Theoretical Study Of The Electrocatalytic Oxygen Evolution Reaction On C₂N Supported Single Metal Atoms

Oxygen separation reaction（OER）is a half-reaction in the electrolysis of water,which is the bottleneck for efficient electrolytic hydrogen production from water due to the slow kinetic process.The high cost of conventional OER precious metal-based catalysts（IrO₂ and RuO₂）limits their large-scale application.The development of stable,efficient and low-cost OER electrocatalysis is of great importance for the wide application of electrolytic water.In this thesis,based on density functional theory（DFT）calculations,the OER mechanisms on g-C₂N supported single transition metal atoms（TM@C₂N）are intensively investigated.The main research works are as follows:Based on density functional theory（DFT）calculations,the stability of OER catalytic activity of 27 types of single transition metal atoms（TM=Sc-Zn、Y-Cd、La、Ta、W、Os、Ir、Pt、Au）supported by C₂N（TM@C₂N）were intensively investigated.Without considering the co-adsorption of intermediate,Rh@C₂N was screened out as the most effective single atom catalyst（SAC）with an OER overpotential（ηOER）of 0.42 V.In turn,the stabilities of co-adsorption of possible intermediates（*OH,*O）on the SACs were evaluated under the reaction conditions and the OER mechanisms were further investigated with the dynamic adsorption of intermediates.It was suggested that the co-adsorption of intermediates significantly modulate the OER activity of SACs and lower OER overpotentials were obtained on Ir（Ru,Ni,Fe）@C₂N.The overpotential of OER on Rh@C₂N was predicted as 0.33 V.This work suggests that the coadsorption of intermediates on SACs under the reaction conditions needs to be considered to design SACs for OER reactions.Further,it is found that the different co-adsorption configuration can also change the OER activity.For example,the overpotential of OER of 0.17 V was achieved on Rh@C₂N with a meta-stable planar coordination configuration of 2O-TM@C₂N,which inspire us to control the configuration of the intermediates and improve the OER activity.To stabilize the planar coordination configurations,two strategies were prosed:（1）utilizing the strong bonding between B and O by B doping and（2）blocking the active site with another two dimensional materials such as g-C₂N.It is found that with the doping of B,the overpotential of OER was predicted as 0.19 V on Rh@B-C₂N.Also,the presence of second g-C₂N layer can also stabilize the planar configuration and reduce the overpotential of OER.These works provide theoretical understandings for the rational design of OER catalytic materials.