Hierarchical CoMoS4 flakes with rich physico-electrochemical physiognomies for electrocatalytic oxygen evolution reaction

Abstract

To develop ultraefficient electrocatalysts for application in oxygen electrochemistry based energy conversion and storage devices, herein, an extremely facile synthesis procedure has been innovated to synthesize hierarchical CoMoS₄ flakes with nanocrystallinity and ample intrasheet porosity with wettable surface, and the material has been used as a prospective electrocatalyst for oxygen evolution reaction (OER) in alkaline medium. The electrochemical analysis reveals that CoMoS₄ electrocatalyzes OER at a low overpotential. Further, it is ascertained that the electrocatalytic OER by CoMoS₄ occurs with a very low value of Tafel slope and high turnover frequency. In addition, CoMoS₄ shows excellent current retention and constant potential requirement during electrocatalytic OER for long duration and low charge transfer resistance during the electrochemical reactions. The small crystallites and model microstructural physiognomies of flake-like CoMoS₄ offer supreme accessibility to the integrated catalytic sites and lowly-restricted diffusibility of the electroactive ions for improved overall kinetics of the electrocatalytic OER. The small crystallites in flake-like CoMoS₄ also offer more electroactive surface, which leads to rich turnover frequency and improved kinetics during electrocatalytic OER. In addition, the flake-like microstructure of CoMoS₄ possess ample intersheet porosity, which provides microstructural sturdiness during ion intercalation/de-intercalation and facilitates the easy escape of the gaseous oxygen produced during electrocatalytic OER for a very long duration. The study demonstrates the chemical and microstructural design of non-noble multimetal sulfides for the future development of highly efficient OER electrocatalysts, which will boost the advancement of ultraefficient energy conversion and storage systems based on oxygen electrochemistry.