Discovery of Highly Active Noble-Metal-Lean Mo−Ru Electrocatalysts for Hydrogen Evolution

The discovery of high-performance electrocatalysts for water electrolysis is highly important. We use a strategy for catalyst discovery based on high-throughput screening of a broad range of materials compositions on a thin-film materials library to identify noble-metal-lean multi-metal compositions with high activity towards the hydrogen evolution reaction in alkaline electrolyte. We demonstrate this strategy using a quaternary materials library containing Mo, Ag, Ti, and Ru fabricated by combinatorial magnetron sputtering on a 10 cm diameter wafer providing 342 measurement areas. Surprisingly, binary Mo−Ru-containing catalyst compositions with comparatively low Ru content exhibited the highest activity. Using the polymer/metal precursor-based spray technique, Ni foam electrodes were modified with the Mo−Ru hit compositions and evaluated in a model electrolyzer in membrane electrode assembly (MEA) configuration. The electrodes showed a very low overpotential of only 132 mV at a comparatively high current density of −2 A cm⁻² and a 24 h electrolysis stability at −1 A cm⁻² with no observable degradation after the initial electrode conditioning.