Nano Energy Research

Optimum control of the photocatalytic water fission on anastasis surfaces

Principal Investigator: Prof. Dr. Thorsten Klüner
Collaboration: Prof. Dr. Katherina Al-Shamery, Prof. Dr. Niklas Nilius, Prof. Dr. Walter Neu

The goal of this theoretical PhD project will be a quantum dynamical description of the photoinduced dissociation of water on a TiO2(101) anatase surface at an atomistic level and a femtosecond timescale. Elementary processes of the photochemical bond activation will be investigated and optimal control will be used for steering. In cooperation with experimentalists, a fundamental mechanistic understanding of this highly reactive photocatalytic material will be achieved in order to understand the foundations of a hydrogen-based energy economy on the molecular level.

The following questions will have to be answered by simulations: Does water dissociate on a perfect anatase surface and what are the corresponding adsorption energies and geometries? How does the system evolve after electronic excitation of the adsorbate? Is it possible that this process leads to a significant dissociation, and what are the differences as compared to the electronic ground state?

In this research project, the splitting of water on anatase surfaces will be investigated by modern quantum chemical and quantum dynamical methods for the first time. Along these lines, the method of local increments will be applied for the accurate treatment of electron correlation effects of electronically excited states[i].

A quantum dynamical treatment of the process of photocatalytic water splitting is mandatory since quantum effects such as tunneling do preferentially occur in processes involving light elements such as hydrogen. After the calculation of high-dimensional potential energy surfaces for the electronic ground state and electronically excited adsorbate-substrate states, stochastic wave packet calculations will be performed in the first place[ii]. Subsequently, these calculations will be augmented by quantum dynamical studies of optimal control by ultrashort laser pulses in which quantum dissipative processes (energy relaxation and dephasing) will be taken care of explicitly within the framework of an effective Surrogate Hamiltonian[iii].

 


[i] H.Stoll, Phys. Rev. B 46 (1992), 6700.

[ii] T. Klüner, Prog. Surf. Sci. 85 (2010), 279.

[iii] E. Asplund, T. Klüner, Phys. Rev. Lett. 106 (2011), 140404.