Boron-doped diamond nanofilm on a Ti substrate possessing fast charge transfer: Strategy toward cost-effective electrochemical oxidation of refractory organic pollutants

This study suggests a breakthrough toward the high-cost issue of electrochemical degradation of refractory organic pollutants caused by adopting a boron-doped diamond (BDD) electrode. Specifically, effect of charge transfer capability of the BDD electrode on electrochemical oxidation of 4-chlorophenol (4-CP) and perfluorooctanoic acid (PFOA) is explored. Thin BDD nanofilm (thickness of ~400 nm) on a Ti substrate (BDD@Ti) was prepared to overcome the delamination of the BDD on the Ti via hot-filament chemical vapor deposition under optimum conditions. When compared with a commercial electrode (C-BDD, micron BDD film on a Nb substrate), inevitable metal-carbide layer formed at interface between BDD film and metal substrate is much thinner than that of C-BDD. The unique structural features of BDD@Ti facilitate a much faster charge transfer and degradation of both 4-CP and PFOA than C-BDD, which is attributed to shortening of electron pathway from surface to conductive substrate.