Preparation Of Palladium-Conducting Polymer-Nickel Foam Electrodes And Electrocatalytic Reductive Dechlorination Of Chlorophenols

Environmental effect and effective removal of chlorinated organic compounds have attracted many attentions due to its strong toxicity, widespread, and easy accumulation and migration in the food chain, as well as serious effect on human secretion system. Among the many methods, electrocatalysis was received many emphasis due to the high efficiency and non-pollution. In addition, Pd decorated electrode exhibited huge advantages and promising application in the research field of catalysis and hydrogenation. On the basis of the research at home and abroad, three kinds of composite electrodes such as Pd/Ni, Pd/PANI/Ni and Pd/PPY/Ni were prepared. The structures and physicochemical properties were investigated by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). In addition, dechlorination activities together with the dechlorination mechanism of the modified composite electrodes were proposed.Pd/Ni electrodes were prepared through galvanostatic method. Subsequently, the apparent morphologies, crystal structures and surface state of Pd/Ni electrodes prepared from different conditions were investigated by many techniques. Meanwhile, electrocatalytic dechlorination activity for monochlorphenol, dynamic characteristic and stability of the as-prepared Pd/Ni electrodes were mainly investigated. It was found that Pd particles existed in the form of dendritic structure and zero state, which exhibited excellent chemical-stability and dechlorination activity. Furthermore, the reactions fitted well with the first order kinetics function.Pd/PAIN/Ni composite electrodes were synthesized by electrochemical deposition method. Pysicochemical properties such as apparent morphologies, crystal structures and surface states were characterized through scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The effect of polymerization conditions on morphologies, structures and dechlorination activity for dichlorophen of Pd/PAIN/Ni composite electrodes were mainly studied. All results indicated that PPYs in the Pd/PANI/Ni composite electrode existed in the form of needle-shaped, while nulvalent Pd particles dispersed well as clusters in the network on PPYs, in which the optimal polymerization conditions were obtained with the polymerization current of24mA, temperature of0℃and time of20min, respectively.Pd/PPY/Ni composite electrodes were constructed through constant current cathodic electrodeposition. The apparent morphologies, crystal structures and surface states were studied by related techniques. Furthermore, the effect of polymerization conditions on morphologies, structures and dechlorination activity for dichlorophen was mainly investigated. Results showed that the dopant ions, applied potential, polymerization temperature and time exhibited significant influences on the apparent morphology and distribution of PPYs microspheres. Furthermore, as the polymerization process was continued20min under0.6V at0℃in the presence of toluenesulfonic acid, the minimum particle sizes and uniform distributions of PPYs microspheres were obtained, which provided a favorable condition for the crystallize and growth of Pd particle.The stability of Pd/PPY/Ni composite electrodes was investigated. In addition, the dechlorination activity for dichlorophen and its isomerides and dynamic characteristics were studied. It was found that Pd/PPY/Ni composite electrodes displayed excellent electrochemical reductive dechlorination activity. Besides, under120min, the dechlorination activity for2,4-dichlorophenol was91.1%, while3,5-chlorophenol was68%.