Atomistic Simulation of Dissipative Charge Carrier Dynamics for Photocatalysis
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ATOMISTIC SIMULATION OF DISSIPATIVE CHARGE CARRIER DYNAMICS FOR PHOTOCATALYSIS Talgat M. Inerbaev1), Dmitri S. Kilin2), James Hoefelmeyer2) 1)
Gumilyov Eurasian National University, Astana, Munaitpasov st. 5, 010008, Kazakhstan 2) Department of Chemistry, University of South Dakota, Vermillion SD 57069, USA
ABSTRACT Photo-excitation of high surface area semiconductor nanorods decorated with surface catalyst particles are investigated. DFT-based simulation is applied to the charge transfer dynamics at the interface of the supported nanocatalyst by modeling dynamics of photo-excitations. The modeling is performed by reduced density matrix method in the basis of Kohn-Sham orbitals. The energy of photo-excitation is dissipating due to interaction with lattice vibrations, treated through non-adiabatic coupling as the electron/hole pair relaxes to the conduction / valence band edges. The methodology is applied to TiO2 nanorod modeled as a periodic anatase (100) slab functionalized by minimalistic nano-clusters or doping. Simulations of these models demonstrate the formation of charge transfer state in both time and frequency domain. Computed charge dynamics 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. INTRODUCTION and METHOD 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, hole excitation 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. We model dynamics of photo-excitations in functionalized semiconductor nano-structures. The modeling is performed by reduced density matrix method in the basis of Kohn-Sham orbitals. The energy of photo-excitation is dissipating due to interaction with lattice vibrations, treated thro
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