Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 13: Solid-Liquid Interfaces I: Electrocatalysis and Photoelectrochemistry

O 13.7: Vortrag

Montag, 1. April 2019, 16:30–16:45, H16

The Effect of DFT Functionals on First-principles Estimates of the Free Energy Barrier of Water Deprotonation on TiO₂(110) — •Ahmad Agung, Thomas Stecher, Karsten Reuter, and Harald Oberhofer — Technische Universität München

Water splitting on TiO₂ is an important model reaction for photo-electrocatalytic processes in general. Recently, we calculated the kinetic barrier of the first deprotonation step on the rutile TiO₂(110) surface based on ab-initio molecular dynamics (AIMD) and utilizing QM-MM embedding, explicit solvation, and the HSE06 hybrid functional.[1] However, the high computational cost of hybrid DFT and the size of the system render such an approach infeasible e.g. for possible catalyst screening studies. In our contribution, we therefore investigate a different approach based on semi-local DFT dynamics and a statistical re-weighting of snapshots with HSE06. We show that, although semi-local DFT by itself would give qualitatively wrong results, the re-weighting procedure restores the correct shape of the free energy profile along the reaction coordinate. We discuss the reasons for the failure of semi-local DFT and highlight remaining sources of error in the re-weighting procedure, leading to still present over-estimation of the free energy barrier height. This work is an important step towards a computationally feasible simulation protocol for free energy barriers in photo-electrocatalytic processes.

[1] T. Stecher, K. Reuter and H. Oberhofer, Phys. Rev. Lett. 117, 276001 (2016).