Abstract: With the increasing environmental pollution and the depletion of non-renewable resources, it is very important for developing clean and renewable energy. The technology of water-splitting is an efficient and pollution-free method for producing hydrogen and oxygen, which is via two processes of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, the commercial precious metal catalyst has expensive cost and low abundance on earth. Therefore, it is very meaningful for developing the non-noble metal electrocatalysts with lower prices, high activity and stable performance. In this study, a series of nanoflower bifunctional electrocatalysts (CuSe₂-CoSe₂(1∶1)NF, CuSe₂-CoSe₂(3∶1)NF and CuSe₂-CoSe₂(1∶3)NF) were successfully prepared by hydrothermal method. The structure, morphology, elemental composition and valence state of CuSe₂-CoSe₂NF catalyst were analyzed by a series of characterizations. The result shows that the existence of synergistic between CoSe₂ and CuSe₂ in CuSe₂-CoSe₂NF bimetallic selenide catalyst can accelerate the electron transfer and enhance the water-splitting performance. In addition, the CuSe₂-CoSe₂NF catalyst with nanoflower structure has large specific surface area (808 m²/g), which can expose more active sites and further increase the electrochemical performance. Consequently, the CuSe₂-CoSe₂(1∶1)NF catalyst needs 42 and 204 mV overpotentials for HER and OER at 10 mA·cm^-2 current density in 1 mol/L KOH electrolyte. The stability could maintain 100 h. The CuSe₂-CoSe₂(1∶1)NF performance is close to that of commercial Pt/C and RuO₂.

Key words: selenide, hydrogen evolution by electrolysis of water, oxygen evolution by electrolysis of water, bifunctional catalyst, nanoflower, dual active site