Sulfur molecule-assisted synthesis of Pt5Ce intermetallic nanoparticles for efficient hydrogen oxidation reaction

Hydrogen fuel cells are promising energy-conversion devices for sustainable hydrogen utilization. In particular, the sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline media remains a major challenge for anion exchange membrane fuel cells. Although Pt-based catalysts serve as benchmark HOR materials because of their high intrinsic activity, their alkaline HOR performance and long-term structural stability are still insufficient for practical operation. Constructing Pt-based intermetallic compounds (IMCs) with rare-earth elements (Ln) offers a promising route to optimize and stabilize Pt sites. However, the controllable synthesis of Pt-Ln IMCs is hindered by the difficult reduction and easy oxidation of Ln species during thermal treatment. Herein, we develop a sulfur-molecule anchoring strategy for the controlled synthesis of Pt5Ce IMCs nanoparticles toward high-performance alkaline HOR. Both 2-propanethiol (PT) and sodium thioglycolate (STG) contain sulfur-bearing functional groups capable of interacting with metal precursors and the carbon support, enabling the regulation of particle size during annealing. Compared with STG, which yields severely aggregated Pt5Ce IMCs with an average particle size of 37.3 nm (Pt5Ce/C-STG), PT enables the formation of uniformly dispersed Pt5Ce IMCs with an average particle size of 2.5 nm (Pt5Ce/C-PT). This difference is associated with the more favorable PT-derived precursor environment during precursor impregnation and subsequent thermal annealing. As a result, Pt5Ce/C-PT delivers a current density of 2.3 mA cm−2 at an overpotential of 150 mV, outperforming Pt5Ce/C-STG (1.5 mA cm−2) and commercial Pt/C (1.4 mA cm−2). Density functional theory calculations reveal that incorporated Ce atoms optimize *H and *OH adsorption, lower the potential-determining-step energy barrier, and weaken *CO adsorption, accounting for the enhanced alkaline HOR performance of Pt5Ce IMCs.