Rh₂P Nanoparticles Partially Embedded in N/P-Doped Carbon Scaffold at Ultralow Metal Loading for High Current Density Water Electrolysis

Precious metal phosphides have attracted considerable research interest for electrocatalysis in recent years, but it remains an open question how to design such electrocatalysts to facilitate the gas-evolving water electrolysis with high activity and durability at low metal loading. In this work, rhodium phosphide nanoparticles are attached on a nitrogen/phosphorus-doped carbon cloth matrix (Rh₂P-N/P-CC) with an ultralow Rh loading of 39.2 μg cm^–2 to be used as an excellent bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). By rationally integrating the merits of its two components, as-reported Rh₂P-N/P-CC exhibits impressive HER catalytic performance, outperforming benchmark Pt/C catalysts at only 7.85% equivalent of Pt; meanwhile, Rh₂P-N/P-CC largely surpasses the RuO₂ catalyst during OER catalysis in alkaline media. As a bifunctional electrocatalyst, Rh₂P-N/P-CC catalyzes stable electrochemical water splitting of 200 mA cm^–1 under 1.7 V. This work reports a feasible strategy to integrate three-dimensional electrodes for high performance water electrolysis.