Preparation Of Aligned Carbon Nanotubes Electrode For Electrocatalytic Reduction Of Selected Organic Substances

Carbon Nanotubes(CNTs) are promising functional materials for their strongmechanism intensity, chemical capability and considerable adsorption. In order todevelop their application in environmental field, the multi-walled carbon nanotubes(MWCNTs) on different Ti, Ni, graphite substrates are prepared by chemical vapordeposition (CVD) with dimethylbenzene as carbon source and ferrocene as catalystand then they are purified in the HNO₃+H₂SO₄ solution in this study, respectively.The prepared electrodes are characterized by SEM, transmission electron microscopy(TEM), and X-ray diffraction (XRD). The results indicate that carbon nanotubes arewelled arrayed on the Ti substrate and their diameter is about 10nm to 30nm. TheFT-IR spectrum shows that the surface of multi-walled Carbon nanotubes containssome hydrophile groups such as -SO₃H, -C=O and -OH. The electric capability ofdifferent chemical vapor deposition time is detected by A.C impedance. Theconclusion is that the optimal deposition time is 5 min considering the mechanismintensity, stability and electric capability. The Pd is electrochemical deposited on thecarbon nanotubes at the 200 mV potential bias and then the Pd/MWCNTs/Ti electrodeis prepared for further use.It is known that the carbon nanotubes have excellent abilities of storing uphydrogen and electronic conduction. Therefore the Pd/MWCNTs/Ti electrode isapplied in the electrochemical reaction of hydrogenation in the field of environmentalpollution removal. The decolor efficiency of azo dye and the dechlorinationalefficiency of 2,4,5- polychlorinated biphenyl(2,4,5-PCB) are investigated usingH-type reactor with Pd/MWCNTs/Ti electrode as cathode. The results suggest that theapplication of Pd/MWCNTs/Ti in decoloring azo dye can achieve approving effectwith the decolor efficiency 77.2ï¼…at -0.8V voltage during 120 min electrochemicalreaction. The decolor efficiency is strongly influenced by the potential bias and the pHvalue of anodic electrolyte meanwhile the Pd/MWCNTs/Ti electrode is provided withgood stability in the reaction. On the other hand, the dechlorination of 2,4,5-PCB hasnot achieve satisfactory effect with its dechlorinational efficiency only 26.5ï¼…at -1.1V potential bias during 40 hours electrochemical reaction. Also, at the point ofenhancing transmission ability, an improved scheme is proposed in this study.In conclusion, chemical vapor deposition is an easily-operated and economicalprocess for synthesis multi-walled carbon nanotubes (MWCNTs). Furthermore, themulti-walled carbon nanotubes electrode has outstanding application value andpromising prospect in environmental field.