Conversion of solar energy into chemical form is possible using artificial means, such as the use of a highly efficient system in which solar energy splits water into oxygen and hydrogen fuels. Efficient photocatalytic water-splitting remains an open challenge for researchers across the globe, and, despite significant progress, several aspects of the reaction, including the charge transfer mechanism, are not fully understood. Density functional theory combined with density matrix equations of motion were used to identify and characterize the charge transfer mechanism involved in the dissociation of water. A periodic and porous silica substrate was simulated, with Ti<sup>4+</sup> ions embedded on the inner pore wall, and water molecules located within the pore and near the Ti atom. Photo-induced dynamics of excitation lead to the discovery of electron and hole trap states that could facilitate a chemical reaction. A particular trap state located within the silica substrate was determined to lengthen relaxation time, and may favor a chemical reaction. The location of the trap state indicates that the silica substrate plays an important role in electron and hole dynamics. Furthermore, the optimization of catalytic efficiency should include enhancement of the substrate, as well as the catalytic photoactive sites.

Photo-induced excited state dynamics: water-splitting in titanium-doped microporous silica

252nd National Meeting (2016)

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