Electrochemical Reduction of CO2 in Water‐Based Electrolytes KHCO3 and K2SO4 Using Boron Doped Diamond Electrodes

The performance of Boron Doped Diamond (BDD) electrodes for the electrochemical reduction of CO2 at room temperature and in water‐based electrolytes was investigated. Techniques such as linear sweep voltammetry, chronoamperometry, and chronopotentiometry were used to confirm the activity of BDD for the CO2 reduction. Besides H2, CO and HCOOH were found as major products with CH3OH as a minor product. The effect of anionic species with and without buffer capacity was investigated using KHCO3 and K2SO4 as electrolytes. BDD did not show any degradation after using it in several experiments. The Faradaic efficiency (FE) for CO in the gas phase and the concentration of HCOOH in the liquid phase were higher in K2SO4 than in KHCO3. However, the total FE for C1 products was lower than 20%. Then BDD electrodes were modified with silver, which improved the FE for CO to 68% in K2SO4 at −1.8 V vs. Ag/AgCl. Galvanostatic experiments were also performed for 10 hours at −10 mA cm−2 producing 30% FE for CO in the gas phase and 43,9 mM HCOOH in the liquid phase. Boron Doped Diamond electrodes are investigated as electro‐catalysts for the CO2 reduction in aqueous electrolytes using techniques such as linear sweep voltammetry, chronoamperometry, and chronopotentiometry. Besides H2, products such as CO, HCOOH and CH3OH were found. The effect of anionic species with and without buffer capacity using KHCO3 and K2SO4 as electrolytes is investigated, as well as, the modification of Boron Doped Diamond with silver improving the Faradaic efficiency for CO.