Activity Trends for the Selective Oxidation of 2-Propanol to Acetone on Noble Metal Electrodes in Alkaline Electrolyte

Abstract

Fuel cells based on 2-propanol can be used to produce electricity utilizing the hydrogen stored in liquid organic hydrogen carriers. While the focus has previously been on acidic media, where only platinum-based electrodes are active, we explore here the oxidation of 2-propanol in alkaline solutions on different noble metal electrodes. Using experimental and computational methods, we find that the reaction is selective to acetone, whereas C–C bond breaking and the formation of adsorbed CO do not take place. The onset potential increases along the series Rh < Pt < Pd < Au, a trend that correlates with the adsorption energy of acetone on the respective surfaces. The oxidation rate decays under potentiostatic conditions due to the progressive accumulation of acetone at the surface. At high overpotentials, the reaction is limited by oxide formation. Given that alkaline systems are not restricted to exclusively platinum-based electrodes, a broader range of materials may be found that act as anodes for efficient 2-propanol fuel cells.

Mixed Potential Driven Self-Cleaning Strategy in Direct Isopropanol Fuel Cells

“…It demonstrates that other factors rather than double layer charging current are related to the current decline between each scan direction. Previous in situ vibrational studies have revealed that acetone strongly adsorbs on the Pt electrode surface when IPA oxidation progresses. ,− Moreover, the current density trend in the potential region overlaps with the trend of the mass signal for acetone determined by electrochemical mass spectroscopies, , indicating that the main product of IPA oxidation in the corresponding region is acetone. Based on the results, the acetone adsorbates poison the active sites on the electrode surface, leading to a decrease of the number of active sites.…”