Influence of hydration, hydroxylation, and doping of TiO₂(110) on the adsorption and decomposition of sarin: a density functional theory investigation

Metal oxides are promising candidates for the adsorption and decomposition of chemical warfare agents (CWA) and can be the foundations of novel CWA destruction technologies. In this work, we use density functional theory (DFT) to explore how dry, wet and doped states of the metal oxide TiO₂(110), influence the adsorption and chemical dissociation of the nerve agent, sarin. The DFT calculations show that the dissociative adsorption of sarin is more energetically favored than the molecular adsorption for all dry, wet and doped states of TiO₂(110). The calculated energy barrier for the adsorption of sarin on dry TiO₂(110) showed that sarin is initially adsorbed with a molecular configuration, followed by the dissociative process. For the adsorption of sarin on wet TiO₂, under both hydrated and hydroxylated states, the 0.5 H₂O monolayer (ML) showed the lowest adsorption energy compared to the dry and other wetness levels explored. Finally, the adsorption of sarin on TiO₂(110) doped with Hf exhibited lower adsorption energy and higher charge transfer compared with TiO₂(110) doped with Zr and Ge, as well as the undoped systems. These results demonstrate how hydration, hydroxylation, and doping of TiO₂(110) significantly influence the adsorption and decomposition of sarin on this metal oxide.