A Monodisperse Rh2P‐Based Electrocatalyst for Highly Efficient and pH‐Universal Hydrogen Evolution Reaction

The search for Pt‐free electrocatalysts exceeding pH‐universal hydrogen evolution reaction (HER) activities when compared to the state‐of‐the‐art commercial Pt/C is highly desirable for the development of renewable energy conversion systems but still remains a huge challenge. Here a colloidal synthesis of monodisperse Rh₂P nanoparticles with an average size of 2.8 nm and their superior catalytic activities for pH‐universal HER are reported. Significantly, the Rh₂P catalyst displays remarkable HER performance with overpotentials of 14, 30, and 38 mV to achieve 10 mA cm^?2 in 0.5 m H₂SO₄, 1.0 m KOH, and 1.0 m phosphate‐buffered saline, respectively, exceeding almost all the documented electrocatalysts, including the commercial 20 wt% Pt/C. Density functional theory calculations reveal that the introduction of P into Rh can weaken the H adsorption strength of Rh₂P to nearly zero, beneficial for boosting HER performance.