Surpassing Pt hydrogen production from {200} facet-riched polyhedral Rh2P nanoparticles by one-step synthesis

The efficient water electrolysis catalyst is prominently important and urgent to forward the widespread applications of hydrogen energy. In this work, polyhedral-morphology controlled rhodium phosphide (Rh2P) nanoparticles are synthesized by one-step high temperature pyrolysis under Ar atmosphere at 90 Pa. By analyzing the morphologies of Rh2P, the crystal facets of {200}, {220} and {111} are dominant in the 26-facet polyhedrons, and {200} facets account for 58% of the total surface area of polyhedral 26-facet shapes. The overpotentials of polyhedral Rh2P NPs are 12.6 mV and 10.5 mV at 10 mA m−2 in 0.5 M H2SO4 and 1 M KOH electrolytes, even lower than those of Pt/C. Theoretical calculations indicate that {200} facets of Rh2P NPs have the highest catalytic activity among {200}, {111}, and {220}, with the lowest hydrogen adsorption free energy. The substantial exposure of {200} facets is beneficial to the high catalytic activity of Rh2P NPs. [Display omitted] •One-step pyrolysis is proposed to synthesize polyhedral Rh2P nanoparticles.•A moderate ΔGH-ad and lower water dissociation energy on highly active {200} facets is most favorable for HER.•Only a low operation η10 of 12.6 mV and 10.5 mV is required for HER in 0.5 M H2SO4 and 1 M KOH with good stability.•Highly active {200} facets on polyhedral Rh2P provide the high catalytic activity.