Zero-gap bipolar membrane electrolyzer for carbon dioxide reduction using acid-tolerant molecular electrocatalysts

Abstract

The scaling-up of electrochemical CO2 reduction requires circumventing the CO2 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 H2 evolution dominating. Here we show that using acid-tolerant Ni molecular electrocatalysts selective (> 60%) CO2 reduction can be achieved in a zero-gap BPM device using a pure water and CO2 feed. At higher current density (100 mA cm-2), CO selectivity de-creases, but was still >30%, due to reversible product inhibition. This study demonstrates the importance of developing acid-tolerant catalysts for use in large-scale CO2 reduction devices.

A Bipolar Membrane-Integrated Electrochlorination Process for Highly Efficient Ammonium Removal in Mature Landfill Leachate: The Importance of ClO• Generation

“…In addition to its emerging applications in CO 2 reduction, 18,19 water electrolysis, 17 and fuel cells, 31 the findings of the current study can broaden the domain of environmental applications of the BPM when it is integrated into an electrochemical system. In contrast with reports on the coupling of BPMs and monopolar membranes for separation and recovery of ammonium in heavily concentrated solutions (e.g., urine), 22,59 our concept is a transformation process rather than a transfer process, which is especially suited for treating medium-concentration ammonium-containing wastewater with the purpose of completely eliminating nitrogen pollution.…”