Rapid Product Analysis for the Electroreduction of CO2 on Heterogeneous and Homogeneous Catalysts Using a Rotating Ring Detector

Here, we demonstrate that small molecules such as H-2, CO, HCOO- and their mixtures, generated from the electroreduction of CO2 (CO2 RR), can be detected and quantified on a rotating ring-disc electrode (RRDE). We describe a series of systematic calibration protocol to quantify CO2RR products on four model electrocatalysts (Pt, Au, Sn, [Ni-II(cyclam)](2+)). In an RRDE assembly, products generated at the disc are convectively transported and detected at the ring detector before diffusing into the bulk solution, circumventing the need for product pre-concentration. As the electrochemical fingerprints of these small molecules and their mixtures on the Pt detector are unique, RRDE also excludes the need for separation. Thus, using the rotating ring detector significantly minimizes the time delay between product generation and detection compared to conventional techniques such as GC, LC and NMR. An RRDE allows faster screening of catalysts that can help accelerate catalyst discovery for CO2RR. It also enables time-dependent mechanistic studies of CO2RR catalysis. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.