Mesoporous Mn-Doped FeP: Facile Synthesis and Enhanced Electrocatalytic Activity for Hydrogen Evolution in a Wide pH Range

Water electrolysis is a clean and effective strategy for mass production of hydrogen. Iron phosphide is a fascinating candidate for hydrogen evolution reaction (HER) among the reported Pt-free metal catalysts; however, the catalytic activity of FeP is far behind Pt. Herein, we prepared a highly efficient and durable mesoporous Mn-doped FeP (Mn-FeP) catalyst for HER via a facile and controllable synthesis route. It is manifested that Mn doping leads to improved electroactivity of mesoporous FeP in a wide pH range. For the mesoporous Mn-FeP catalyst, the overpotential is 69, 157, and 173 mV in H2SO4, PBS, and KOH electrolytes at 10 mA cm–2, respectively, which is 21, 40, and 54 mV less than that of its counterpart mesoporous FeP. Furthermore, it can be concluded that the enhanced HER activity of Mn-FeP is ascribed to both the appropriate thermoneutral hydrogen adsorption free energy and the accessible active sites thanks to the mesoporous structure from the density functional theory (DFT) calculation and the experimental results. Our results prove that heteroatom doping is an effective strategy to tune the electron structure of transition metal phosphides (TMPs), and it provides a new avenue to promote the HER activity of TMPs.