Linear scaling of charge transfer versus work function of Ammonia chemisorption on X-metal (X = Ag, Au, Pd, and Pt) surface

Abstract

Although the d-band center theory can efficiently describe the interaction between gas molecules and transition metal surfaces, the specific reaction process and detailed adsorption criteria remain unclear. Therefore, we systemically investigated the adsorption process and mechanism of Ammonia (NH3) molecules on transition metal (i.e., Ag, Au, Pd and Pt) surfaces using first-principles calculations. Results indicate that the NH3 molecule undergoes chemisorption on the Pt (111) surface with considerable charge transfer and adsorption energy, indicating that Pt metal is a promising NH3-sensitive material. Furthermore, the chemisorption primarily entails the highest-occupied molecular orbital (HOMO) of NH3, and the metal atoms conform perfectly to the principles of energy-level matching, wave function matching, and maximal orbital wave function overlap. Notably, a linear relationship exists between the charge transfer of NH3 and the work function of X-metal substrates. Our findings provide a feasible way to efficiently design NH3-sensitive materials for experiments.