Heteroarchitectural Gas Diffusion Layer Promotes CO₂ Reduction Coupled with Biomass Oxidation at Ampere-Level Current...

Achieving high product selectivity at ampere-level current densities is essential for the industrial application of electrochemical CO₂ reduction. However, the operational stability of CO₂ electrolyzers at large current density has long been hindered by flooding of gas diffusion layer (GDL). Herein, a new heteroarchitectural GDL is designed to overcome flooding. Such GDL is constructed by sequentially sputtering the conductive silver and titanium boride (TiB₂) onto a polytetrafluoroethylene substrate. Assembled with Cu catalyst in a flow cell, a maximum ethylene Faradaic efficiency of 64.7 % was achieved at a current density of 1.2 A cm^-2 in 6 M KOH. Furthermore, the GDL is capable of stable operation for over 40 hours at 400 mA cm^-2. Theoretical calculations and in situ experiments demonstrate enhanced intermediates adsorption on the TiB₂-supported Cu surface, thereby reducing the energy barrier for C-C coupling. When coupling the CO₂ reduction reaction with 5-hydroxymethylfurfural oxidation reaction, Faradaic efficiencies of 49.2 % for ethylene and 85.4 % for 2,5-furandicarboxylic acid were achieved at 1.2 A cm^-2. This work provides a highly stable GDL for efficient CO₂ conversion at ampere-level current density and paves the way for integrating biomolecules conversion in stack-level devices.