Ultrastable Ruthenium-Based Electrocatalysts for Hydrogen Oxidation Reaction in High-Temperature Polymer Electrolyte Membrane Fuel Cells

Ruthenium (Ru) is a promising electrocatalyst for hydrogen oxidation reaction (HOR) due to the similar metal hydrogen bond energy to Pt. However, Ru is easily deactivated or dissolved under an oxidation potential, which makes it unavailable in proton exchange membrane fuel cells. In this work, ultrastable Ru-based electrocatalysts for HOR in high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) were developed by Mo doping. Under the operation conditions of HT-PEMFCs, thermal reduction inhibited the production of amorphous Ru oxide (RuO₂) in the Ru-based electrocatalysts during the HOR. Mo doping significantly improved the stability of the electrocatalyst by decreasing the reduction temperature of RuO₂ and accelerating the HOR by reducing the adsorption of H*. RuMo/C exhibited excellent HOR activity at high temperatures due to thermal reduction inhibition of electrooxidation; the fabricated HT-PEMFCs exhibited long-term stability and a 1050 mW cm⁻² peak power density, comparable to the commercial Pt catalyst. This work provides a novel strategy for designing electrocatalysts by combining material intrinsic properties and work conditions, which could promote the development of advanced electrocatalysts for HT-PEMFCs.