Universal strategy of iron/cobalt-based materials for boosted electrocatalytic activity of water oxidation

Low-dimensional cobalt-based materials have proved to be one of the promising catalytic systems for oxygen-evolution reaction (OER). How to develop a facile and universal strategy for significantly improving their catalytic performance is of great significance, but still faces great challenges. Herein, a series of cobalt-based nanowires (CoS₂, CoP, CoF_2, and Co₃O₄) are synthesized and used as conceptual examples to explore the universality to enhance their OER catalytic activity. The FeOOH-modified cobalt-based electrocatalysts exhibit significantly improved OER catalytic performance compared to the pristine samples. Especially, the optimal CoS₂@FeOOH material delivers the smallest overpotential of 260 mV at 100 mA cm^-2, which outperforms most of the reported excellent materials. Notably, the CoP||CoP@FeOOH electrolyzer (1.63 V@30 mA cm^-2) delivers higher performance than the CoS₂||CoS₂@FeOOH electrolyzer (1.72 V@30 mA cm^-2) benefiting from the better HER catalytic activity of CoP. In addition, the post-characterizations confirm that the real catalytic structure of those electrocatalysts consists of a surface CoOOH@FeOOH catalytic layer and cobalt-based nanowire core. The Co-Fe catalytic layer provides more active centers for the adsorption and dissociation of water molecules as well as the formation of oxygen, while the nanowire core acts as an electron transport channel to realize better reaction kinetics. Our work not only develops a general strategy to enhance the catalytic activity but also provides new ideas for the facile design of other advanced catalytic materials.