Spin Effects in Chemisorption and Catalysis

In this work, we show using density functional theory calculations that controlling the spin state of the surface of magnetic metals has a substantial effect on their chemical properties. For a range of adsorbates, the adsorption energy is shown to be stronger on non-spin polarized surfaces than on spin polarized ground state surfaces. This is true for Fe, Co, and Ni surfaces, and the result is the same for three commonly used exchange-correlation functionals. We further discuss the origin of the effect in terms of the surface electronic structure and show that a simple model based on the d-band model of adsorption can explain the effect. Finally, we discuss how spin effects may be used to control surface reactivity and provide guidance on how to alter the surface spin state, e.g., adding a metal promotor.