# Carbon Efficient CO2 Interfaces in Acid through Ion Management Channels

## TL;DR

This paper introduces ion management channels to improve CO2 electroreduction in acidic conditions by enhancing carbon efficiency and reducing hydrogen evolution.

## Contribution

The novel ion management channels combine cation- and anion-exchange domains to control ion transport and improve CO2 electroreduction performance.

## Key findings

- IMC-functionalized electrodes achieved ∼80% Faradaic efficiency for C2+ products at 0.5 A·cm–2.
- Single-pass carbon utilization of ∼90% was sustained over 70 h of pulsed operation.
- IMCs improved peak C2+ partial current density by 39% over monopolar cation-exchange ionomers.

## Abstract

CO2 electroreduction
(CO2E) in acidic media
enables high carbon utilization but is often limited by enhanced hydrogen
evolution (HER). Cation-exchange ionomer coatings can suppress HER
by enriching alkali cations at the catalyst surface, yet in
situ SERS reveals that they also cause excessive *OH adsorption,
hindering CO2 access and suppressing C–C coupling.
To address this, we introduce ion management channels (IMCs), a spatially
distributed ionomer architecture combining cation- and anion-exchange
domains to modulate nanoscale ion transport. Applied to PTFE-Cu gas
diffusion electrodes, IMCs facilitate the removal of excess *OH by
restructuring interfacial water, increasing *CO coverage, and enhancing
multicarbon (C2+) selectivity. IMC-functionalized electrodes
achieve ∼80% Faradaic efficiency for C2+ products
at 0.5 A·cm–2, with ∼90% single-pass
carbon utilization sustained over 70 h of pulsed operation. This represents
a 39% improvement in peak C2+ partial current density over
monopolar cation-exchange ionomers and a ∼3.4-fold enhancement
relative to bare Cu, highlighting the importance of ion-transport
engineering for efficient CO2E.