Urchin-Like Cobalt-Copper (Hydr)oxides as an Efficient Water Oxidation Electrocatalyst

The development of efficient and low-cost oxygen evolution reaction (OER) catalysts is essential for the generation of clean hydrogen energy from water splitting. Herein, a novel hierarchical urchin-like cobalt-copper (hydr)oxide in situ grown on copper foam (CoCuO_x H_y (S)/CF) was synthesized through the electrochemical transformation of cobalt-copper sulfides (Co₉ S₈ -Cu_1.81 S) via anodization process. This CoCuO_x H_y (S)/CF anode exhibited a low overpotential (η) of 274 mV at a current density of 100 mA cm^-2 with a robust durability over a period of 40 h when operated at 10 mA cm^-2 . Further investigations imply that the unique nanowires aggregated urchin-like structure of CoCuO_x H_y (S) derived from the in situ anion exchange process could facilitate the exposure of active sites and accelerate electron transfer. More importantly, the incorporation of copper resulted in an electronic delocalization around the cobalt species, which contributed to reach a high-valent catalytically active cobalt species and further improved the OER performance.