Dynamics of Water Dissociative Adsorption on TiO₂ Anatase (101) at Monolayer Coverage and Below

Abstract

TiO2 anatase is a functional material that is exploited in several technological devices from photovoltaics to energy storage, water splitting, and solar-to-fuel photocatalysis. In this context, numerous theoretical studies addressed the interaction of water with the most stable anatase (101) surface and reported undissociated molecular adsorption. However, recent experiments on such surface facet at low water coverage pointed out the presence of OH groups. Motivated by these findings, we report here a first-principles investigation on the adsorption and dissociation at low (θ = 0.25) and full (θ = 1) coverage of the first water monolayer at the (101) anatase surface at 300 K with metadynamics. Our simulations show barrierless water adsorption, and at the same time, the dynamic nature of titania-water interactions allows for the dissociation of water and the possible formation of a partial hydroxylated surface at room temperature. These results highlight the relevance of dynamic in modeling surface-water interactions and provide new insights into the physicochemical properties of the pristine anatase TiO2(101) surface in an aqueous environment.