Ab initio molecular dynamics of solvation effects and reactivity at the interface between water and ascorbic acid covered anatase TiO₂ (101)

Abstract

In this work, we present a detailed study of the interaction between ascorbic acid (L‐asc) and anatase TiO2 (101) surface both in gas phase and in contact with water by using density functional theory and ab initio molecular dynamics simulations. In gas phase, L‐asc strongly binds the TiO2(101) surface as a dianion (L‐asc2‐), adopting a bridging bidentate coordination mode (BB), with the two acid protons transferred to two surface 2‐fold bridging oxygens (O2c). AIMD simulations show that the interaction between the organic ligand and the anatase surface is stable and comparable to the vacuum one despite the possible solvent effects and/or possible structural distortions of the ligand. In addition, during the AIMD simulations hydroxylation phenomena occur forming transient H3O+ ions at the solid‐liquid interface. For the first time, our results provide insight into the role of the ascorbic acid on the electronic properties of the TiO2 (101), the influence of the water environment on the ligand‐surface interaction and the nature of the solid‐liquid interface.

Unveiling Competitive Adsorption in TiO2 Photocatalysis through Machine-Learning-Accelerated Molecular Dynamics, DFT, and Experimental Methods

“…The density of states (DOS) of TiO 2 and adsorbate molecules affords a deeper assessment of the character of the surface interactions. We calculate a band gap, E g , of 2.42 eV, which is commonly reported in the theoretical literature for anatase . However, we suspect that the calculated trends offer meaningful insights.…”

“…We calculate a band gap, E g , of 2.42 eV, which is commonly reported in the theoretical literature for anatase. 21 However, we suspect that the calculated trends offer meaningful insights. As shown in Figure S4 , adding p CBA to the surface ( Figure S4b ) did not induce changes in the electronic states of TiO 2 , which is contrasted with the inhibitory molecules (except for trimesic acid) resulting in the formation of distinct electronic states, as shown in Figure 3 .…”

“…Well-documented shortcomings of implicit solvation motivated the use of an explicit model of water molecules to better understand the system. As shown by Camellone and co-workers, solvation effects on the anatase TiO 2 surface can be accurately and thoroughly described utilizing ab initio molecular dynamics (AIMD) . Such explicit solvation models necessitate substantially greater computational resources than the implicit models and often require 20 ps simulation times (or longer depending on complexity) to attain relatively equilibrated energetics.…”