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O: Fachverband Oberflächenphysik
O 80: Poster Session VI: Poster to Mini-Symposium: Electrified solid-liquid interfaces I
O 80.1: Poster
Wednesday, March 3, 2021, 13:30–15:30, P
Vibrational Sum Frequency Generation Studies of Carbon Dioxide Reduction on Gold: Effects of Electric Fields and Electrolyte Cations. — •Spencer Wallentine1, Quansong Zhu1, Savini Bandaranyake1, Somnath Biswas2, and Robert Baker1 — 1Ohio State University, Columbus Ohio, USA. — 2Princeton University, Princeton New Jersey, USA
The electrochemical interface is complex in function yet elegant in its ability perform redox processes. These processes are sensitive to the electrolyte cation during carbon dioxide reduction, however the reason for this remains the subject of debate. Using vibrational sum frequency generation we measure in-situ spectra of adsorbed carbon monoxide on polycrystalline gold during carbon dioxide reduction. The surface bound carbon monoxide redshifts with applied potential due to the Stark effect. From this Stark shift we measure the interfacial electric field, which reaches a maximum of 35 MV/cm. We find that the interfacial electric field begins to saturate at -0.9 V vs SHE, and is indicative of the formation of a dense cation layer in the interfacial region. Interestingly, -0.9 V is coincident with the onset of high efficiency carbon monoxide production, which suggest that interfacial cations or the associated electric field enhance this faradaic process. These results are further corroborated by an increase in the Tafel slope, which is predicted to occur as the active site density decreases due to site blocking by ions. Taken together we obtain a atomistic picture of the electrode electrolyte interface where ions block some of the active sites, but the remaining sites are more active due to electric field stabilization.