Cuprous sulfide derived CuO nanowires as effective electrocatalyst for oxygen evolution

Abstract Synthesizing low-cost and efficient materials to catalyze oxygen evolution reaction (OER) is urgently needed but remains challenging so far. In this study, Cu2S nanoparticles were prepared on Cu foam, forming a high-efficiency Cu2S/Cu foam robust pre-electrocatalysts. The Cu2S/Cu foam, as a new precatalyst for OER, presents an excellent efficiency with 373 mV of overpotential for 50 mA cm−2, which is superior to RuO2 (400 mV). The Cu2S/Cu foam pre-electrocatalyst also demonstrates an impressive durability with a current retention of 86% after catalyzing OER for 60 h with a current density 60 mA cm−2. Moreover, the structure, morphology and phase transformation of the pre-electrocatalyst during the OER operation were revealed. It was found that the Cu2S nanoparticles will evolve into sulfate ions embedded CuO nanowires that catalyze oxygen evolution reaction. It is believed that the evolution of Cu2S nanoparticles to sulfate ions embedded CuO involve the oxidation reaction under the high overpotential and the disproportionate reaction of Cu(I) species. The result suggests that hybridized cuprous sulfide/copper materials are attractive noble-metal-free pre-catalysts for water splitting. Our study may offer a new way to develop metal sulfide catalysts for high-performance water oxidation reaction.