First-principles Study Of Surface Electrocatalytic Reactions Mediated By 3d Transition Metal Atoms

Electrocatalytic reaction is an important research field as an important catalytic mode,which is closely related to material science,physical chemistry.It is strategically significant to explore efficient catalyst for carbon dioxide reduction reaction（CO₂RR）and methanol oxidation reaction（MOR）in energy conversion and storage field.Besides,the first principles calculation based on density functional theory（DFT）is an effective method to explore new materials due to the advantage of not being limited by harsh laboratory conditions and short test period.Among them,single atom catalyst（SAC）and single atom alloy（SAA）catalyst have excellent performance in electrocatalytic reaction due to the characteristics of high atomic utilization rate and high selectivity,indicating the great potential as high effective catalysts.By regulating the supported single atom,the catalyst with excellent performance can be found,which can provide reference for the study of reaction mechanism.In this paper,based on the first principles calculation,the trends of the activity with different 3d transition metal elements on different surfaces of Cu-based SAA in CO₂RR were studied.And the trend of the activity by doping different3d transition metal atoms in graphene surface monatomic catalyst anchored by four nitrogen atoms（M@N₄C,M=3d transition metal atom）in MOR was also studied.Co@N₄C and Zn@Cu（111）were selected as potential electrocatalytic reaction catalysts,which can provide theoretical guidance for the experiment.The main research contents are as follows:（1）Based on the DFT calculation system,the trend of free energy of CO₂RR to formic acid on Cu-based SAA was studied by regulating the 3d transition metal single atom and different surfaces of Cu metal.The competitive reactions including CO and H₂formation were also taken into account.The effect of 3d metal atom doping on the catalytic activity of Cu metal was analyzed from the perspective of intermediate adsorption energy and d-band center.The descriptors were extracted to guide the rational design of high effective CO₂RR catalyst.It is worth mentioning that Zn@Cu（111）has a lower energy barrier than hydrogen evolution reaction and CO generation from CO₂RR,which shows its application potential as an efficient electrocatalyst for CO₂RR generation of HCOOH.（2）The catalytic potential of M@N₄C for MOR was systematically studied.Gibbs free energy,limit potential,d-band center,Bader charge and projected density of states were calculated by DFT.Co@N₄C is a potentially efficient MOR catalyst with low limiting potential of 0.41V.The scale relationship between the d-band center of the key intermediate and the Gibbs free energy is also established.The one-dimensional volcano diagram and the two-dimensional volcano diagram were constructed,showing that the system with the d-band center of-1～1 eV,ΔG_*CH3OH≈-0.25 eV andΔG_*CO≈-0.25eV is the best SAC.This work provides a strategy for improving the activity of MOR and can be extended to other multi-electron electrocatalytic reactions.