High-performance gas diffusion electrodes for next-generation CO₂ conversion technologies

The development of CO₂ utilization technologies has seen rapid progress during the past few years. In this area of research, electrochemical CO₂ reduction (eCO₂R) has been identified as one of the promising pathways. However, this process is yet to reach industrially relevant rates of product formation. In the eCO₂R, the gas diffusion electrode (GDE) is the key component, with its architecture playing an important role. This review presents the latest advancements and opportunities in GDE structural design and materials selection, with a deep dive into the structure-performance relationship and its complex interplay in eCO₂R. Many recent research efforts have focused on improving catalysts, gas diffusion structures (gas diffusion layers (GDLs) and porous hollow fiber walls), electrolytes, and interfaces in order to optimize key performance metrics such as activity, selectivity, and stability, which are often intertwined and can complicate design efforts. The basic configuration has transitioned from conventional planar GDEs to self-supported hollow fiber GDEs (HFGDEs), along with emerging advanced forms of planar GDE, such as mesh, woven, carbon-free, and heteroarchitectural designs. These advancements have led to enhanced triple-phase boundary formation and improved mass transfer, resulting in high-performance GDEs capable of achieving ampere-level current densities (∼3 A cm^-2), high faradaic efficiencies (FE) for target products, and extended operational stability (>100 h). Further, we discuss current bottlenecks and provide perspectives aimed at offering new insights and guiding research directions to advance the development of industrially applicable GDE-based eCO₂R systems and facilitate their practical implementation.