Lattice-confined Ru clusters with high CO tolerance and activity for the hydrogen oxidation reaction

An efficient catalyst for the hydrogen oxidation reaction (HOR) must maintain an oxide-free metal surface in a relatively high potential range. This requirement automatically excludes ruthenium because it is susceptible to oxidation in the hydrogen adsorption/desorption potential region. Herein we report Ru clusters partially confined in the lattice of urchin-like TiO 2 crystals (Ru@TiO 2 ) that can effectively catalyse the HOR up to a potential of 0.9 V RHE with a mass activity higher than that of a PtRu catalyst under both acidic and basic conditions. Moreover, the HOR activity of this Ru@TiO 2 catalyst is not affected by 1,000 ppm CO impurity. Even at a high CO content of 10 vol%, Ru@TiO 2 still selectively catalyses the HOR. Confined Ru clusters grow along the lattice of TiO 2 with abundant Ru–Ti bond formation. Such atomically connected co-crystals offer efficient electron penetration from electron-rich TiO 2 to Ru metal, leading to sluggish CO adsorption kinetics during the HOR.