Preparation of a porous boron-doped diamond/Ta electrode for the electrocatalytic degradation of organic pollutants

Polycrystalline boron-doped diamond (BDD) was grown on a Ta substrate by electron-assisted hot filament chemical vapor deposition, and porous BDD/Ta multilayer films were constructed by Ni-nanoparticle-assisted plasma etching. The etching process and the formation mechanism of the porous nanostructure on the BDD were investigated by changing the Ni sputtering time and the BDD etching time. Under optimal etching conditions, differently shaped nanoholes appeared on the different crystal planes of the diamond crystallites, including square and triangular (or hexagonal) holes. In addition, changes in the elemental composition, crystal, and chemical-bonding structures were analyzed; the effective electroactive surface area and charge transfer capability at the liquid-solid interface were found to be improved in the etched crystallites. Therefore, we believe that the electrocatalytic performance of a porous BDD/Ta electrode would also be improved, as electrocatalytic performance is strongly affected by the porous nanostructures of BDD films. The porous BDD/Ta electrode acted as the anode for the rapid degradation of methylene blue through the electro-Fenton process. An etched BDD/Ta film with a nanoporous surface exhibits excellent electrocatalytic behavior. [Display omitted]