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Abstract Achieving high product selectivity at ampere‐level current densities is essential for the industrial application of electrochemical CO 2 reduction. However, the operational stability of CO 2 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 2 ) 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 TiB 2 ‐supported Cu surface, thereby reducing the energy barrier for C−C coupling. When coupling the CO 2 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 CO 2 conversion at ampere‐level current density and paves the way for integrating biomolecules conversion in stack‐level devices.
Lu et al. (Wed,) studied this question.