Cluster Beam Deposition of Ultrafine Cobalt and Ruthenium Clusters for Efficient and Stable Oxygen Evolution Reaction

Ultrafine cobalt and ruthenium clusters are deposited on carbon paper substrates by cluster beam deposition using a matrix assembly cluster source and a pulsed microplasma cluster source, respectively. When used to catalyze the oxygen evolution reaction (OER), the cobalt and ruthenium clusters show electrocatalytic performance superior to the state-of-the-art Ru/C and RuO₂ nanoparticle catalysts on both a mass and a specific-surface-area basis. Typically, the cobalt clusters can deliver 10 mA cm^-2 at a low overpotential of 320 mV and show a small Tafel slope of 50 mV dec^-1 and a mass-based turnover frequency of 0.01 s^-1 at an overpotential of 300 mV, outperforming many cobalt-based OER catalysts.