Research progress on electronic and active site engineering of cobalt‐based electrocatalysts for oxygen evolution reaction

Electrocatalytic water splitting has been identified as a potential candidate for producing clean hydrogen energy with zero carbon emission.However,the sluggish kinetics of oxygen evolution reaction on the anode side of the watersplitting device significantly hinders its practical applications.Generally,the efficiency of oxygen evolution processes depends greatly on the availability of cost‐effective catalysts with high activity and selectivity.In recent years,extensive theoretical and experimental studies have demonstrated that cobalt(Co)‐based nanomaterials,especially low‐dimensional Co‐based nanomaterials with a huge specific surface area and abundant unsaturated active sites,have emerged as versatile electrocatalysts for oxygen evolution reactions,and thus,great progress has been made in the rational design and synthesis of Co‐based nanomaterials for electrocatalytic oxygen evolution reactions.Considering the remarkable progress in this area,in this timely review,we highlight the most recent developments in Co‐based nanomaterials relating to their dimensional control,defect regulation(conductivity),electronic structure regulation,and so forth.Furthermore,a brief conclusion about recent progress achieved in oxygen evolution on Co‐based nanomaterials,as well as an outlook on future research challenges,is given.

Defect engineered 2D mesoporous Mo-Co-O nanosheets with crystalline-amorphous composite structure for efficient oxygen evolution

Two-dimensional(2D)mesoporous metal-oxide(hydroxide)nanomaterials with defects are promising towards the realization of efficient electrocatalysis.Herein,we report a facile and effective one-pot solvothermal route to synthesize mesoporous Mo_(x)-Co-O hybrid nanosheets(NSs)which is composed of crystalline Mo_(4)O_(11) and amorphous cobalt hydroxide.Due to the corrosion of 1-octylamine at high temperatures,abundant mesoporous holes are created in situ over the Mo_(x)-Co-O hybrid NSs during the solvothermal process,which is beneficial to increasing the electrochemical surface area.The dimension of the Mox-Co-O NSs,size of mesoporous and the concentration of defects can be easily modulated by controlling the molar ratio of Mo/Co.Electrochemical measurements reveal that the 2D mesoporous Mo_(x)-Co-O NSs show an excellent activity for the oxygen evolution reaction with the highest catalytic activity of η_(10)=276 mV at 10 mA cm^(−2)in 1 mol L^(−1)KOH.Enhanced adsorption of intermediates and abundant oxygen vacancies achieved by appropriate Mo doping are the two main factors that contribute to the excellent catalytic activity of Mo_(0.2)-Co-O NSs.This work,with the construction of 2D metal-oxide(hydroxide)crystallineamorphous nanomaterials possessing abundant holes,oxygen vacancies and enhanced adsorption of intermediates,provides important insight on the design of more efficient catalysts.