Bifunctional mechanism of hydrogen oxidation reaction on atomic level tailored-Ru@Pt core-shell nanoparticles with tunable Pt layers

Anion exchange membrane fuel cells (AEMFCs), as the next generation of cost-effective fuel cells, have attracted renewed attention in recent years. One of the existent challenges to the AEMFCs is the sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline solution. The alkaline HOR mechanism is yet in debate, which would be a major barrier to the design of high-performance catalysts. Here, we explore the HOR mechanism on graphene-supported Ru@Pt core-shell nanoparticles. The Pt shell was precisely tailored at atomic monolayer level through controlling Cu underpotential deposition (UPD)-Galvanic displacement (GD) cycle. The relationship between the HOR electrocatalytic activity and the electronic structure of the catalysts has been investigated based on the results from electrochemical rotating disk electrode and X-ray photoelectron spectroscopic characterizations. We find that the hydrogen-binding energy (HBE) is not the sole descriptor of HOR activity, the reactive oxygen species on the catalyst surface also promotes the HOR kinetics through the bifunctional mechanism. This research offers the fundamentals for designing high performance HOR catalysts in alkaline solution and contributes to the commercial application of hydrogen fuel cells.