DISSIPATIVE CHARGE CARRIER DYNAMICS FOR PHOTOCATALYSIS

摘要

High surface-area semiconductor nanorods decorated with RuO2 as a surface functional component are investigated. Main attention is focused on the most important and least explored part of the problem: hole transfer in oxidizing nanocatalyst. DFT-based simulation for the charge transfer dynamics at the interface of the RuO2 nanocatalyst and TiO2 nanorod is applied. A TiO2 nanorod is modeled as a periodic anatase (100) slab functionalized with RuO2 nanocatalyst. In this model, a photoexcitation promotes a non-equilibrium state of the material, so that the electronic states are recalculated for each atomic configuration along molecular dynamics trajectory produced during the simulation to compute the coupling between the electronic and nuclear degrees of freedom. Photon-to-exciton conversion efficiencies and photo-excited charge carrier lifetime are estimated. According to computed dynamics, the hole relaxes to valence band maximum faster than electron to the conduction band minimum. This leads to creation of positively charged areas on the nanorod surface that is an important prerequisite for oxidation catalysis. Our computation identifies optimal composition and morphology of nanocatalyst for such applications as water splitting for hydrogen production or solar cells.