Structurally Engineered Hyperbranched NiCoP Arrays with Superior Electrocatalytic Activities toward Highly Efficient Overall Water Splitting

Developing inexpensive transition-metal-based nanomaterials with high electrocatalytic activity is of significant necessity for electrochemical water splitting. In this study, we propose a controllable structural engineering strategy of constructing a hyperbranched architecture for highly efficient hydrogen evolution reaction/oxygen evolution reaction (HER/OER). Hyperbranched NiCoP architecture organized by hierarchical nanorod-on-nanosheet arrays is rationally prepared as a demonstration via a facile solvothermal and phosphorization approach. A strong synergistic benefit from the multiscale building blocks is achieved to enable outstanding electrocatalytic properties in an alkaline electrolyzer, including low HER and OER overpotentials of 71 and 268 mV at 10 mA cm^-2, respectively, which significantly outperforms the counterparts of individual nanorods and nanosheets. The bifunctional catalysts also show highly efficient and durable overall water electrocatalysis with a small voltage of 1.57 V to drive a current density of 10 mA cm^-2. The present study will open a new window to engineering hyperbranched architectures with exceptional electrocatalytic activities toward overall water splitting.