Self‐Supported Mesoporous Iron Phosphide with High Active‐Site Density for Electrocatalytic Hydrogen Evolution in Acidic and Alkaline Media

Abstract Developing low‐cost and highly active electrocatalysts for the hydrogen evolution reaction (HER) is urgently desired. We fabricated a mesoporous FeP self‐supported electrode (meso‐FeP/CC) through a facile and mild sol‐gel method. The mesoporous FeP self‐supported electrode displays superior HER electrocatalytic activity, requiring low overpotentials of 57 and 84 mV to drive 10 mA cm −2 in acidic and alkaline electrolyte, respectively. Meanwhile, the as‐prepared electrode exhibits fast kinetics with a small Tafel slope (acidic media: 42 mV dec −1 and alkaline media: 60 mV dec −1 ). The excellent catalytic performance of the electrode benefits from mesoporous framework with a large surface area (74.1 m 2 g −1 ) and highly conductive self‐supported structure. The former endows the catalyst with a large active‐site density (3.5×10 18 site per mg) and substantial accessible mesopores, and the latter accelerates reaction kinetics. This work offers a new avenue for rational designing high‐efficiency FeP HER electrocatalysts.