Rational design of Cu–Co thiospinel ternary sheet arrays for highly efficient electrocatalytic water splitting

Abstract

The exploration of highly efficient and scalable potential electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is essential in the field of sustainable energy systems. In this paper, we report the successful synthesis of CuCo₂S₄ ternary sheet arrays (CuCo₂S₄ TSAs) via a simple rational one-pot solvothermal procedure. The CuCo₂S₄ TSA was transformed from CuCo-dihydroxide and uniformly distributed on the microfibre of carbon felt, which effectively enhanced the charge transfer rate. Benefiting from the uniform freestanding sheet structure, the coordination effect of the metal species and the high-conductive carbon skeleton, the ternary composite exhibits excellent OER and HER activity, with the lowest overpotentials of 210 and 69 mV and Tafel slopes of 43.8 and 55.4 mV dec⁻¹, respectively, outperforming the other ternary composites of FeS₂/CoFe₂O₄ and CuS/CuFeS₂, mono-metal sulfides and commercial RuO₂ and Pt/C. Besides, the CuCo₂S₄ TSAs exhibit superior long-term stability relative to noble metal catalysts. Moreover, the excellent overall water-splitting performance was obtained by using CuCo₂S₄ TSA as a catalyst, providing an effective low-cost and large-scale synthetic strategy for high-efficiency binder-free catalysts in renewable energy conversion.