Investigations On Preparation And Electrochemical Properties Of Boron-doped CVD Diamond Films Electrode

Diamond is a multifunctional material in many applications because of its excellent properties in mechanical, thermal, optical, electrical and chemical inertness.Pure diamond film is an excellent insulating material with resistivity of more than 1010Ω·cm. Ion implantation or doping, however, can turn it into semiconductor or conductor by alter its conductive properties, which extend its application in many fields.Recently boron-doped diamond (BDD) thin film is drawing more and more attention of research workers for its excellent properties and many applications in electrochemistry. The result shows that heavily boron doped diamond thin film has good electrical conductivity and is an excellent electrode material.In this paper, BDD electrodes were prepared on Ti substrates (Ti/BDD) by microwave plasma CVD technique (MPCVD). B(OCH3)3 was the doped chemical. The effects of different parameters which include Ti substrates with different surface, the flow ratio of CH4 and the flow ratio of B(OCH3)3 on the morphology and the properties of BDD thin films were investigated by means of SEM, Raman and XRD. The result showed crystalline quality was better, the content of non-diamond phase least and the stress in the film less when BDD film was prepared on corundum sand-blasted Ti substrate with CH4 flow 3 sccm and B(OCH3)3 flow 8 sccm.The electrochemical performance of BDD electrodes were tested by electrochemical workstation. The results obtained are as follows: (a) Most samples possess a wide electrochemical window (up to 3.7 V vs. SCE) and a low background current close to zero, exhibiting good electrochemical properties. (b) The evolved oxygen potential decreased with the increase of the temperature. However, in an appropriate temperature range, the rise of temperature is beneficial to the electrode reaction and decreases the wastage of electric energy caused by the side reaction of oxygen evolution.The electrochemical oxidation of phenol on as-grown BDD electrodes has been carried out at elevated temperatures up to 80 oC. The degradation performance under different temperatures was investigated. There is an optimized temperature at 60 oC for achieving the highest oxidation efficiency. In present condition of experiment, 60 oC is the suitable reaction temperature, at which the COD removal rate reached 100% in 5 hours. It indicates that the temperature plays an important role in enhancing oxidation efficiency.