High-flux nickel foam electrodes with asymmetric binder engineering for efficient electrolyte transport and CO2 regeneration in reactive carbon capture

Abstract

Reactive carbon capture (RCC) from bicarbonate solutions offers a highly efficient pathway for carbon-neutral fuel production by bypassing energy-intensive CO₂ desorption steps. However, conventional carbon paper (CP)-based electrodes suffer from electrolyte flooding and limited mass transport in liquid-fed RCC systems, hindering in-situ CO₂ regeneration from bicarbonate. Here, we report a macroporous nickel foam (NF)-based electrode incorporating an asymmetric binder strategy that incorporates hydrophobic polytetrafluoroethylene (PTFE) in the microporous layer (MPL) and proton-conducting Nafion in the catalyst layer (CL). The macroporosity of NF and asymmetric binder architecture decouples bulk electrolyte transport from interfacial CO₂ regeneration. This asymmetric architecture effectively mitigates flooding and prevents excessive interfacial alkalization, facilitating rapid in-situ CO₂ regeneration from bicarbonate and ensuring a solid-liquid-gas triple phase boundary (TPB). The NF electrode achieves a CO Faradaic efficiency (FE) of 62.6% at 100 mA cm⁻² with a low cell voltage of 3.26 V in a bipolar membrane (BPM)-based membrane electrode assembly (MEA)-type electrolyzer. Furthermore, the electrode exhibits robust durability, maintaining stable continuous operation for 44 h. This structural engineering approach offers an effective and scalable strategy for overcoming mass transport limitations in RCC systems.