Nature of Interactions at the Interface of Two Water-Saturated Commercial TiO₂ Polymorphs

Abstract

Two commercial TiO2 samples, a 100% anatase\ud and a 100% rutile, were used for the fast field cycling NMR\ud experiments. The results showed a different behavior between\ud the different samples. In particular, water molecules were\ud unbonded to the solid surface for the rutile sample, whereas\ud they appeared to chemically interact with the surface through\ud H-bond formation with the anatase sample. The above\ud findings accord with the generally lower activity of rutile\ud with respect to anatase reported in literature for photocatalytic\ud oxidation reactions in water. The difficulty of water to interact\ud with rutile surface, indeed, could hinder the formation of OH\ud radicals, which are the most important oxidant species

Tailoring Noble Metal-Free Ti@TiO2 Photocatalyst for Boosting Photothermal Hydrogen Production

“…It is worth noting that these values are much lower than the typical activation energy of chemical bonds and has been previously assigned to the diffusion of intermediates at the catalyst surface (Nikitenko et al, 2018). Alternatively, the temperature dependence of photocatalytic reactions can be also related to the dynamics of water Parrino et al, 2017).…”

Structure alteration of a sandy-clay soil by biochar amendments

“…Similar weak H bonds have been also revealed between water and titanium dioxide polymorphs. In the latter case, the H bonds were established between oxygen in water and the hydrogens in the surface hydroxyls of TiO 2 (Conte et al 2013b). Figure 3 shows the proton longitudinal relaxation time distributions for the sandy-clay soil (f bc =0), the soil added with biochar at three different weight fractions (f bc =0.091, 0.23 and 0.33, respectively) and the sole biochar (f bc =1).…”

Morphology control of anatase TiO2 for well-defined surface chemistry

“…Such studies were however mostly done on anatase samples with uncharacterized morphologies or low faceting, [24][25][26][27][28][29] mixed with other TiO 2 phases, [30][31][32][33][34][35][36] or with physisorbed water still present on the surface, [26][27][28][35][36][37][38] thus hampering the understanding of the nature of their surface hydroxyls. Similarly, 1 H NMR studies often show the same traits: uncharacterized morphologies, [39][40][41][42][43] amorphous surfaces, [44][45][46][47][48] mixed phases 36 and the presence of a layer of physisorbed water. 19,36,41,43,47 In order for a sample to display a simple, uniform and comprehensible surface chemistry, morphology control seems to be required to obtain well-faceted crystallites of a specific allotrope with a high majority of a single facet exposed.…”