Zero-Gap Bipolar Membrane Electrolyzer for Carbon Dioxide Reduction Using Acid-Tolerant Molecular Electrocatalysts

[Image: see text] The scaling-up of electrochemical CO(2) reduction requires circumventing the CO(2) loss as carbonates under alkaline conditions. Zero-gap cell configurations with a reverse-bias bipolar membrane (BPM) represent a possible solution, but the catalyst layer in direct contact with the acidic environment of a BPM usually leads to H(2) evolution dominating. Here we show that using acid-tolerant Ni molecular electrocatalysts selective (>60%) CO(2) reduction can be achieved in a zero-gap BPM device using a pure water and CO(2) feed. At a higher current density (100 mA cm(–2)), CO selectivity decreases, but was still >30%, due to reversible product inhibition. This study demonstrates the importance of developing acid-tolerant catalysts for use in large-scale CO(2) reduction devices.