Growth Rate and Electrochemical Properties of Boron-Doped Diamond Films Prepared by Hot-Filament Chemical Vapor Deposition Methods

Boron-doped diamond (BDD) films have good electrochemical performance with a wide potential window and chemical stability in aqueous solutions, compared with other electrode materials made of Pt, glassy carbon, and so forth. BDD electrodes have been investigated for various industrial applications, such as ozone-dissolved water and effluent water treatment. In this study, to achieve a high synthesis rate of BDD films, trimethyl borate was additionally introduced to a hot-filament chemical vapor deposition (HF-CVD) system as a reactant gas. It was found that the growth rate and quality of diamond prepared using the HF-CVD system depended on the effect of CH 4 concentration on hydrogen, distance from filament to substrate, and supply B/C ratios. BDD films with a high growth rate in the range from 2 to 4 mu m/h have been obtained at a filament-to-substrate distance of 5 mm, a CH4 concentration of 4%, and B/C ratios of 0.3-2.0%. Cyclic voltammograms of a Pt and BDD electrodes in 0.2 M KNO3 have been investigated in terms of the effect of supply B/C ratios of 0.3, 0.5, and 2.0%. It was found that BDD electrodes had a wide potential window and a low background current compared with conventional Pt electrodes. The BDD films prepared and characterized in this study are efficient as electrodes for environmental applications.