Upcycling photovoltaic silver waste into hierarchically structured electrocatalysts for flooding-resistant zero-gap CO2-to-CO electrolysis

Electrochemical CO 2 reduction reaction (CO 2 RR) offers a highly sustainable pathway for converting carbon emissions into valuable chemicals; however, developing robust catalysts from secondary resources that can withstand electrolyte flooding in zero-gap membrane electrode assemblies (MEAs) remain a significant challenge. Herein, we demonstrate a practical strategy by upcycling high-purity (~99.9%) silver nanoparticles (EoL-Ag NPs) reclaimed from end-of-life silicon solar panels into durable electrocatalysts for high-rate CO production. The EoL-Ag NPs, synthesized via a scalable laser-assisted photoreduction process following selective hydrometallurgical impurity extraction, exhibit an exceptionally pristine metallic state (Ag 0 ). Crucially, this upcycling route naturally imparts a multi-scale, polydisperse nano-to-micro morphology to the EoL-Ag NPs. This structural roughness establishes a robust hydrophobic microenvironment within the gas diffusion electrode, lowering the water adhesive force by 2.7-fold and enhancing localized affinity for gaseous CO 2 . Evaluated in a 10 cm 2 zero-gap MEA electrolyzer, the EoL-Ag catalyst outlasts conventional commercial counterparts, delivering a maximum CO partial current density of 296 mA cm −2 at a total current density of 400 mA cm −2 . Most importantly, the flooding-resistant electrode exhibits unprecedented stability, operating continuously for over 600 h at 100 mA cm −2 and for 55 h at an industrially demanding 200 mA cm −2 with a stable CO Faradaic efficiency of ~95%. This work proves that upcycled solar waste can serve as a highly durable alternative to commercial noble catalysts, simultaneously resolving PV waste accumulation and advancing scalable carbon utilization.