Metal-organic framework-derived CoP2@ N-doped carbon hollow spheres for efficient oxygen evolution reaction

1.Introduction Hydrogen is considered as a viable alternative to fossil fuels[1,2].Large-scale hydrogen production by electrochemical water splitting is regarded as an important approach.It consists of two half-reactions:hydrogen evolution reaction(HER)at the cathode and oxygen evolution reaction(OER)at the anode[3].Compared to the HER,the OER has sluggish kinetic and large overpotentials,re-sulting from the complex oxidation pathway[4,5].Although RuO2 and IrO2 have excellent catalytic OER performance[6],their large-scale deployment is unfeasible due to the scarcity and high cost of these noble metal elements.Thus,cheap OER electrocatalysts have been actively investigated[7].