In Situ Mapping of Aqueous CO2 during the Electrochemical CO2 Reduction Reaction
Year: 2026
Type: preprint
Abstract: Electrochemical interfaces feature dynamically evolving local reactant distributions that strongly influence catalytic behavior. In electrochemical CO 2 reduction (CO 2 RR), the low solubility and limited diffusion of CO 2 generate highly non-uniform local reaction environments near electrochemical interfaces. However, the actual spatial distribution of dissolved CO 2 within the interfacial structure under operating conditions remains poorly understood due to limited experimental visualization methods that probe interfacial structure. Here, we introduce an in situ ratiometric fluorescent labeling strategy with a CO 2 -sensitive chemosensor to directly visualize dissolved CO 2 distributions during CO 2 RR. Using a pyrene-modified fluorescent chemosensor, we directly visualize the spatial distribution and dynamic evolution of local dissolved CO 2 concentrations near electrochemical interfaces. The measurements reveal pronounced spatial heterogeneity in the CO 2 RR microenvironment, dynamic evolution of gas-liquid-solid interfaces, and unexpectedly strong local CO 2 enrichment. Dissolved CO 2 concentrations near the interface approached ~84.4 ± 27.5 mM. Beyond CO 2 RR, this work establishes fluorescent labeling as a general operando visualization strategy for probing local reactant distributions and interfacial mass transport processes in electrochemical systems.
Source: ChemRxiv
Institution: National University of Singapore
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223133146