Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 61: Focus Session: Nanoscale Insights into Interfacial Electrochemistry I
O 61.7: Vortrag
Mittwoch, 14. März 2018, 12:45–13:00, HE 101
Quasi-atomistic insight into Au oxide reduction under realistic working conditions — •Jonas H. K. Pfisterer, Ulmas E. Zhumaev, and Katrin F. Domke — Max Planck Institute for Polymer Research, Mainz, Germany
The rational design of improved electrochemical devices, e.g. fuel cells, depends on the atomistic understanding of the underlying reaction processes under realistic working conditions. The ability of tuning the Fermi level and employing highly sensitive molecular detection methods can provide valuable insights into molecular adsorption/desorption on the surface. Here, we investigate the reduction of AuOx surfaces in contact with an electrolyte by in-situ surface-enhanced Raman scattering (EC-SERS). We have performed potential-jump experiments in which we stepwise vary the applied potential to induce either AuOx formation or Au surface recovery. As a function of potential, we observe a splitting of the AuOx/(AuOH) peak at 585 cm−1 into two peaks that are assigned to AuOx and AuOH based on H/D exchange experiments. Further, the AuOH peak exhibits Raman intensity oscillations with time that can possibly be ascribed to subsurface OH moving to the surface. Accompanying Raman peaks at 240 and 1200 cm−1, complemented with in-situ IR absorption experiments, indicate that the adsorption of SO42− starts only after initial AuOx reduction.
Our potential-jump experiments on AuOx surfaces reinforce the role of OH species for the reduction process even in acidic media and represent an interesting approach to gain quasi-atomistic insights into surface reactions under realistic working conditions.