Understanding and tailoring the interactions between hydrogen (H) atoms and catalytic surfaces is critical to developing electro-catalysts with less platinum (Pt). Tungsten carbide (WC) is a possible valence isoelectronic substitute for Pt. Using first-principles quantum mechanics calculations, we systematically investigate H binding to WC(0001) and Pt(111) surfaces. Moreover, inspired by recent experiments on hybrid monolayer-Pt/WC catalysts, we study H adsorption on these hybrid surfaces. We consider both W and C terminations and vary the number of Pt layers. We predict that the H binding energy (HBE) plateaus rapidly with the number of Pt layers and that a monolayer of Pt on a WC substrate has a similar HBE to that of pure Pt. This corroborates the experimental observation that the two systems exhibit similar electrochemical activities. Increasing the number of Pt layers leads to a slight increase in the HBE and a projected decrease in catalytic activity. Through various electronic structure analyses, we show that the similarity in activities is due to an intrinsic alteration of the character of the Pt/WC surface rather than a similarity to the pure Pt surface. Our findings provide guidance for tuning parameters that affect catalytic activity by controlling WC surface termination and Pt overlayer thickness.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry