Support Effects of Microwave-Synthesized Ru-Based Catalysts on Their Hydrogen Evolution Performance in Acidic Media

Ruthenium-based catalysts supported on TiO2, SnO2, and WO3 were synthesized via a microwave-assisted rapid reduction method and evaluated for the hydrogen evolution reaction (HER) in acidic media. The Ru species existed as highly dispersed nanoclusters, as confirmed by XRD and TEM, and the catalytic activity was strongly dependent on the oxide support. Ru/TiO2 exhibited the best HER performance, achieving an overpotential of 187 mV at 10 mA·cm−2 and a Tafel slope of 97.56 mV·dec−1. While particle size differences (1.8–3.7 nm) did not account for the activity trend, XPS revealed distinct metal–support interactions that modulated the electronic state of Ru. Ru/TiO2 showed an intermediate electron depletion that optimizes the Ru-H binding strength, explaining its superior kinetics. Regulation of Ru loading further identified Ru/15TiO2 as the optimal catalyst, exhibiting low charge transfer resistance and excellent stability over 17 h. This study highlights the critical role of support-induced electronic modulation and loading engineering in designing efficient Ru-based electrocatalysts for acidic HER.