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

Abstract

Among various products from electrocatalytic CO2 reduction (CO2ER), 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 CO2ER with 5‐hydroxymethylfurfural oxidation reaction (HMFOR). A BiOCl–CuO catalyst was designed to sustain CO2ER to HCOOH at partial current density of 500 mA/cm2 with FEHCOOH above 90% and 700 mA/cm2 with FEHCOOH 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 CO2ER process, and the presence of CuO will promote this transformation which are supported by DFT calculations. Coupling HMFOR with CO2ER, we realize both FEHCOOH and FEFDCA above 95% simultaneously, providing new prospects vista for the electrosynthesis of value‐added products from paired system.