Anode Reaction Control for a Single‐Compartment Electrochemical CO2 Reduction Reactor with a Surface‐Activated Diamond Cathode

The electrochemical reaction of carbon dioxide (CO2) in aqueous electrolyte solutions is attracting increasing attention for sustainable chemical production. Boron‐doped diamond (BDD) electrodes have been previously shown to be very effective for the stable electrochemical production of formic acid from CO2. Typically, the electrochemical production of formic acid by CO2 reduction (CO2R) reaction is performed with a dual‐compartment flow reactor equipped with a membrane separator. The problems caused by the membrane separator, such as scaling‐up, complicated operational control and materials costs can be solved using a membrane free single‐compartment reactor. Here we demonstrate anode reaction control for a single‐compartment CO2R flow reactor using a surface‐activated BDD cathode and achieve a Faradaic efficiency for formic acid production of over 70 %. We demonstrated anode reaction control for a membrane‐free single‐compartment carbon dioxide reduction (CO2R) flow reactor with a boron‐doped diamond (BDD) electrode. Fluorinated polymer coatings over an IrO2 electrode improved the selectivity of anode reactions. The use of a halogen free electrolyte and the activation of BDD cathode improved the CO2R reaction selectivity and achieved a Faradaic efficiency of formic acid of over 70 %.