Precipitation and binder effectiveness in the electrochemical reduction of CO2 at Cu electrocatalysts in zero-gap MEA cells

Document Type

Article

Publication Date

9-20-2025

Abstract

Membrane Electrode Assembly (MEA) electrolyzers equipped with Gas Diffusion Electrodes (GDEs) present significant potential for industrial-scale CO₂ reduction (CO2RR) due to their capability to operate at high current densities with high Faradaic efficiencies (FEs). Despite this advantage, several key challenges persist, including the long-term stability of MEAs, enhanced selectivity for CO2RR, and the effective production of multi-carbon products. This study addresses critical factors leading to the failure of Cu-based CO₂ electrolyzers, specifically suppression of the hydrogen evolution reaction, the loss of electrocatalytic activity in the Gas Diffusion Layer (GDL) caused by electrocatalyst degradation or agglomeration, and the formation of carbonate salts, all within the context of various electrocatalyst binders (or ionomers when functional groups are employed) combinations including Cu-PTFE, Cu-PVDF, and Cu-Nafion. Energy-dispersive X-ray spectroscopy (EDX) and Cu L-edge X-ray absorption spectroscopy (XAS) demonstrate that PTFE maintains the highest loading of electrocatalysts on the gas diffusion layer, indicating sustained active sites for CO2RR. Complementary carbon K-edge and potassium L-edge XAS reveal the presence of carbonates in K2CO3, KHCO3, and malachite forms. Combining the electrochemical results with soft X-ray absorption spectroscopy, we hypothesize that carbonate plays a dual role in CO2RR. First, the dissolution of Cu under reaction conditions encourages the formation of copper carbonate hydroxide, which enhances C2 product selectivity. Second, the precipitation of K2CO3 and KHCO3 salts fills the pores in GDE, promoting the hydrogen evolution reaction.

Publication Source (Journal or Book title)

Electrochimica Acta

This document is currently not available here.

Share

COinS