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O: Fachverband Oberflächenphysik

O 24: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces I

O 24.1: Hauptvortrag

Dienstag, 13. März 2018, 10:30–11:00, MA 005

Modelling Photo-electrochemistry on Oxide Surfaces — •Harald Oberhofer — Technical University Munich, Garching, Germany

The role computer modelling plays today in understanding and optimising catalysts for photo-electrochemical reactions is undisputed. Yet, state of the art simulation approaches tend to rely on a number of assumptions and simplifications which---especially on oxide surfaces---may not be fully justified. For example, simulation of the all-important water oxidation reaction is mainly based on idealised surfaces and the computational hydrogen electrode (CHE) approach, which evaluates the thermodynamic feasibility of a catalyst looking at pathways where each hydrogen abstraction is coupled to the removal of one electron (PCET). The precise reactive site of the catalyst is thereby viewed as irrelevant, based on the premise of idealised surfaces. Yet, specifically on semi-conducting oxides both the assumption of PCET and of pristine, defect-free surfaces are not necessarily fulfilled.

In my presentation I will outline some of the steps necessary to augment theoretical approaches that so far have been geared towards the simulation of metal surfaces under ideal conditions to oxides under realistic conditions. There, the focus will lie on the nature of the reactive site---considering e.g. defects able to attract reaction-driving localised charge carriers---and the appearance of free energy barriers and their influence on reaction kinetics. Finally, for a realistic model of photo-electrochemical reactions occurring on the solid-liquid interface I will examine the role the solvent itself.