Ultra-thin carbon-shell coated Ru/RuO2@C with rich grain boundaries for efficient and durable acidic water oxidation

Abstract

Developing an acid-stable oxygen evolution reaction (OER) catalyst is essential for efficient water splitting; however, high overpotentials and poor stability severely hinder its development. Herein, we present the synthesis of ultra-thin carbon shell-coated grain boundary-rich Ru/RuO₂ nanoparticles by molecule-assisted pyrolysis and a subsequent oxidation strategy, assembled into flexible nanosheets. Ru/RuO₂@C is reported as a stable and active acidic OER catalyst that exhibits an ultralow overpotential of 173 mV in 0.5 M H₂SO₄ and a low degradation rate (0.075 mV h⁻¹) over a 120 hours stability test. The systematic experimental results reveal that the carbon layer with high electrical conductivity acts as a protective layer against Ru/RuO₂ dissolution and enhances the stability of the catalyst. The presence of grain boundaries within the core–shell structure enhances the catalytic activity of the catalyst, and the compression or stretching of the lattice strain at the grain boundaries results in faster electron transport at the electrode/electrolyte interface, thus providing more active sites for the OER. The outstanding activity and long-term stability indicate that Ru/RuO₂@C could act as an efficient anode catalyst in proton exchange membrane (PEM) electrolyzers for water splitting.