Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 42: Materials for Energy Storage I (joint session KFM/CPP)

CPP 42.4: Vortrag

Mittwoch, 14. März 2018, 10:40–11:00, EMH 025

Water Adsorption on a n-Si/NiO Photoanode - Cryo Photoelectron Spectroscopy in the Frozen Electrolyte Approach — •Mathias Fingerle, Sven Tengeler, Wolfram Calvet, Thomas Mayer, and Wolfram Jaegermann — Surface Science Division, Department of Materials Science, Technical University Darmstadt, Otto-Berndt-Str. 3, D-64287 Darmstadt, Germany

In the course of the BMBF InnoEMat project Fundamentals of Electrochemical Interfaces: Semiconductor/Electrolyte, elemental charge transfer processes at solid/liquid interfaces are studied via cryo photoelectron spectroscopy and post-operando experiments. Here, the interaction of water with a magnetron-sputtered nickel oxide thin film on an n-type silicon photo-anode is investigated in perspective to oxygen evolution. The substrate was exposed in-situ stepwise to gas phase water up to 10 L at liquid N2 temperature and analyzed via X-ray and UV photoelectron spectroscopy in the so called frozen electrolyte approach. Photoemission of the pristine NiOx layer shows the presence of stoichiometric NiO and Ni2O3 as well as of non-stoichiometric phases. In the monolayer range, molecular and dissociative adsorption is detected assigned to the NiO respective Ni2O3 phase. Initially, the emissions of the molecular adsorbed water species interacting with NiO are found at 0.8 eV lower binding energies as compared to water related emissions for higher coverages with binding energies commonly assigned to H2O-H2O interaction. In addition to the chemical analysis, the electronic structure of the n-Si/SiOx/NiOx/H2O photoanode is measured and discussed.