Electrochemical Hydrogen Evolution Reaction Efficiently Catalyzed by Ru2P Nanoparticles

Abstract Developing alternatives to Pt catalysts is a prerequisite to cost‐effectively produce hydrogen. Herein, we demonstrate Ru 2 P nanoparticles (without any doping and modifications) as a highly efficient Pt‐like catalyst for the hydrogen evolution reaction (HER) in different pH electrolytes. On transferring the hexagonal close‐packed crystal structure of Ru to the orthorhombic structure of Ru 2 P, a greatly improved catalytic activity and stability toward HER is found owing to Ru−P coordination. The electronic state change originates from the P−Ru bonding structures, which accounts for the HER activity improvement compared with Ru nanoparticles. Specifically, Ru 2 P nanoparticles can drive 10 mA cm −2 at a very low overpotential of 55 mV, only 8 mV more than Pt/C in an acidic solution; and an extremely low overpotential of approximately 50 mV is needed in alkaline solution, about 20 mV less than the Pt/C catalyst. The Volmer–Tafel mechanism is indicated on Ru 2 P nanoparticles with the typical Tafel slope of 30 mV dec −1 of Pt metal indicating a Pt‐like catalytic ability. Ru 2 P is more active in the Ru‐P family as H atoms prefer to adsorb on Ru atoms rather than on the P element according to theoretical calculations. Considering the low price of Ru (20 % of Pt), anti‐corrosion ability in the electrolyte, and the safe and reliable fabrication approach, the powder Ru 2 P nanoparticles make an excellent HER catalyst with great promise for large‐scale water electrolysis applications.