Shape effects of nickel phosphide nanocrystals on hydrogen evolution reaction

The preparation of size- and shape-controlled nanoparticles has enabled the understanding of important nanoscale catalytic phenomena, resulting in the design of advanced catalysts with enhanced activities and selectivities. Metal phosphides have recently emerged as a promising class of non-precious metal catalysts for hydrogen evolution reaction (HER), which is a cornerstone in clean and environmentally benign hydrogen production. Although significant progress has been made in metal phosphide catalysts, the impact of the metal phosphide shape has not yet been explored. Herein, we investigated the shape-dependent electrocatalytic activity of nickel phosphide nanoparticles (Ni2P NPs) for the HER. Spherical Ni2P NPs mainly composed of the Ni2P(001) surface showed higher HER activity than rod-shaped Ni2P NPs with the Ni2P(210) surface in terms of overpotential, Tafel slope, and turnover frequency. The results imply that the Ni2P(001) surface would have preferential interactions with the adsorbent and a lower activation barrier for hydrogen adsorption, promoting the overall rate of HER. This study highlights the importance of morphology control in electrocatalysts to boost catalytic performances.