CoFe layered double hydroxides with adjustable composition and structure for enhanced oxygen evolution reaction

Abstract

Layered double hydroxides (LDHs) are promising catalysts for water electrolysis. Many efficient LDHs have been produced by adjusting their composition and structure. Herein, by using only sodium carbonate as a precipitator, we prepared gram-scale CoFe LDHs rich in carbonate anions depending on the incomplete double hydrolysis between carbonate and metal ions under atmospheric pressure. Owing to the flexible iron valence state, the coordination environment, and electronic structure of cobalt and iron in CoFe LDHs can be modified. The catalytic performance was substantially improved for the oxygen evolution reaction (OER) owing to the exposure of more metal active sites and the increase in the charge transfer rate. By adjusting the molar ratios of Co and Fe, Co₁Fe₁ LDH with excellent OER performance, which reached 10 mA cm⁻² at an extremely low overpotential (270 mV) and a very low Tafel slope (42.7 mV dec⁻¹), was obtained. Our work can pave the way for low cost high-performance LDHs in water electrolysis.