Assembled RhRuFe Trimetallene for Water Electrolysis

Abstract Industrializing water electrolyzers demands better electrocatalysts, especially for the anodic oxygen evolution reaction (OER). The prevailing OER catalysts are Ir or Ru‐based nanomaterials, however, they still suffer from insufficient stability. An alternative yet considerably less explored approach is to upgrade Rh, a known stable but moderately active element for OER electrocatalysis, via rational structural engineering. Herein, a precise synthesis of assembled RhRuFe trimetallenes (RhRuFe TMs) with an average thickness of 1 nm for boosting overall water splitting catalysis is reported. Favorable mass transport and optimized electronic structure collectively render RhRuFe TMs with an improved OER activity of an overpotential of 330 mV to deliver 10 mA cm −2 , which is significantly lower than the Rh/C control (by 601 mV) and reported Rh‐based OER electrocatalysts. In particular, the RhRuFe TMs‐based water splitting devices can achieve the current density of 10 mA cm −2 at a low voltage of 1.63 V, which is among the best in the Rh‐based bifunctional catalysts for electrolyzers. The addition of Fe in RhRuFe TMs can modulate the strain/electron distribution of the multi‐alloy, which regulates the binding energies of H * and OH * in hydrogen and oxygen evolution reactions for achieving the enhanced bifunctional OER and HER catalysis is further demonstrated.