious metal-nitrogen-carbon(M-N-C)electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells.Due to the symmetric charge distribution of the traditional M-N_(4)active site,the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is difficult to reach the optimal value,which seriously limits the catalytic efficiency.The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N_(4)site,which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure.In this paper,we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C:metal site regulation,coordination number engineering,non-metal atom doping,and carbon support regulation.Through an in-depth analysis of the structure-activity relationship between the coordination configuration and catalytic performance,the core challenges faced by current research are pointed out,and future research directions are envisioned.This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.
基金the financial support from Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515012077)National Natural Science Foundation of China(No.52401296)+3 种基金the financial support by Guangdong Provincial Pearl River Talents Program(Grant No.2023CX10L019)Bureau of Science and Technology of Jiangmen Municipality(Grant No.2320002001062)And this work is also partly supported by Guangdong S&T Programme(No.2022B1212040001)Guangdong-Hong Kong-Macao joint Laboratory(No.2023B1212120003).
文摘Aqueous zinc-ion batteries are promising candidates as stationary storage systems for power-grid applications due to their high safety and low cost.The practical implementation of Zn-ion batteries currently still faces formidable challenges because of Zn dendrite growth,hydrogen evolution,and inadequate environmental adaptability.Herein,to address these challenges,a strategy of regulation of water molecules coordination in electrolyte is proposed via developing a cross-linked hydrophilic hydrogel polymer electrolyte.Within this system,the continuous hydrogen bond among H_(2)O molecules is disrupted and the isolated H_(2)O molecules are strongly bound with a polymeric matrix comprised of polyacrylamide,carboxymethyl cellulose,and ethylene glycol,which can restrain the activity of H_(2)O molecules,thus effectively alleviating Zn dendrite growth and hydrogen evolution and enhancing the anti-freezing ability.With this electrolyte,the Zn||Cu cell presents a high coulombic efficiency of 99.4%over 900 cycles and Zn||Zn symmetric cell exhibits high cycling stability,maintaining plating/stripping for over 1,700 h.Moreover,the assembled Zn||PANI device also demonstrates outstanding electrochemical performance over a wide-temperature range,including a long cycling life over 14,120 cycles at room temperature and an ultralong cycling surpassing 30,000 cycles even at−40℃.This showcases the manipulation of water coordination chemistry for advanced,highly adaptable batteries.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFC2105800National Natural Science Foundation of China,Grant/Award Numbers:21901084,21905106,22279041+2 种基金Higher Education Discipline Innovation Project,Grant/Award Number:B17020Specific Research Fund of the Innovation Platform for Academicians of Hainan Province,China,Grant/Award Number:YSPTZX202321Natural Science Foundation of Jilin Province,Grant/Award Number:SKL202302017.
文摘Electrocatalytic reduction of nitrate pollutants to produce ammonia offers an effective approach to realizing the artificial nitrogen cycle and replacing the energyintensive Haber-Bosch process.Nitrite is an important intermediate product in the reduction of nitrate to ammonia.Therefore,the mechanism of converting nitrite into ammonia warrants further investigation.Molecular cobalt catalysts are regarded as promising for nitrite reduction reactions(NO_(2)^(−)RR).However,designing and controlling the coordination environment of molecular catalysts is crucial for studying the mechanism of NO_(2)^(−)RR and catalyst design.Herein,we develop a molecular platform of cobalt porphyrin with three coordination microenvironments(Co-N_(3)X_(1),X=N,O,S).Electrochemical experiments demonstrate that cobalt porphyrin with O coordination(CoOTPP)exhibits the lowest onset potential and the highest activity for NO_(2)^(−)RR in ammonia production.Under neutral,nonbuffered conditions over a wide potential range(−1.0 to−1.5 V versus AgCl/Ag),the Faradaic efficiency of nearly 90%for ammonia was achieved and reached 94.5%at−1.4 V versus AgCl/Ag,with an ammonia yield of 6,498μgh^(−1)and a turnover number of 22,869 at−1.5V versus AgCl/Ag.In situ characterization and density functional theory calculations reveal that modulating the coordination environment alters the electron transfer mode of the cobalt active center and the charge redistribution caused by the break of the ligand field.Therefore,this results in enhanced electrochemical activity for NO_(2)^(−)RR in ammonia production.This study provides valuable guidance for designing adjustments to the coordination environment of molecular catalysts to enhance catalytic activity.
文摘The structural complexity of supported metal catalysts,playing significant role in a wide range of chemical technologies,have prevented us from deeply understanding their catalytic mechanisms at atomic level.A fundamental understanding of the nature of active sites and structure–performance relationship of supported metal catalysts from a comprehensive view will open up numerous new opportunities for the development of advanced catalysts to address the global challenges in energy conversion and environmental protection.This review surveys the effects of multiple factors,including the metal size,shape,support,alloy and ligand modifier,on the coordinated environment of active center and further their influence on the catalytic reactions,aiming to provide guidance for the design of industrialized heterogeneous catalysts with extraordinary performance.Subsequently,the key structure characterization techniques in determining the coordination structure of active metal sites,especially the dynamic coordination structure change under the reaction condition,are well summarized.A brief summary is finally provided together with personal perspectives on the further development in the field of heterogeneous metal catalysts.
基金Project supported by the Startup Fund(F.L.)from the University of Central Florida(UCF)National Science Foundation grants(CHE-1955343,DMR-1920050).
文摘Rh single atom catalysts(SACs)have been insensitively investigated recently due to the maximum utilization efficiency of Rh,one of the most expensive precious metals.Although great efforts have been made in the development and application of Rh SACs,there are few reports on the precise control of the local coordination environment of Rh single sites on CeO_(2) and their catalytic performance for N_(2)O decomposition.Herein,Rh/CeO_(2) catalysts with different Rh-O coordination numbers(CNs)were successfully prepared using different CeO_(2) supports and a simple incipient wetness impregnation(IWI)method.It is observed that the Rh/CeO_(2) catalyst with slightly higher CN of Rh-O(Rh/CeO_(2)-H)prepared from CeO_(2) shows much higher N_(2)O decomposition activity than the catalyst with lower CN of Rh-O(Rh/CeO_(2)-L)obtained from Ce(OH)_(x).The Rh species within Rh/CeO_(2)-H are found to be more reactive than those within Rh/CeO_(2)-L,which can better facilitate the O_(2)desorption once formed during N_(2)O deco mposition.In additio n,more surface oxygen vacancies are present on Rh/CeO_(2)-H than on Rh/CeO_(2)-L,well explaining the superior N_(2)O adsorption and activation capability on the former catalyst.It is concluded that more abundant oxygen vacancies and reactive Rh single atom sites with slightly higher CN of Rh-O and significantly higher reducibility altogether contribute to the superior N_(2)O decomposition activity on the Rh/CeO_(2)-H catalyst.
基金supported by the National Natural Science Foundation of China (NSFC,22172082,21978137,22102074,and 21878162)Natural Science Foundation of Tianjin (20JCZDJC00770)+1 种基金Postdoctoral Research Foundation of China (2021M701776)NCC Fund (NCC2020FH05)。
文摘In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.
文摘Single‐atom catalysts have been proposed as promising electrocatalysts for CO_(2) reduction reactions(CO_(2)RR).Co‐N_(4) active sites have attracted wide attention owing to their excellent CO selectivity and activity.However,the effect of the local coordination environment of Co sites on CO_(2) reduction reaction pathways is still unclear.In this study,we investigated the CO_(2) reduction reaction pathways on Co‐N_(4) sites supported on conjugated N_(4)‐macrocyclic ligands with 1,10‐phenanthroline subunits(Co‐N_(4)‐CPY)by density functional theory calculations.The local coordination environment of single‐atom Co sites with N substituted by O(Co‐N_(3)O‐CPY)and C(Co‐N_(3)C‐CPY)was studied for comparison.The calculation results revealed that both C and O coordination break the symmetry of the primary CoN_(4) ligand field and induce charge redistribution of the Co atom.For Co‐N_(4)‐CPY,CO was confirmed to be the main product of CO_(2)RR.HCOOH is the primary product of Co‐N_(3)O‐CPY because of the greatly increased energy barrier of CO_(2) to*COOH.Although the energy barrier of CO_(2) to*COOH is reduced on Co‐N_(3)C‐CPY,the desorption process of*CO becomes more difficult.CH3OH(or CH_(4))are obtained by further*CO hydrogenation reduction when using Co‐N_(3)C‐CPY.This work provides new insight into the effect of the local coordination environment of single‐atom sites on CO_(2) reduction reaction pathways.
基金supported by the State Key Laboratorys of Electrical Insulation and Power Equipment(EIPE23308)the Young Talent Recruiting Plans of Xi’an Jiaotong University(DQ6J012)+2 种基金the Fundamental Research Funds for the Central Universities(xtr042021008,xzy022022049)the Natural Science Basic Research Plan in Shaanxi Province of China(2023-JC-QN-0587)the“Young Talent Support Plan”of Xi’an Jiaotong University。
文摘Aqueous Zn-ion batteries(AZIBs)are the potential options for the next-generation energy storage scenarios due to the cost effectiveness and intrinsic safety.Nevertheless,the industrial application of AZIBs is still impeded by a series of parasitic reactions and dendrites at zinc anodes.In this study,taurine(TAU)is used in electrolyte to simultaneously optimize the coordination condition of the ZnSO4electrolyte and interfacial chemistry at the anode.TAU can preferentially adsorb with the zinc metal and induce an in situ stable and protective interface on the anode,which would avoid the connection between H_(2)O and the zinc metal and promote the even deposition of Zn^(2+).The resulting Zn//Zn batteries achieve more than 3000 hours long cyclic lifespan under 1 mA cm^(-2)and an impressive cumulative capacity at 5 mA cm^(-2).Moreover,Zn//Cu batteries can realize a reversible plating/stripping process over 2,400cycles,with a desirable coulombic efficiency of 99.75%(1 mA cm^(-2)).Additionally,the additive endows Zn//NH_(4)V_(4)O_(10)batteries with more stable cyclic performance and ultrafast rate capability.These capabilities can promote the industrial application of AZIBs.
基金financially supported by the National Science Foundation of China(21773112,21173119,and 21273109)the National Key Technology R&D Program of China(2017YFB0310704)the Fundamental Research Funds for the Central Universities and the Hubei Key Laboratory for Processing and Application of Catalytic Materials(CH201401)。
文摘Development of high-performance and cost-effective catalysts for electrocatalytic hydrogen evolution reaction(HER)play crucial role in the growing hydrogen economy.Recently,the atomically dispersed metal catalysts have attracted increasing attention due to their ultimate atom utilization and great potential for highly cost-effective and high-efficiency HER electrocatalyst.Herein,we propose a hightemperature treatment strategy to furtherly improve the HER performance of atomically dispersed Ptbased catalyst.Interestingly,after appropriate high-temperature treatment on the atomically dispersed Pt0.8@CN,the Pt species on the designed N-doped porous carbon substrate with rich defect sites can be re-dispersed to single atom state with new coordination environment.The obtained Pt0.8@CN-1000 shows superior HER performance with overpotential of 13 m V at 10 m A cm^(-2)and mass activity of 11,284 m A/mgPtat-0.1 V,much higher than that of the pristine Pt0.8@CN and commercial Pt/C catalyst.The experimental and theoretical investigations indicate that the high-temperature treatment induces the restructuring of coordination environment and then the optimized Pt electronic state leads to the enhanced HER performances.This work affords new strategy and insights to develop the atomically dispersed high-efficiency catalysts.
基金the National Natural Science Foundation of China(Nos.21805191 and 21972094)the Guangdong Basic and Applied Basic Research Founda-tion(No.2020A1515010982)+1 种基金Shenzhen Pengcheng Scholar Program,Shenzhen Peacock Plan(No.KQTD2016053112042971)Shenzhen Science and Technology Program(Nos.KQJSCX20170727100802505 and RCJC20200714114434086).
文摘Single-atom catalysts(SACs),with atomically dispersed metal atoms anchored on a typical support,representing the utmost utilization effi ciency of the atoms,have recently emerged as promising catalysts for a variety of catalytic applications.The electronic properties of the active center of SACs are highly dependent on the local environment constituted by the single metal atom and its surrounding coordination elements.Therefore,engineering the coordination environment near single metal sites,from the fi rst coordination shell to the second shell or higher,would be a rational way to design effi cient SACs with optimized electronic structure for catalytic applications.The wide range of coordination confi gurations,guaranteed by the multiple choices of the type and heterogeneity of the coordination element(N,O,P,S,etc.),further off er a large opportunity to rationally design SACs for satisfactory activities and investigate the structure-performance relationship.In this review,the coordination engineering of SACs by varying the type of coordination element was elaborated and the photocatalytic water splitting of SACs was highlighted.Finally,challenging issues related to the coordination engineering of SACs and their photocatalytic applications were discussed to call for more eff orts devoted to the further development of single-atom catalysis.
基金supported by the National Basic Research Program of China(Grant No.2013CB934001)the National Natural Science Foundation of China(Grant Nos.51072012 and 51272015)
文摘Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO lattice and manipulate the magnetic properties of Mn-doped ZnO. Mn ions initially enter into interstitial sites and a Mn3＋ 06 octahedral coordination is produced in the prepared Mn-doped ZnO sample, in which the nearest neighbor Mn3＋ and 02 ions could form a Mn3＋-O2--Mn3＋ complex. After H2 annealing, interstitial Mn ions can substitute for Zn to generate the Mn2＋O4 tetrahedral coordination in the nanocrystals, in which neighboring Mn2＋ ions and H atoms could form a Mn2＋-O2--Mn2＋ complex and Mn-H-Mn bridge structure. The magnetic measurement of the as-prepared sample shows room temperature paramagnetic behavior due to the Mn3＋-O2--Mn3＋ complex, while the annealed samples exhibit their ferromagnetism, which originates from the Mn-H-Mn bridge structure and the Mn-Mn exchange interaction in the Mn2＋-O2--Mn2＋ complex.
基金supported by Scientific and Technological Project of Yunnan Precious Metals Laboratory(No.YPML-2023050234)Major Science and Technology Programs of Yunnan(Nos.202302AH360001 and 202307AC110005).
文摘Single-atom catalysts(SACs)have attracted significant attention due to their high atomic utilization and tunable coordination environment.However,the catalytic mechanisms related to the active center and coordination environment remain unclear.In this study,we systematically investigated the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)catalytic activities of NiN_(4),NiN_(3),NiN_(3)H_(2),NiN_(4)X,NiN_(3)X,and NiN_(3)H_(2)X(X denotes axial ligand)through density functional theory(DFT)calculations.This study unveils two distinct reaction pathways for ORR and OER,involving proton-electron pairs adsorbed from both the solution and the catalyst surface.The overpotential is the key parameter to evaluate the catalytic performance when proton-electron pairs are adsorbed from the solution.NiN_(3)and NiN_(3)H_(2)show promise as pH-universal bifunctional electrocatalysts for both ORR and OER.On the other hand,when proton-electron pairs are adsorbed from the catalyst surface,the reaction energy barrier becomes the crucial metric for assessing catalytic activity.Our investigation reveals that NiN_(3)H_(2)consistently exhibits optimal ORR activity across a wide pH range,regardless of the source of proton-electron pair(solvent or catalyst surface).
基金financially supported by the National Natural Science Foundation of China(22209057)the Guangzhou Basic and Applied Basic Research Foundation(2024A04J0839)。
文摘Carbon-based materials are recognized as anodes fulling of promise for potassium ion batteries(PIBs)due to advantages of affordable cost and high conductivity.However,they still face challenges including structural unstability and slow kinetics.It is difficult to achieve efficient potassium storage with unmodified carbonaceous anode.Herein,atomic bismuth(Bi)sites with different atom coordinations anchored on carbon nanosheets(CNSs)have been synthesized through a template method.The properties of prepared multi-doping carbon anodes Bi-N_(3)S_(1)/CNSs,Bi-N_(3)P_(1)/CNSs and Bi-N_(4)/CNSs were probed in PIBs.The configuration Bi-N_(3)S_(1) with stronger charge asymmetry exhibits superior potassium storage performance compared to Bi-N_(3)P_(1) and Bi-N_(4) configurations.The Bi-N_(3)S_(1)/CNSs display a rate capacity of 129.2 mAh g^(-1)even at 10 A g^(-1)and an impressive cyclability characterized by over 5000 cycles at 5 A g^(-1),on account of its optimal coordination environment with more active Bi centers and K^(+)adsorption sites.Notably,assembled potassium-ion full cell Mg-KVO//Bi-N_(3)S_(1)/CNSs also shows an outstanding cycling stability,enduring 3000 cycles at 2 A g^(-1).Therefore,it can be demonstrated that regulating the electronic structure of metallic centre M-N_(4) via changing the type of ligating atom is a feasible strategy for modifying carbon anodes,on the base of co-doping metal and non-metal.
基金supported by Sichuan Science and Technology Program(Nos.2020YFH0176 and 2020SZYZF0002)the Fundamental Research Funds for the Central Universities(No.20826041E4280)the Sichuan International and the Scientific and technological innovation cooperation project(No.2022YFH0039).
文摘Pt single atoms catalysts with precise coordination environment and high stability are expected to achieve high performance of propane dehydrogenation(PDH).In this work,an innovative synthetic strategy is proposed to construct the S-1@0.1Pt9Zn@DPS-1 nanocomposite as a highly efficient PDH catalyst.Defect engineering is applied to induce the formation of defective porous silicalite-1(DPS-1),which is favorable for achieving the uniformly distributed ZnO nanoclusters.The ZnO nanoclusters were further served as anchoring sites to stabilize the isolated Pt atoms.The structural characterization revealed that penta-O coordinated Pt single atom coupled with ZnO nanoclusters decorated on the DPS-1.Moreover,the atomically dispersed Pt atoms with the ideal coordination environment could act as the predominant active sites for PDH process.As expected,the optimal S-1@0.1Pt9Zn@DPS-1 catalyst delivered an excellent PDH performance(propane conversion of 40.7%,propylene selectivity of 97.5%)and good cycling regeneration stability.This work provides a new way for improving the activity and stability of catalysts in the field of industrial catalysts.
基金supported by the National Natural Science Foundation of China(22373017)the“Chuying Program”for the Top Young Talents of Fujian Province.
文摘The electrocatalytic CO_(2) reduction reaction(CO_(2)RR)represents an effective way to address energy crises and environmental issues by converting CO_(2) into valuable chemicals.Single-atom catalysts(SACs)can achieve excellent catalytic activity in CO_(2)RR.However,the study of CO_(2)RR on SACs still poses significant challenges,especially in terms of controlling the selectivity towards the deep product such as CH4 and CH3OH.Herein,we employ density functional theory(DFT)calculations to investigate the CO_(2)RR on Cu SAC supported on N-doped graphene(Cu-N/C)and explore the role of N dopants on the CO_(2)RR performance.Compared to Cu SACs sup-ported on N-doped defective graphene with double vacancy(Cu-N/C-DV),Cu SACs supported on N-doped defective graphene with single vacancy(Cu-N/C-SV)can effectively convert CO_(2) into the deeply reduced C1 products,including CH_(4) and CH_(3)OH,thus further indicating that Cu-N/C-SV has a stronger interaction with*CO,which is conducive to the deep reduction of*CO.Increasing the coordination number of N atoms or the proximity of doping site to the Cu active site can effectively enhance the stability of catalyst and promote the adsorption of*CO on Cu-N/C-SV.However,this also increases the free energy of the formation of*CHO intermediate.The results suggest that CuC3-Nm,which contains a N atom in the second coordination shell(meta-position)of Cu SACs,has the best electrocatalytic performance of CO_(2)RR in terms of both selectivity and catalytic activity,not only contributing to an in-depth understanding of the reaction mechanism of CO_(2)RR on SACs but also providing insights into the design of SACs for efficient CO_(2)RR.
基金the National Key R&D Program of China(Nos.2018YFA0702003 and 2016YFA0202801)the National Natural Science Foundation of China(Nos.51631001,51872030,21890383,21671117,21871159,21901135,51702016,and 51501010)+1 种基金Beijing Institute of Technology Research Fund Program for Young ScholarsBeijing Municipal Science&Technology Commission(No.Z191100007219003).
文摘The local coordination environment of catalysts has been investigated ftor an extended period to obtain enhanced catalytic performance.Especially with the advancement of single-atom catalysts(SACs),research on the coordination environment has been advanced to the atomic level.The surrounding coordination atoms of central metal atoms play important roles in their catalytic activity,selectivity and stability.In recent years,remarkable improvements of the catalytic performance of SACs have been achieved by the tailoring of coordination atoms,coordination numbers and second-or higher-coordination shells,which provided new opportunities for the further development of SACs.In this review,the characterization of coordination environment,tailoring of the local coordination environment,and their related adjustable catalytic performance will be discussed.We hope this review will provide new insights on further research of SACs.
基金supported by the National Key Technology R&D Program of China(No.2020YFA0710202)the National Natural Science Foundation of China(Nos.U1662130,21690080,21690084,and 21721004)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB17020100)。
文摘Fine-tuning of the coordination environment of single-atom catalysts(SACs)is effective to optimize their catalytic performances,yet it remains challenging due to the vulnerability of SACs.Herein,we report a new approach to engineering the coordination environment of M-N-C(M=Fe,Co,and Ni)SACs by using glutamic acid as the N/C source and pyrolysis atmosphere as a regulator.Compared with that in N2,NH3 was able to promote the doping of N at 7<700℃yet etch the N-species at higher temperatures,by which the M-N coordination number(CN)and the electronic structure were delicately tuned.It was found that the electron density of Ni single atoms increased with the decrease of Ni-N CN.As a consequence,the capability of Ni-N-C to dissociate H2 was greatly enhanced and a higher catalytic activity in chemoselective hydrogenation of functionalized nitroarenes was achieved.Moreover,this modulation method could be applied to other transition metals including Fe and Co.In particular,the as-synthesized Co-N-C SAC afforded a turnover frequency of 152.3 h~1 with 99%selectivity to 3-vinylaniline in the hydrogenation of 3-nitrostyrene,which was the highest ever reported thus far and was at least one order of magnitude more active than state-of-the-art noble-metal-free M-N-C catalysts,demonstrating the great potential of engineering the coordination environment of SACs.
基金support from the Ministry of Business,Innovation and Employment for a Catalyst Fund grant(MAUX 1609)the University of Auckland Faculty Research Development Fund,the MacDiarmid Institute for Advanced Materials and Nanotechnology,and a generous Philanthropic donation from Greg and Kathryn Trounson.The authors are also grateful for financial support from the National Key Projects for Fundamental Research and Development of China(2017YFA0206904,2017YFA0206900)+1 种基金the National Natural Science Foundation of China(51825205,51772305,21871279)the Beijing Natural Science Foundation(2191002).
文摘Fe-N-C catalysts represent very promising cathode catalysts for polymer electrolyte fuel cells,owing to their outstanding activity for the oxygen reduction reaction(ORR),especially in alkaline media.In this review,we summarize recent advances in the design and synthesis of Fe-N-C catalysts rich in highly dispersed FeNx active sites.Special emphasis is placed on emerging strategies for tuning the electronic structure of the Fe atoms to enhance the ORR activity,and also maximizing the surface concentration of FeNx sites that are catalytically accessible during ORR.While great progress has been made over the past 5 years in the development of Fe-N-C catalyst for ORR,significant technical obstacles still need to be overcome to enable the large-scale application of Fe-N-C materials as cathode catalysts in real-world fuel cells.
基金We thank the following funding agencies for supporting this work:Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(No.XHT2020-003)the China Postdoctoral Science Foundation(No.2021M692490)the Fundamental Research Funds for the Central Universities(No.WUT:2020Ⅲ029,2020IVA100).
文摘Designing highly efficient bifunctional electrocatalysts for oxygen reduction and evolution reaction(ORR/OER)is extremely important for developing regenerative fuel cells and metal-air batteries.Single-atom catalysts(SACs)have gained considerable attention in recent years because of their maximum atom utilization efficiency and tunable coordination environments.Herein,through density functional theory(DFT)calculations,we systematically explored the ORR/OER performances of nitrogencoordinated transition metal carbon materials(TM-N_(x)-C(TM=Mn,Fe,Co,Ni,Cu,Pd,and Pt;x=3,4))through tailoring the coordination environment.Our results demonstrate that compared to conventional tetra-coordinated(TM-N_(4)-C)catalysts,the asymmetric tri-coordinated(TM-N_(3)-C)catalysts exhibit stronger adsorption capacity of catalytic intermediates.Among them,Ni-N_(3)-C possesses optimal adsorption energy and the lowest overpotential of 0.29 and 0.28 V for ORR and OER,respectively,making it a highly efficient bifunctional catalyst for oxygen catalysis.Furthermore,we find this enhanced effect stems from the additional orbital interaction between newly uncoordinated d-orbitals and p-orbitals of oxygenated species,which is evidently testified via the change of d-band center and integral crystal orbital Hamilton population(ICOHP).This work not only provides a potential bifunctional oxygen catalyst,but also enriches the knowledge of coordination engineering for tailoring the activity of SACs,which may pave the way to design and discover more promising bifunctional electrocatalysts for oxygen catalysis.
基金the key program of National Natural Science Foundation of China(No.51831009)the general program of National Natural Science Foundation of China(No.52071285).
文摘The mechanism governing the pseudocapacitive lithium storage behavior is one of the most critical unsolved issues in conversion-type anodes for lithium-ion batteries.In this work,we,for the first time,demonstrate that the pseudocapacitive capability of iron oxide-based anodes is closely associated with the electronic structures of iron ions.As proof of concept,the introduction of amorphization,nitrogen doping,oxygen vacancies reduces the coordination of iron ions and contributes significantly to the pseudocapacitive lithium storage capability of iron oxide,reaching up to 96%of the specific capacity at 1 mV·s^(−1).Due to the significantly modulated coordination environment,the 3d electrons of Fe(II)are delocalized with increased spin state and the energy band gap is narrowed,accompanied by an upshift of Fermi energy.The redox activity and carrier mobility of iron oxides are substantially increased,which substantially enhance the exchange current density and thereby improve the pseudocapacitive capability of iron oxide.
