Intrinsic Role of Excess Electrons in Surface Reactions on Rutile TiO2 (110): Using Water and Oxygen as Probes

Reactions on catalytically active surfaces often involve complex mechanisms with multiple interactions between adsorbates and various subsequently formed intermediates, and a variable number of excess electrons further complicates the involved mechanisms. Experimental techniques face challenges in precisely tuning or determining the number of excess electrons and in elucidating these complex reactions. In this work, the thermodynamic details and reaction pathways of interactions between the most prevalent and important molecular species, H2O and O-2, on a prototypical rutile TiO2 (110) surface are investigated using density functional theory calculations on 10 elementary reaction steps with the intention of gaining further insight into surface catalysis. The results suggest that the final product is independent of the reaction pathway when the number of excess electrons is sufficient. The intrinsic role of excess electrons at the reaction level is thus proposed to extend the understanding of the origin, distribution, and transfer of excess electrons. Such an understanding is beneficial to develop high-performance catalysts.