High‐efficient electrocatalytic CO₂ reduction to HCOOH coupling with 5‐hydroxymethylfurfural oxidation using flow cell

Among various products from electrocatalytic CO 2 reduction (CO 2 ER), HCOOH is highly profitable one. However, the slow kinetics of anodic oxygen evolution reaction lowers overall energy efficiency, which can be replaced by an electro‐oxidation reaction with low thermodynamic potential and fast kinetics. Herein, we report an electrolysis system coupling CO 2 ER with 5‐hydroxymethylfurfural oxidation reaction (HMFOR). A BiOCl–CuO catalyst was designed to sustain CO 2 ER to HCOOH at partial current density of 500 mA/cm 2 with FE HCOOH above 90% and 700 mA/cm 2 with FE HCOOH above 80%. In situ and ex situ x‐ray absorption fine structure was used to capture the structure transform of BiOCl–CuO into metallic Bi and Cu during CO 2 ER process, and the presence of CuO will promote this transformation which are supported by DFT calculations. Coupling HMFOR with CO 2 ER, we realize both FE HCOOH and FE FDCA above 95% simultaneously, providing new prospects vista for the electrosynthesis of value‐added products from paired system.