Enhanced Photocatalysis of TiO2 with a Pt Co-Catalyst

TiO₂ is an affordable photocatalyst for generating hydrogen gas, a clean-burning source of energy, from water, organic waste, and UV-visible light. Experiments show that the photocatalytic rate can be enhanced by coupling TiO₂ with a small amount of Pt co-catalyst. To determine how Pt alters the electronic properties of the photocatalyst, ab initio density functional theory is used to model two common surfaces of anatase TiO₂. Periodic slab structures that expose (101) and (001) surfaces are created with and without Pt adsorbed to the surface. The surface energy, electron density difference, and density of states are calculated for each slab to observe how the presence of Pt enhances photocatalysis. The TiO₂ below adsorbed Pt undergoes a p-to-n semiconductor transition, which enhances electron-hole stability by drawing electrons away from nearby clean TiO₂ surfaces.