Tungsten Carbide Supports for Single-Atom Platinum-Based Fuel-Cell Catalysts: First-Principles Study on the Metal–Support Interactions and O₂Dissociation on WxC Low-Index Surfaces

As a first attempt to understand the role of tungsten carbide (WxC) surfaces as a support of single-atom platinum-based catalysts, the adsorption properties of Pt on WxC(100) surfaces and its impact on O2 dissociation are investigated using first-principle DFT calculations. Pt adsorptions on the dominant low-index WxC surfaces are found to be stable on various adsorption sites. The adsorbed Pt atoms are unlikely to diffuse into the bulk and, in general, resistant to bulk-like clustering. A correlation between the adsorption energies and the surface energies is observed; that is, the stronger adsorption of Pt atoms on the surfaces, the lower the surface energies of the Pt/WxC(100) systems. This leads to the further downshift of d-band center of the surface slabs. From the stability of Pt atoms on different WxC low-index surfaces, it is conclusive that WxC(100) surfaces are effective supports for single-atom platinum catalysts. Preliminary DFT results of O2 dissociation on single-atom Pt–WxC(100) system show the generation of new interface sites that thermodynamically favor oxygen dissociation, even at high coverage.