Electrochemical reduction of CO2 on fluorine-modified boron-doped diamond electrode

Abstract Fluorine-containing diamond was deposited onto boron-doped diamond (BDD) substrate in the hot-filament chemical vapor deposition (HFCVD) process. The carbon source composed of acetone and trimethyl borate was mixed with hexafluoropropylene and then used to prepare a fluorine-modified BDD (F-BDD) film. X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurement were employed to characterize the film surface. Electrochemical reduction of CO2 was performed on the F-BDD electrode in a three-electrode cell in NaCl electrolyte. The Faradaic efficiency of formaldehyde (HCHO) generation on the electrode surface in CO2 reduction was measured and analyzed. The fluorinated surface decreased the adsorption of foreign species, stabilizing the F-BDD electrode. Scanning electron microscope (SEM) was used to observe the chemical contamination on the electrode surface in the reductive circumstance. In comparison with the substrate BDD electrode, the F-BDD electrode was found to be highly durable after a long reduction process because of its improved chemical stability and anti-contamination properties.