Stabilizing a Ru single atom catalyst through electronic metal–support interaction with a NiCo2O4 support for overall water splitting and urea electrolysis

Abstract

Single atom catalysts have manifested themselves as a new frontier in heterogeneous catalysis owing to their maximum atom utilization efficiency. However, their tendency to aggregate leads to poor stability, which limits their application. Herein, we overcome this challenge by stabilising a noble metal single atom catalyst through anchoring it on a metal oxide support, where a strong electronic metal–support interaction prevents their aggregation. Specifically, we have synthesized Ru single atoms anchored on the NiCo₂O₄ support by using an ultra-low amount of Ru. XAS and HAADF-STEM analysis confirm the presence of isolated Ru single atoms on the support. These isolated Ru atoms have a high density of unoccupied orbitals, which is favourable for electrocatalytic activity. The synthesized Ru single atom catalyst (Ru-SAC) on NiCo₂O₄ shows superior activity for overall water splitting with a cell potential of 1.57 V, showing excellent stability of 60 h. The synthesized Ru-SAC NiCo₂O₄ is also active in urea electrolysis and exhibits a cell potential of 1.41 V to generate a current density of 10 mA cm⁻². Density functional calculations reveal that supported single Ru atoms optimized the binding energies of the intermediate of both the HER and OER.