Enhanced H₂O₂ Production at Reductive Potentials from Oxidized Boron-Doped Ultrananocrystalline Diamond Electrodes

This work investigates the surface chemistry of H₂O₂ generation on a boron-doped ultrananocrystalline diamond (BD-UNCD) electrode. It is motivated by the need to efficiently disinfect liquid waste in resource constrained environments with limited electrical power. X-ray photoelectron spectroscopy was used to identify functional groups on the BD-UNCD electrode surfaces while the electrochemical potentials of generation for these functional groups were determined via cyclic voltammetry, chronocoulometry, and chronoamperometry. A colorimetric technique was employed to determine the concentration and current efficiency of H₂O₂ produced at different potentials. Results showed that preanodization of an as-grown BD-UNCD electrode can enhance the production of H₂O₂ in a strong acidic environment (pH 0.5) at reductive potentials. It is proposed that the electrogeneration of functional groups at oxidative potentials during preanodization allows for an increased current density during the successive electrolysis at reductive potentials that correlates to an enhanced production of H₂O₂. Through potential cycling methods, and by optimizing the applied potentials and duty cycle, the functional groups can be stabilized allowing continuous production of H₂O₂ more efficiently compared to static potential methods.