Preparation And Electrocatalytic Decolorization Performance Of Ti/Sb-SnO₂ Electrode Material

With the development of chemical industry and rapid urbanization,water environmental pollution has been an arising challenge faced by the countries around the world.Due to its high catalytic activity and strong oxidation,electrocatalytic oxidation technology as one of the water treatment methods,has arisen wide concern.The selection of electrode materials is the key part of electrocatalytic oxidation technology.Ti/Sb-SnO₂ electrodes are now broadly well received by researchers owing to their high oxygen evolution potential,high generation of hydroxyl radicals and good electrocatalytical properties.Hence,it is of practical significance to prepare efficient and stable Ti/Sb-SnO₂ electrodes.In this paper,Ti/Sb-SnO₂ electrodes were mainly prepared by electrodeposition in colloid and organic systems.Then,the Ti/Sb-SnO₂ electrodes doped with titanium nitride?TiN?nanoparticles were prepared by dip coating method.By exploring the electrode structure and electrochemical performances,the effects of different experimental conditions on the performances of the electrodes were revealed.The study aimed to lay a solid foundation for improving the performance of Ti/Sb-SnO₂electrodes and their application in water treatment.Taking Sn-Sb colloid prepared as the medium of electrodeposition,Ti/Sb-SnO₂electrodes were prepared using a direct current electrodeposition method.The accelerated life and the decolorization efficiency of methyl orange for the electrodes were set as the main indexes of evaluating electrode performances.According to the results of the structure characterization and electrochemical test of electrodes,the optimal conditions for preparing the electrodes were determined to consist of:a doping 9%of Sb,current density of 5 m A cm^-2 and calcination temperature at 600?.As the metal inorganic salt happened to be hydrolyzed and condensation reaction in the preparation of colloid,the colloid contained high metal content,which further promoted active substance content of coating.As the tartaric acid of electrolyte could stabilize the presence of colloid,its complexation was able to greatly improve the properties of the coating to further gain fine active coating.The surface of the electrodes prepared in the colloid system exhibited compacter structure,which was conducive to enhancing the stability and electrocatalytic performances of the electrodes.Under the optimal conditions,the methyl orange decolorization rate of the electrode within 2 h reached 94.74%.A pulse electrodeposition method was used to modify the Ti/Sb-SnO₂ electrodes prepared in the colloid system.The pulsed turn on and turn off time were 1 ms and199 ms,respectively.The pulse electrodeposition method could overcome the defects including the slow diffusion speed and concentration polarization of macromolecular colloidal particles.Moreover,this method was capable of accelerating the nucleation rate of crystals and changing the growth direction of crystals in electrodeposition,as well as significantly improving the properties of the active layer for the electrodes.The X-ray photoelectron spectroscopy?XPS?analysis showed that electrodeposition method could exert great influence the active substances on the surface of the electrodes,while the electrodes made using pulse electrodeposition had high O_ads content,which enabled the electrodes having high electrochemical activity.Moreover,the modified electrodes using pulse electrodeposition could complete the decolorization of methyl orange within 2 h,and the accelerated life was 3.73 times of that using direct current electrodeposition techniques.In addition,the CNT interlayer was prepared using electrophoretic deposition to obtain Ti/CNT/Sb-SnO₂ electrodes.The interlayer introduced could increase voltammetric charges and electrochemical porosity,while the adsorption capacity and decolorization efficiency of methyl orange were enhanced.The Ti/Sb-SnO₂ electrodes were prepared by electrodeposition method in the dimethyl sulfoxide?DMSO?system.DMSO could overcome the shortfalls that the curling and cracking of coating resulted from high stress produced by hydrogen inclusion in aqueous solution when conducting electrodeposition to prepare Ti/Sb-SnO₂ electrodes.Moreover,it was able to highly dissolve metal salts.The electrolytic product of the solvent included in the deposited layer could promote the thinning and improvement of coating structure for SnO₂ crystals.Experimental results indicated that under the conditions comprising electrodeposition at 40?,calcination temperature at 600?and pulsed duty cycle of 20%,the accelerated life of the electrodes lived up to 97.84 h and the first order kinetic constant for the methyl orange decolorization reaction was 0.06738 min^-1,which suggesting electrodes presented a good decolorization performance on methyl orange.The prepared Ti/Sb-SnO₂-TiN electrodes doped with TiN nanoparticles using a dip coating method were applied in electrochemical decolorization of Orange II.The analysis results of scanning electron microscope?SEM?and X-ray diffraction?XRD?showed that the high surface activity of nano-sized TiN could endow the electrodes with compact,crack-free structure,and refine the grain size;based on the analysis of Transmission electron microscopy?TEM?and X-ray photoelectron spectroscopy?XPS?,it was obtained that TiN particles were shown to distribute on the surface of the electrodes,and effectively increased the content of O_ads in the electrodes;electrochemical tests indicated that the electrodes doped with TiN exhibited higher electrochemical activity and longer accelerated life.Besides,the electrodes presented a great electrochemical decolorization rate to Orange II,while its reaction rate constant was 8.7 times bigger than that of using the same method without dopping TiN.