Suppressing Carbon Losses to 5% in Alkaline CO 2 Electrocatalysis Using Gold‐Decorated CuO Nanoneedle Catalysts With Modified Microenvironment

Abstract

Alkaline CO 2 electrolysis can reach industrially relevant rates, but it typically incurs substantial carbon losses through carbonate formation, limiting conversion efficiency. In this study, we show that combining a gold‐decorated CuO nanoneedle catalyst (N‑CuAu) with dynamic pulsed electrocatalysis and a synthetic electrolyte with tuned bulk hydroxide concentration ([OH − ]‐Bulk) suppresses carbonation while maintaining high overall performance in an alkaline electrolyzer. The integrated strategy reduces carbon losses to 5.7%, while achieving a single‐pass CO 2 conversion of 51% and an overall Faradaic efficiency (FE) of 92% for selective CO 2 reduction. The resulting carbonate formation ratio is about 182‐fold lower than conventional alkaline CO 2 electrolysis and 27 fold lower than state‐of‐the‐art neutral media CO 2 electrolysis. Using complementary in situ and ex situ characterizations, we identify an operative semi‐quantitative local alkalinity ([OH − ]‐Local) of 0.17 mol/Lit that correlates with suppressed carbonate formation and enhanced selectivity toward alcohol products, while confirming catalyst structural stability under dynamic pulsed operation. Together, these results establish hydroxide microenvironment control as a lever to reconcile high‐performance alkaline CO 2 electrolysis with low carbonation losses.