CoFe2O4/β-Ni(OH)2 Heterojunctioned Composite as an Advanced Electrocatalyst for Oxygen Evolution Reaction

초록

Electrochemical water splitting has been regarded as a key element in the transition toward a hydrogen economy. However, the practical application of electrochemical water electrolysis has been limited by the sluggish kinetics of two half-reactions, namely hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Especially, the OER act as a bottleneck in the overall water splitting owing to its high energy barrier originated from the four-electron transfer involved reaction and O-O bond formation. Herein, we rationally designed the cobalt iron spinel-type oxide and β-nickel hydroxide heterojunction composite material (CoFe2O4/β-Ni(OH)2), which was prepared by the one-pot hydrothermal method for the OER. The as-prepared catalyst shows extremely low overpotentials of 278 mV to drive a current density of 10 mA cm?2, the significantly low Tafel slope of 67.5 mV dec?1, and superior mechanical and chemical stability over 30 h OER process in the 1 M KOH alkaline media. These outstanding OER performances are mainly attributed to the synergistic effect of the heterojunction structure of CoFe2O4/β-Ni(OH)2, leading to improving intrinsic catalytic activity, electric conductivity, and durability. This facile fabrication approach of heterojunction composite of CoFe2O4 spinel-type oxide and β-Ni(OH)2 can be extensively applied to other energy conversion and storage systems, such as batteries and fuel cells