Compartmentalized Structure Reconstruction in Metal-Organic Frameworks (MOFs) for Efficient Oxygen Evolution Reaction

Abstract

Structure evolution of hydroxide or oxyhydroxides is key to efficient oxygen evolution reaction (OER), but the controllable regulation of such structure reconstruction remains challenging. Herein, we report that simultaneously encapsulating Ni 2+ -O-Fe 3+ units and conductive Ni@C species inside the mesopores of metal-organic frameworks (MOFs) can effectively promote the structure reconstruction toward efficient OER. Multivariate MOFs Ni-BA is constructed by mixing two ligands with distinguished thermal stability. After careful thermal treatment, the thermal labile ligand is selectively carbonized to create mesopores with confined Ni@C and coordinated unsaturated Ni sites (defect sites) in the inner walls. Further adsorption of Fe 3+ at the defect sites leads to formation of Ni 2+ -O-Fe 3+ units inside the pores. The synergistic compartmentalization of Ni 2+ -O-Fe 3+ units and conductive Ni@C species inside the nano-space creates bi-functional nano-reactors to promote the structure evolution of active NiOOH and accelerate multielectron transfer. As a result, the optimized catalyst delivers an excellent OER performance with small overpotentials of 227 mV and 310 mV at current densities of 10 mA cm -2 and 100 mA cm -2 , respectively, outperforming most of the MOFs-based OER electrocatalysts.