High-yield electrochemical production of formaldehyde from CO₂ and seawater

The catalytic, electrocatalytic, or photocatalytic conversion of CO ₂ into useful chemicals in high yield for industrial applications has so far proven difficult. Herein, we present our work on the electrochemical reduction of CO₂ in seawater using a boron-doped diamond (BDD) electrode under ambient conditions to produce formaldehyde. This method overcomes the usual limitation of the low yield of higher-order products, and also reduces the generation of H₂. In comparison with other electrode materials, BDD electrodes have a wide potential window and high electrochemical stability, and, moreover, exhibit very high Faradaic efficiency (74 %) for the production of formaldehyde, using either methanol, aqueous NaCl, or seawater as the electrolyte. The high Faradaic efficiency is attributed to the sp ³-bonded carbon of the BDD. Our results have wide ranging implications for the efficient and cost-effective conversion of CO₂. Boron is a diamond's best friend: A boron-doped diamond (BDD) electrode exhibited very high Faradaic efficiency (74 %) for the production of formaldehyde using either methanol, aqueous NaCl, or seawater as the electrolyte at room temperature and ambient pressure.