(521ab) Investigating Corrosion Dynamics during CO2 Reduction Using Inductively-Coupled Plasma Mass Spectrometry

The electrochemical CO₂ reduction reaction (CO₂RR) provides a path towards sustainable production of carbon-based fuels and chemicals, using renewable electricity to drive the conversion of CO₂ into products such as ethylene, ethanol, and methane. Cu is a particularly interesting catalyst, as it can form C₂₊ products. A challenge limiting the implementation of CO₂RR is catalyst stability during reduction, and greater fundamental understanding is needed to uncover the governing physical and chemical factors, as well as degradation mechanisms, in CO₂RR operating conditions. The changing morphology of Cu during CO₂RR operating conditions can vary the product distribution.

The goal of this research was to quantify the dynamic corrosion of Cu CO₂RR electrocatalysts. We hypothesized that in CO₂RR conditions, the amount of degradation would be dependent on the applied potential and current. Cu electrocatalyst degradation in CO₂RR conditions was examined in varying gas environments to isolate the effects of hydrogen evolution and CO₂RR and potentiostatic and galvanostatic conditions in Faradaic and non-Faradaic regions to determine the effect of catalysis. Atomic force microscopy (AFM) was used to characterize the electrode surface pre- and post- electrolysis by distinguishing nanostructures on the electrode surface and calculating surface roughness, which was found to be dependent on applied potential. While AFM allowed for examination of the resulting morphology of electrode surfaces due to various experimental conditions, the use of inductively coupled plasma mass spectrometry (ICP-MS) enabled on-line studies for quantifying catalyst degradation. Using a flow cell allowed for simultaneously applying a potential while sending electrolyte effluent to the ICP-MS to detect corroded catalyst species in trace amounts (low ppb level). The use of on-line ICP-MS studies accelerates corrosion studies by enabling real-time measurements during reaction conditions. Elucidating the factors that drive catalyst degradation enables the assessment of the lifetime and long-term stability of electrocatalytic devices.