Co-Ni-Mo phosphides hierarchical nanoarrays as bifunctional electrocatalysts for excellent overall water splitting

At present, it is still a critical challenge to simultaneously facilitate the overall water splitting reaction by an electrocatalyst with high activity, good durability, and low cost. Herein, ultrathin nanosheets Co-Mo-Ni heterostructured phosphide bifunctional electrocatalysts were constructed on Cu(OH)2 nanorod arrays toward an efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The electrocatalysts are rationally designed to be composed of heterostructure CoMoP, MoNiP, and Cu3P. The formation of M−P bonds can capture intermediates, avoid deactivation, and induce ligand effects to enhance catalytic performance. Therefore, the synergistic effect of heterogeneous structure and phosphorylation is the main contribution to promoting HER and OER. As a result, the bifunctional electrocatalysts exhibit highly efficient with HER overpotentials of 106 mV and 160 mV at current densities of 100 and 200 mA cm−2, and OER overpotentials of 243 mV and 280 mV, respectively. The constructed overall water-splitting cell realized a low potential of 1.65 V with a current density of 100 mA cm−2 and long-term stability, which is comparable to the reported bifunctional catalysts.