Preparation Of Porous Layered Double Metal Hydroxides And Their Electrocatalytic Oxygen Evolution Performance

Improving the oxygen evolution reaction rate while replacing noble metals with earth abundant materials can be transformative.Layered double metal hydroxides（LDHs）nanosheets can be such a class of materials.However,they agglomerate easily,and their electrocatalytic activity and conductivity are suppressed.Herein,we propose simple co-precipitation and surface etching to prepare ordered macroporous-mesoporous CoNiFe-LDHs with a high-density of defects.The ordered structure avoids the agglomeration of single-layer nanosheets.In a single macropore,there are a large number of mesoporous channels formed by interwoven monolayer nanosheets,which greatly increases the specific surface area of the catalyst.Meanwhile,the high-density of defects on the nanosheet surface generates abundant metal vacancies and oxygen vacancies,distorting the single-layer nanosheets significantly,and altering the electronic properties around the metal（M）M-M bonds and M-O bonds.And enhanced M-M interaction enhances electron transport.The electrons from the Co and Fe are transferred to Ni,thereby accelerating the rate-controlling reaction step of the OOH*formation.This new material shows an extremely low overpotential of 197 m V at a current density of 10 m A cm^-2and a surprising stability of over 70 h in alkaline media.This work aims to design excellent catalytic structures,identify reactive sites,study the unique electronic structures of catalyst surfaces and bulk phases,understand the reaction mechanism,and seek an LDH structure with excellent development potential.