Metal organic framework-derived transition metal-doped CoSx nanocage for enhanced visible light-assisted methanol electrocatalytic oxidation

Abstract

Designing noble metal-free anode catalysts for visible light-assisted direct methanol fuel cells still remains a significant challenge. In this study, combining the photocatalytic and electrocatalytic properties of CoS_x, a visible light-assisted methanol electrocatalytic oxidation strategy was provided. Doping engineering was employed to adjust the electronic structure of CoS_x and improve their photoassisted methanol electrocatalytic oxidation activity. Using ZIF-67 as precursor, transition metal-doped CoS_x (M-CoS_x, M = Zn, Cu, Ni, and Cd) nanocage was synthesized by cation exchange and L-cysteine-controlled etching. Cd doping not only widens the light adsorption to the visible region but also enhances the separation efficiency of photogenerated electron–hole pairs. The electrochemical and photochemical results indicated that the strong oxidative photogenerated hole, OH˙, and O₂˙⁻ are beneficial for methanol electrocatalytic oxidation. The synergistic electrocatalytic and photocatalytic effect will be a practical strategy for improving the methanol electrocatalytic oxidation activity of noble metal-free semiconductor catalysts.