Efficient coupling of Ga-doped nickel phosphide and Ni(OH)2 for enhanced hydrogen evolution at high temperature

Transition metal-based hydroxides for hydrogen evolution reaction (HER) are generally limited by inherent poor activity and low electrical conductivity. The rational design of heterostructures to optimize electronic structure has become an effective approach to enhance the catalytic activity. Herein, Ga-doped nickel phosphide was successfully constructed on the surface of Ni(OH)2 by simple electrodeposition and subsequent low-temperature phosphating treatment, harvesting a unique 3D nanoflower-cluster heterostructure (GaNiP/Ni(OH)2). The porous ultrathin nanopetal formed by the interposition of Ga not only combines good conductivity and abundant active sites, but also possesses super-hydrophilicity, which greatly promotes the release of bubbles during HER process and facilitates the exposure of active sites. More importantly, Ni atoms in Ni5P4 are partly replaced by Ga resulting in electron rearrangement, optimizing Had adsorption energy. Therefore, GaNiP/Ni(OH)2 shows the outstanding HER performance, delivering current densities of 10 and 100 mA·cm−2 with just 70 and 141 mV overpotentials (test condition: 60 °C), respectively, accompanied by superior durability (500 h at room temperature and 150 h at 60 °C). This work provides a facile controllable and promising structural coupling method for the synthesis of HER materials with unique structures.