Janus Dumbbell Ru–Pt Nanoparticles on Titanium Oxynitride Boost Hydrogen Evolution Across pH

While platinum nanocatalysts exhibit outstanding activity for the hydrogen evolution reaction (HER), their high cost and scarcity underscore the need to develop more efficient and sustainable alternatives. This work reports a highly active, stable, and cost-effective electrocatalytic composite for HER consisting of bimetallic Janus dumbbell Ru─Pt nanoparticles deposited on a titanium oxynitride-graphene support (Ru─Pt/TiON─C). Ru─Pt/TiON─C nanocomposite with particularly low metal loading of only 1.85 wt.% Pt and 5.5 wt.% Ru outperforms the 20 wt.% Pt/C benchmark catalyst in both acid and alkaline electrolytes. A joint experimental-theoretical approach, combining electrochemical measurements, transmission electron microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations, reveals that the improved performance and metal utilization stem from the intimate Ru─Pt─TiON interface. These findings point to beneficial support effects arising from TiON, together with Ru-induced modification of the Pt active sites that promotes more favorable hydrogen adsorption thermodynamics. Such a catalyst structure results in exceptional HER activity of Ru─Pt/TiON─C across the entire pH range.