Self-assembled heterojunction CoSe2@CoO catalysts for efficient seawater electrolysis

The exploration of efficient, stable, and inexpensive oxygen evolution reaction (OER) catalysts is of great importance for the practical application of seawater electrolysis. In this work, CoSe2@CoO/CF catalysts are prepared by a simple and scalable one-step electrodeposition method, and the OER performance of the catalysts is investigated in depth. The CoSe2@CoO/CF catalyst (273 mV) shows significantly better activity than the IrO2 catalyst (435 mV). The catalyst can be steadily operated at high current densities (100 mA cm−2) for over 200 h in the 1.0 M KOH + seawater. Notably, the catalyst exhibits excellent selectivity with a Faraday efficiency of approximately 98% for OER, while the ClO− concentration is only 1.312×10−7 mol L−1 as measured by UV-visible characterization. Strong overlap between the Co 2p orbitals of monometallic bi-compound catalysts facilitates the rate of para-site electron transfer. In addition, the impressive performance is attributed to the urchin-like heterogeneous structure with abundant active centers.