Ultrafine Ruthenium Oxide Nanoparticles Supported on Molybdenum Oxide Nanosheets as Highly Efficient Electrocatalyst for Hydrogen Evolution in Acidic Medium

Engineering of efficient, robust and inexpensive Pt-free catalysts for the hydrogen evolution reaction has drawn great attention, and there is a rapidly growing demand for electrochemical water-splitting reactions. Here, we report, for the first time, synthesis of ruthenium oxide nanoparticles supported on molybdenum oxide nanosheets (MoO ₃ @RuO ₂ ). This composite catalyst was prepared sonochemically, followed by calcination of the product in air at 400 °C for one hour. The as-synthesized MoO ₃ @RuO ₂ composite catalyst was used to explore the electro-catalytic hydrogen evolution reaction in acidic medium. Notably, compared to MoO ₃ or RuO ₂ , the composite exhibited high exchange current density of 0.57 mA cm ⁻² , and a current density of 10 mA cm ⁻² was achieved at low overpotential of 110 mV in 0.5 M H ₂ SO ₄ . The Tafel slope of the MoO ₃ @RuO ₂ catalyst was 62 mV dec ⁻¹ and it showed excellent stability. This remarkable performance can be attributed to the synergetic effect generated by the strong interaction between MoO ₃ nanosheets and RuO ₂ nanoparticles, which resulted in enhanced long-term stability as well.