Scaling Properties of Adsorption Energies for Hydrogen-Containing Molecules on Transition-Metal Surfaces

Density functional theory calculations are presented for ${\mathrm{CH}}_{x}$, $x=0,1,2,3$, ${\mathrm{NH}}_{x}$, $x=0,1,2$, ${\mathrm{OH}}_{x}$, $x=0,1$, and ${\mathrm{SH}}_{x}$, $x=0,1$ adsorption on a range of close-packed and stepped transition-metal surfaces. We find that the adsorption energy of any of the molecules considered scales approximately with the adsorption energy of the central, C, N, O, or S atom, the scaling constant depending only on $x$. A model is proposed to understand this behavior. The scaling model is developed into a general framework for estimating the reaction energies for hydrogenation and dehydrogenation reactions.