Not a Mere Decoration: Impact of Submonolayer Coverages of Nickel on Fundamental Properties of Platinum

Abstract

Theoretical insights have been gained into nickel adatom interaction with model platinum basal planes, and evolution of their fundamental properties with growing nickel surface coverage has been analyzed. Calculations have been performed using density functional theory with the Perdew-Burke-Ernzerhof exchange correlation functional and dipole corrections. The presence of a single Ni atom appreciably affects the Pt surface, lowering the work function and shifting the d-band center position away from the Fermi level of Pt atoms in contact with Ni. At increasing coverage, Ni bonding strength with Pt increases and plain structures are formed on all considered surfaces, although the initial tendencies, seen for the Pt fundamental properties upon Ni adsorption, do not change. Compared to reported experimental data, results suggest that lowering of the work function, φ, of Pt(111) upon Ni adsorption may facilitate charge transfer through the electric double layer, improving the rate of the hydrogen evolution reaction in alkaline media on Ni-modified Pt(111) surfaces. Hence, this rate-promoting effect would be expected to be lower for Pt(110) and (100) because of the lower impact of Ni adatoms on φ for these two surfaces. Results of the present study improve the current understanding of adatoms' electronic effects on the substrate and contribute to the scientific basis for the systematic design and development of Pt-based catalysts. © 2022 American Chemical Society.