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.

Spectroscopy of Radicals, Clusters, and Transition States Using Slow Electron Velocity-Map Imaging of Cryogenically Cooled Anions

“…There is considerable interest in understanding the interaction of water with TiO 2 and ZrO 2 . , For example, photocatalyzed water splitting on TiO 2 and ZrO 2 surfaces has the potential to play a key role in solar-powered fuel cells. − These considerations have motivated theoretical − and experimental − investigations of clusters of water with TiO 2 and ZrO 2 . Electronic structure calculations by Dixon and co-workers on neutral TiO 2 ·H 2 O and ZrO 2 ·H 2 O clusters show that water splitting to form a dihydroxy species (i.e., TiO­(OH) 2 ) is highly exothermic and proceeds over a small barrier. , By carrying out photoelectron spectroscopy of the anions TiO 2 – ·H 2 O and ZrO 2 – ·H 2 O, one can determine whether dissociative chemisorption occurs in the anions and if it does, explore the spectroscopy of the neutral dihydroxy species.…”

Modeling Single‐Atom Catalysis

“…Alternative ways to map the potential energy surface are based on advanced free energy surface sampling techniques such as metadynamics. [93,94] Metadynamics is a technique that allows the estimation of the free energy of complex molecular systems and the acceleration of rare events. It is based on "filling" the potential energy by a sum of Gaussians centered along the trajectory followed by an appropriate set of collective variables, thus forcing the system to migrate from one minimum to the next.…”

Spectroscopy of radicals, clusters, and transition states using slow electron velocity-map imaging of cryogenically cooled anions

“…There is considerable interest in understanding the interaction of water with TiO2 and ZrO2. [81][82] For example, photocatalyzed water splitting on TiO2 and ZrO2 surfaces has the potential to play a key role in solar-powered fuel cells. [83][84][85] These considerations have motivated theoretical [86][87][88][89] and experimental [90][91][92][93] investigations of clusters of water with TiO2 and ZrO2.…”