Peony-like CuxSy hybrid iron-nickel sulfide heterogeneous catalyst for boosting alkaline oxygen evolution reaction

Designing and fabricating earth-abundant and highly-efficient electrocatalysts is vital to accelerate dynamics of the oxygen evolution reaction (OER), which is a half reaction of water splitting. In the present work, we developed and successfully synthesized copper sulfides with diverse valence states hybridizing iron-nickel sulfide (CuxSy/FeNiS) heterogeneous catalyst via a governable two-step hydrothermal method, which processes superior OER performance and outstanding durableness in 1.0 M KOH solution. Benefitting from the polyvalent copper dopant and competent interfacial effects between Cu sulfides and FeNiS, this self-supported hybrid material requires 286 and 354 mV to achieve 50 and 500 mA cm-2, respectively. Besides, the plentiful disordered structures in CuxSy/FeNiS hybridization also enrich the exposure sites and modulate the electronic interaction of active sites and enhance the intrinsic OER activity. Furthermore, this optimal CuxSy/FeNiS electrode exhibits remarkable stability at both 10 and 100 mA cm-2 prolonged chronopotentiometry process.