Amorphous high-entropy IrRuCrFeCoNiOx as efficient water splitting oxygen evolution reaction electrocatalysts

Abstract

The process of oxygen evolution reaction (OER) for water splitting is intricate and demands a substantial amount of energy. It necessitates the utilization of catalysts that are both highly efficient and durable in order to overcome the slow reaction kinetics. Amorphous, high-entropy oxide nanoparticles were prepared using simple one-step coprecipitation in this work. Due to highly disordered atomic arrangement in the amorphous structure of these catalysts and their high specific surface area, they compete to form active sites in the OER. Among them, IrRuCrFeCoNiOx demonstrated the optimal OER catalytic activity, requiring just a low overpotential (190 mV) with minimal Tafel slope (51.1 mV dec−1) to achieve the current density of 10 mA cm−2 in 1 M KOH. Through surface self-reconstruction in the OER, a crystalline active layer with a thickness of several nanometers formed on the catalyst’s surface. The stable core-shell nanoarchitectures composed of crystalline and amorphous regions substantially improved the stability of the catalyst. This work verified the effectiveness of high-entropy design and the significant improvement of noble metal doping on OER performance. It develops a new OER catalyst for water splitting with great activity and stability.