Defect-rich CoFeCu alloy nanoflowers for efficient oxygen evolution reaction in alkaline media

Energy shortages and environmental problems caused by the intensive use of fossil fuels have led to an urgent search for alternative energy sources. The solar-powered hydrogen generation from water splitting is expected to replace the traditional fossil fuels extraction. However, the slow anodic oxygen evolution reaction (OER) of the water splitting limits the overall efficiency of hydrogen production. The introduction of foreign atoms into bimetallic alloys is an effective strategy for constructing rich defects, modulating the electronic structure and optimizing the electrocatalytic performance. In this study, CoFeCu alloy nanoflowers (CoFeCu/NF) are prepared as electrocatalysts for OER by introducing Cu into the CoFe alloy through a facile electrodeposition method. It is revealed that the introduction of Cu not only enhances the electronic interactions between the elements, i.e., Co, Fe, and Cu, but also induces the generation of a large number of Fe3+ cationic vacancies which facilitate the surface reconstruction of Fe into FeOOH species during OER. Benefiting from the synergistic effect of CoOOH and FeOOH generated by in-situ electrochemical reconstruction, CoFeCu/NF exhibits satisfactory OER catalytic performance in 1.0 M KOH (η10 mA cm−2 = 257 mV) and is able to maintain a good stability for 48 h at 50 mA cm−2. Our work demonstrates the roles of introducing Cu into transition metal-based alloys and provides an effective strategy for the rational design of OER electrocatalysts in alkaline media.