A Comprehensive Approach to Investigate CO₂ Reduction Electrocatalysts at High Current Densities

ConspectusAs electrochemical CO2 reduction studies progress from beaker or H-cell devices operating at low current densities to gas diffusion electrode (GDE)-based that sustain high reaction rates and provide an avenue toward commercialization, the overall system becomes significantly more complex. While may vary for different approaches, it is essential maintain same scientific rigor when analyzing these systems. The mass transfer optimizations used in GDE based approaches necessarily add complexity new challenges need be analyzed overcome terms of both engineering as well analysis techniques. This Account puts into perspective our recent works density electrolysis performance via a comprehensive investigation entire system.In particular, we show importance monitoring (i) flow outlet cathodic compartment, (ii) anodic composition CO2/O2 ratio, (iii) pH variations electrolyte. A rigorous parameters allows us achieve complete carbon balance, addition accounting total 100% Faradaic efficiency. By cathode CO2:O2 demonstrate methods can self-validate results providing robustness. We this approach holds zero-gap membrane assembly device flowing-catholyte device. In addition, reveals having alkaline environment vicinity absorb substantial amounts CO2, which greatly distort efficiencies if not accounted for. rate reactor appears simple task, mixed gases small lab-scale reactors discuss various measure rates.While well-known play role activity selectivity reduction, operational initial electrolyte, there are long transients before steady state reached (on order hours), anolyte catholyte over duration electrolysis.By varying type (anion exchange, cation bipolar membrane), use quantitatively identify major differences related distinct types. conclusion complex processes entail thorough necessary accurately analyze devices.