Silicon-doped cobal–aluminum layered double hydroxide electrocatalyst with high catalytic activity for oxygen evolution reactions

Abstract

Electrochemical water splitting is a zero-carbon-emission and environmentally friendly method for hydrogen production. However, the process requires electrocatalysts to lower its energy requirements. In this study, Si-doped cobalt–aluminum layered double hydroxide (Si-CoAl-LDH) had been successfully synthesized by SiCl₄ chemical etching at room temperature. The Co-O-Si chemical bonds promoted the formation of γ-CoOOH_x during the process of water oxidation, thereby increasing the number of active sites. Moreover, Theoretical calculations revealed the overlap of atomic orbitals on the Si-CoAl-LDH catalyst surface and the improved electronic structure due to Co–O–Si chemical bonds. The Si-CoAl-LDH exhibited overpotentials of 295, 336, and 363 mV for oxygen evolution reactions (OERs) at current densities 10, 50, and 100 mA cm⁻², respectively. The Tafel slope of the sample was 74.16 mV·dec⁻¹. Physical characterization and in situ Raman analysis revealed the formation of intermediate hydroxylated cobalt species, which act as active centers during OER. This study serves as a basis for the surface reconstruction and activity enhancement of other electrocatalysts through Si doping.