Electrochemical CO2 reduction properties of boron-doped diamond powder

The electrochemical CO2 reduction reaction (CO2RR) properties of boron-doped diamond powder (BDDP) were investigated. A BDDP-painted electrode was prepared by casting BDDP ink on the surface of a BDD thin-film electrode as a current collector. The CO2RR properties of the BDDP-painted electrode were compared to those of conventional BDD thin-film electrodes, which were prepared directly on a conductive silicon wafer substrate by the microwave plasma-assisted chemical vapor deposition method. The result of the electrolysis at -1.8 V vs. Ag/AgCl in 0.5 M KCl catholyte showed that the BDDP-painted electrode was superior to the BDD thin-film electrode because it produced a large amount of products (formic acid and carbon monoxide) at a low overpotential. The highest performance of the CO2RR in the BDDP-painted electrode was achieved with the BDDP with high boron doping and high sp2 carbon content. We considered that structural defects, boron doping level, and sp2 carbon content influenced the reactivity for CO2 reduction. Therefore, the BDDP-painted electrodes should be useful not only for the production of a large-size electrode but also for efficient CO2RR.