Electronic structures of hydroxylated low index surfaces of rutile and anatase-type titanium dioxide

Abstract

Different surface planes of various types of TiO2 crystals have diverse catalysis effects on the splitting of H2O and H2 and the electronic structures of the formed hydroxylated titanium dioxide...

Tuning the water-splitting mechanism on titanium dioxide surfaces through hydroxylation

“…The 101 surface of anatase-TiO 2 , 110 surface of rutile-TiO 2 , and 210 surface of brookite-TiO 2 were chosen, being denoted as A-101, R-110, and B-210, respectively. Similar to that in our earlier investigations, 31 the surface hydroxyl group generated by the splitting of water on a pure surface was labeled OH1 while the surface hydroxyl group generated by the splitting of H 2 O on an oxygen-deficient surface or H 2 on a pure surface was labeled OH2. As reported by Valdes et al , 28 there are two distinct types of O* intermediates on the TiO 2 surface for the OER process: one is an O atom that is hanging on the surface (designated as O d *), and the other is a structure with the chemical formula Ti–O–O–Ti that reacts with surface oxygen to generate peroxide (designated as O p *).…”

“…In accordance with our earlier research, 31 the A-101, R-110, and B-210 surfaces were each modified with hydroxyl groups of the OH1 and OH2 types. Fig.…”

“…In our previous study, we explored the surface hydroxyl groups of TiO 2 and obtained two types of hydroxyl groups (OH1 type and OH2 type). 31 Based on this hydroxyl group model, the thermodynamic reaction process on the surfaces of anatase (101), rutile (110), and brookite (210) with two types of hydroxyl groups was investigated in this work. The selectivity of products, the rate-determining step, and the overpotential of the OER process were examined through the calculation of the Gibbs free energy of the adsorption intermediates of OH, O, and OOH on different hydroxyled surfaces (*OH, *O, and *OOH).…”

Untangling product selectivity on clean low index rutile TiO2 surfaces using first-principles calculations

“…18 A recent article that calculated the electronic structures of hydroxylated low-index surfaces of rutile and anatase titanium dioxide, suggested that hydroxyl-bridged surfaces have a lot of potential for photo-electrocatalysis but did not directly assess the catalytic performance of these lowindex facets. 62 In the absence of studies identifying the role of each crystal facet in photocatalytic redox reactions, the understanding of photo-oxidation of water by nano-titania is incomplete as only 64% of particle surfaces are (110). [63][64][65] Thus, computational studies that can separately calculate the properties of each surface are critical to understanding the reactivity of experimental nanostructures.…”

“…Typically, the dissociation of species on surfaces in a water environment are adsorbed oxygen species like hydroxyl-bridges. 62 Before computational effort is invested in fully exploring the reactivity of other low-index surfaces of rutile TiO 2 , a detailed understanding of the complex oxidation of water on each stoichiometric surface is required.…”