Accelerating Kinetics of Oxygen Evolution Reaction Via Expanding Interlayer Spacing of 1d Core-Shell Layered Double Hydroxides

Abstract

Layered double hydroxides (LDH) have been recognized as promising electrocatalysts for OER. However, the poor electron conductivity and limited interlayer spacing that relates with the ion diffusion decrease reaction kinetics of OER. In this work, acetate anion was selected to construct basic cobalt acetate (COAC) on the surface of CoNi-LDH via a facile ethanol bath reaction. The similar lamellar structure between COAC and CoNi-LDH promise the successful growth of COAC on CoNi-LDH. TEM indicates that the interlayer spacing of COAC is around 1.5 times larger than that of CoNi-LDH, efficiently accelerates the kinetics of OER due to the accelerated ion diffusion. In addition, the substitution of OH with acetate ions changes the electron distribution of Co-O octahedron in hydroxides sheets, which was evidenced to raising the density of Co3+ in the electrocatalysts, facilitating the formation of CoOOH and promoting the intrinsic activity of CoNi-LDH@COAC/NF.  As a result, the overpotential of CoNi-LDH@COAC/NF (253 mV) is 45 mV and 47 mV lower than that of COAC and CoNi-LDH/NF at the current density of 10 mA cm-2, respectively. This work unravels the enhanced catalytic mechanism of acetate anion in modulating the catalytic performance of LDH, which replenish the application of basic cobalt salt.

Keywords: oxygen evolution reaction, Layered double hydroxide, basic cobalt acetate, Core-shell structure, interlayer space regulation