Preparation And Electrochemical Oxidation Performance Of Foam Ceramic-based Boron Doped Diamond Electrode

The boron-doped diamond（BDD）electrode with foam structure has the advantages of large specific surface area and high mass transfer rate,and has a great improvement in degradation efficiency compared with the plate-structured BDD electrode.However,the commonly used foam metal matrix has the disadvantages of high thermal expansion coefficient and easy to be corroded in electrochemical oxidation process.In this paper,the applicability of foam ceramics with low thermal expansion coefficient and high corrosion resistance as BDD electrode substrate was studied,as long as the electrochemical oxidation performance of foam ceramic-based BDD electrodes.（1）BDD films were prepared by hot filament chemical vapor deposition technology on the surface of foam Zr O₂,foam Si C and plate single crystal Si.The surface microstructure and film bonding properties of BDD electrodes based on two kinds of ceramic foam materials were compared.Meanwhile,the electrochemical properties of BDD electrodes based on foam ceramics were characterized by comparison with plate Si based BDD electrode.The results show that the BDD film deposited on the surface of foam Zr O₂ substrate exhibits better film-base bonding performance,with larger electrochemical active area（22.9 times of that of plate BDD electrode）,lower electron transfer resistance（0.2Ω）and film resistance（0.3Ω）.（2）The electrochemical oxidation performance of foam Zr O₂-BDD electrode and plate Si-BDD electrode was compared.The UV-Vis spectral characteristics of methylene blue on the two electrodes and the effect of stirring speed on its degradation efficiency were studied.Meanwhile,the direct and indirect oxidation process of methylene blue in the foam Zr O₂-BDD electrode system was analyzed.The results show that the foam Zr O₂-BDD electrode shows higher organic mineralization rate,reaction rate constant and current efficiency,and its energy consumption is the lowest,only 0.63 k Wh g^-1.The degradation efficiency of foam Zr O₂-BDD electrode was enhanced by increasing the stirring speed.Methylene blue can be directly oxidized on the surface of the foam electrode,which is controlled by mass transfer.The indirect oxidation process is realized by hydroxyl radical,and the effect ratio is about 65%.