High-precision regulation synthesis of Fe-doped Co2P nanorod bundles as efficient electrocatalysts for hydrogen evolution in all-pH range and seawater

The hydrogen evolution reaction (HER) via water electrolysis has gained immense research attention. Seawater electrolysis provides great opportunities for sustainable energy production, but is extremely challenging. Transition metal phosphides are promising candidate electrocatalysts. Herein, we prepared a novel Fe–Co2P bundle of nanorods (BNRs) for catalyzing the HER in seawater electrolysis and over the entire pH range. Cobalt phosphides with different crystal phases and morphologies were obtained by varying the Fe doping amount. The Co:Fe molar ratio of 1:0.5 was found to be optimum. The Fe doping improved the HER performance of Co2P over the entire pH range by providing favorable electronic properties and morphology, lattice distortion, and special coordination environment. The Fe-Co2P BNRs showed higher catalytic activity than 20% Pt/C in seawater at high potentials. The density functional theory calculations revealed that the Fe doping reduced the hydrogen binding strength of Co2P to efficiently accelerate the HER kinetics and produce a favorable charge density. This study provides valuable insights into the design and development of high-efficiency HER catalysts for large-scale seawater electrolysis.