Secondary Alcohols as Rechargeable Electrofuels: Electrooxidation of 2-Propanol at Pt-Based Electrodes

BRUMMEL, OLAF; KHANIPOUR, PEYMAN; FROMM, L.; KATSOUNAROS, IOANNIS; LIBUDA, JÖRG; WAIDHAS, FABIAN; SIEVI, GABRIEL; GÖRLIG, A; MAYRHOFER, KARL J. J.; HASCHKE, S; MONTERO, MARÍA A.; BACHMANN, J.; WASSERSCHEID, PETER

Simposio; 1st Symposium on Chemical Bond Activation; 2019

Isopropanol (IPA) and its dehydrogenated counterpart acetone (ACE) can be used as a rechargeable electrofuel. IPA can be oxidized to ACE in a fuel cell and, subsequently, hydrogenated again catalytically. We investigated IPA oxidation on Pt single crystals, polycrystalline and nanostructured Pt electrodes, as well as on commercial Pt and PtRu catalysts. We used electrochemical infrared reflection absorption spectroscopy (EC-IRRAS) in combination with density functional theory (DFT), cyclic voltammetry (CV), and electrochemical real-time mass spectrometry (EC-RTMS).On Pt electrodes, the onset for IPA oxidation is observed at 0.3 VRHE, where ACE is formed at the Pt electrodes with high selectivity. The only side reaction observed is the formation of small amounts of CO2. The total oxidation to CO2 competes with the ACE formation but is efficiently suppressed as long as IPA is present. However, the ACE formed adsorbs strongly on the Pt electrodes and poisons the catalyst. This poisoning by adsorbed ACE is the limiting factor for the oxidation of IPA using Pt electrodes. By using PtRu alloy catalysts, the onset potential is shifted down to 0.1 VRHE and the poisoning can be reduced.