Coupling electrochemical CO2 reduction to syngas with chloride-mediated dye degradation to CO2 in a one-compartment cell

Abstract

The development of the electrochemical carbon dioxide reduction reaction (CO₂RR) via renewable electricity is hindered by the low efficiency of the anodic oxygen evolution reaction (OER). Herein, we design an integrated cell that replaces the anodic reaction with dye degradation and can simultaneously realize the degradation of MO to CO₂ and CO₂ electrochemical reduction in a one-compartment cell. For the anodic reaction, chloride ions can be oxidized to HClO and trigger the full degradation of 100 mg L⁻¹ MO within one hour at 6 mA cm⁻². The anodically produced CO₂ is left in the electrolytic cell, which can partially supplement the cathodic consumption of external CO₂. In a pollutant-rich environment, the chloride ions can also effectively maintain the CO₂RR efficiency of the Ag catalyst, achieving a syngas ratio of CO : H₂ from 4 : 1 to 2 : 3 at different pollutant concentrations. This integrated experimental design may thus serve as a framework for the design of the CO₂RR and waste degradation with high economic viability.