Abstract
Electrolysers offer an appealing technology for converting CO2 into high-value chemicals, but there are few tools available to track the reactions that occur inside operating electrolysers. Here, we report an electrolysis optical coherence tomography platform that visualizes chemical reactions occurring in a CO2 electrolyser with three-dimensional imaging and high spatial and temporal resolution. We recorded 12 h of footage from an electrolyser containing a porous electrode separated by a membrane, converting a continuous feed of liquid KHCO3 to CO at applied current densities of 50–800 mA cm–2. This platform visualized reactants, intermediates, and products, and captured the dynamic movement of cathode and membrane components during electrolysis. It also linked CO production to regions where CO2 was in direct contact with both membrane and catalyst layers, highlighting how this platform can be used to track reactions in continuous-flow electrochemical reactors.