One-step synthesis of mesoporous Cobalt sulfides (CoSx) on the metal substrate as an efficient bifunctional electrode for overall water splitting

TL;DR

This paper presents a rapid, one-step anodization method to synthesize mesoporous cobalt sulfides on metal substrates, resulting in an efficient bifunctional catalyst for water splitting with excellent electrochemical performance.

Contribution

A simple, fast, and cost-effective one-step anodization process for in-situ growth of mesoporous CoSx catalysts on metal substrates for water splitting.

Findings

Achieved low overpotentials for HER and OER (102 mV and 284 mV at 10 mA/cm²)

Demonstrated a cell voltage of 1.64 V for overall water splitting

Produced mesoporous CoSx with high catalytic activity in alkaline solution

Abstract

Electrocatalysts based on transition metal sulfides are drawing accelerating concerns in renewable energy research because of their intrinsically excellent activities towards both hydrogen evolution reaction and oxygen evolution reaction. To date, considerable efforts are made to improve the performance of these catalysts, but ignoring the improper synthesis strategy would incur additional cost to the catalyst. Herein, a convenient, one-step anodization method is developed for fast construction of cobalt sulfides. Without any high-temperature or long-time treatment, mesoporous CoSx is self-grown on the metal substrate in minutes. As a result, as-anodic CoSx requires overpotentials of 102 mV for HER and 284 mV for OER to achieve a current density of 10 mA m-2 in alkaline solution. Moreover, the tandem bifunctional as-anodic CoSx exhibits a required cell voltage of 1.64 V for overall water splitting in alkaline solution, exceeding most of the documented Co-based electrocatalysts.