Anion-rich Ir-doped CoOx for boosting oxygen evolution reaction in water electrolysis

Abstract

Owing to the sluggish kinetics of oxygen evolution reaction (OER) in electrochemical water electrolysis process, efficient and durable OER electrocatalysts are crucially needed. However, it is a great challenge to improve the comprehensive performance of OER electrocatalysts by utilizing various synergistic methodologies. To solve these issues, herein, Ir-doped Co-based compounds with regulated anions were synthesized using a coprecipitation method as the electrodes for boosting the OERs. Doping with Ir atoms modified the coordination environments and electronic structures of the CoOx-CO32- lattice, and the generated Co3+ species promoted the generation of active species for the OER. It is worthwhile noting that a hybrid crystalline/amorphous IrCoOx-CO32- compound was obtained with an Ir content of 10.09 wt.% and a large amount of Co3+, and demonstrated excellent electrocatalytic OER performance. The overpotential required for the developed IrCoOx-CO32- to achieve 10 mA cm-2 was as low as 207 mV with a very low Tafel slope of 61.7 mV dec-1, which is better than the commercial IrO2. Furthermore, anions created in the IrCoOx significantly promoted the OER, and their effects were decreased in the order of CO32- > PO43- > OH-. This work clarifies the synergistic mechanism of cations and anions on the electrocatalytic OER performance of Co-based compounds, providing new insights for designs of high-performance OER electrocatalysts for water electrolysis.