Differentiation between Carbon Corrosion and Oxygen Evolution Catalyzed by NixB/C Hybrid Electrocatalysts in Alkaline Solution using Differential Electrochemical Mass Spectrometry

Carbon is a frequently used electrode material and an important additive in catalyst films. Its corrosion is often reported during electrocatalysis at high anodic potentials, especially in acidic electrolyte. Investigation of the carbon corrosion in alkaline environment is difficult due to the CO 2 /CO 3 2- equilibrium. We report the on-line determination of electrolysis products generated on Ni x B/C hybrid electrocatalysts in alkaline electrolyte at anodic potentials using differential electrochemical mass spectrometry (DEMS). Ni x B/C catalyst films were obtained from mixtures containing different ratios of Ni x B and benzoxazine monomers followed by polymerization and pyrolysis. The impact of the composition of the electrocatalyst on the dominant electrolysis process allows to distinguish between the oxygen evolution reaction and carbon corrosion using DEMS results as well as the catalyst surface composition evaluated from X-ray photoelectron spectra. At the imposed highly oxidative conditions, an increasing amount of Ni x B in the electrocatalyst leads to a suppression of carbon corrosion. ; The authors are grateful for financial support from the Deutsche Forschungsgemeinschaft within the research unit FOR 2982 "UNODE - unusual anode reactions" [433304633 and 433304702] and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat [833408]). S. D. acknowledges financial support by the International Max-Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS-RECHARGE).