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

Achieving high product selectivity at ampere-level current densities is essential for the industrial application of electrochemical CO reduction. However, the operational stability of CO 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 (TiB) 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 in 6 M KOH. Furthermore, the GDL is capable of stable operation for over 40 hours at 400 mA cm. Theoretical calculations and in situ experiments demonstrate enhanced intermediates adsorption on the TiB-supported Cu surface, thereby reducing the energy barrier for C-C coupling. When coupling the CO 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. This work provides a highly stable GDL for efficient CO conversion at ampere-level current density and paves the way for integrating biomolecules conversion in stack-level devices.