Effect of water on formic acid and formaldehyde decomposition on the TiO 2 (110) surface

H Zhou and SS Liu and SL Yuan, CHEMICAL PHYSICS, 586, 112378 (2024).

DOI: 10.1016/j.chemphys.2024.112378

The catalytic and photocatalytic performance of TiO 2 in air pollutant degradation is significantly influenced by the adsorption of water. Here, we explore the molecular mechanism of formic acid and formaldehyde decomposition and their interaction with water on the TiO 2 (1 1 0) surface, employing density functional theory (DFT) calculations and reactive molecular dynamics (RMD) simulations. RMD simulations indicate that due to the competitive adsorption of water at the surface Ti site, formic acid predominantly exists in a monodentate dissociative adsorption form on the TiO 2 (1 1 0) surface. Moreover, on the TiO 2 (1 1 0) surface, water molecules inhibit the adsorption and dissociation of formic acid, but they facilitate that of formaldehyde, forming methanediol (*CH 2 OHO) and dioxymethylene (*CH 2 O 2 ). DFT calculations suggest that the formation pathway of *CH 2 OHO or *CH 2 O 2 is energetically favorable, but the formation of formate is difficult. This contrasts with the adsorption of formaldehyde on the anatase surface, where formate species are formed.

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