Carbon dioxide reduction

In a global demand for a circular chemical economy, this study investigates the field of electrochemical carbon dioxide reduction, finding new ways to effectively convert waste carbon dioxide into valuable fuels and chemicals.

Electrochemical carbon dioxide reduction represent a pathway to achieve a circular chemical economy where fuels and chemicals can be synthesised from waste carbon dioxide.

A promising approach involves the use of a zero-gap electrolyser with the carbon dioxide (CO2) reduction catalyst loaded onto a gas-diffusion electrode (GDE) directly contacting a cation exchange membrane (CEM), bipolar membrane (BPM), or anion exchange membrane (AEM).

These zero-gap structures have been proposed as a route to high current densities and to reduce manufacturing costs. This is due to the catalyst being in close contact with the membrane allowing it to strongly influence the local environment of the catalyst.

When scaling up electrochemical CO2 reduction, it becomes crucial to address the issue of CO2 loss as carbonates under alkaline conditions. However, zero-gap cell structures with a reverse-bias bipolar membrane (BPM) offer a possible solution, although the catalyst layer in direct contact with the acidic environment of a BP usually leads to a domination of hydrogen.

Our findings

In this study, we demonstrate that by using acid-tolerant Ni molecular electrocatalysts, we can achieve a selective CO2 reduction of over 60% in a zero-gap BPM setup using pure water and CO2 feed. Even at higher densities, such as 100 mA cm–2, the carbon selectivity remains above 30%, although it may decrease due to reversible product inhibition.

This study demonstrates the importance of developing acid-tolerant catalysts, especially for large-scale CO2 utilisation efforts.

Colorful 3D Illustration Depicting the Process of Electrolysis in a Chemical Cell
Illustration depicting the process of electrolysis in a chemical cell.


Mark Forster, Francesca Greenwell, Preetam K. Sharma, Eileen H. Yu, and Alexander J. Cowan. J. Am. Chem. Soc. 2022, 144, 17, 7551–7556.