Electrooxidation of 2-Propanol on Mono- and Bi-Metallic Noble Metal Nanoparticles in Alkaline Studied with Real-Time Product and Dissolution Characterization

Abstract

The selective electrochemical oxidation of 2-propanol to acetone can be used in fuel cells to deliver low-carbon electricity and efficiently utilize hydrogen that is stored in liquid organic hydrogen carrier molecules. Here we study the electrooxidation of 2-propanol in alkaline electrolyte, on various commercially available carbon-supported mono- and bi-metallic noble metal nanoparticles. We use voltammetry to compare the activity of different catalysts, and we combine a flow cell with real-time analytics to monitor the products of the reaction and the dissolution of metal atoms in the presence and absence of 2-propanol. While acetone if formed on all catalysts, our results show that the onset potential is the lowest for PtRu/C, Rh/C and PdRh/C, but the oxidation current for the latter reaches a much higher value before the surface is passivated, suggesting that PdRh/C would be preferred in an alkaline fuel cell that is fed with 2-propanol. Online dissolution monitoring suggests that the anode in a 2-propanol fuel cell should not be exposed to potentials above ca. +0.8 V during transient operation, i. e., during startup/shutdown conditions, to prevent dissolution of palladium and rhodium from the catalyst surface.