The Modification Of Ti/TiO₂NTs/PbO₂ Anode And Its Electrocatalytic Application Research

The electro-catalytic oxidation technology as an environment-friendly advanced oxidation technology attracts extensive attention duo to it possesses not only strongly catalytic activity in process,but exerts the advantages of environmental compatibility,little secondary pollution,high security and easy implementation.Thereinto,the selection of anode play essential importance role in process of the electro-catalytic activity.The PbO2 electrode with the low price,excellent corrosion resistance and high oxygen overpotential has been supposed as the one of potential anodic material.However,the activity and stability of the PbO2 needs to be improved as more as possible.Thus,we make a series of fundamental research in this paper to achieve the targets of improving the PbO2 activity and stability.The main contributions of this research are as follows:The Ti/TiO2NTs was employed as the substrate material.The NiO and Ce-doped PbO2 were sequentially loaded on the Ti/TiO2NTs substrate by combining with the pulse electrochemical deposition and high-temperature calcination method for preparing the Ti/TiO2NTs/NiO/Ce-PbO2 electrode successfully.Then the major work focused on the investigation of the different electrochemical performance of PbO2 anode before and after doping NiO and Ce.The high resolution scanning electron microscope(SEM),X-ray photoelectron spectroscopy analysis(XPS)and X-ray diffraction(XRD)were employed to characterize the morphology,crystal structure,elemental states of the modified anodes,respectively.Meanwhile,the cyclic voltammetry(CV),linear sweep voltammetry(LSV)and electrochemical impedance spectroscopy(EIS)were also performed to evaluate the electrochemical performance of the modified anodes.The results indicated that,compared with the block shape packed tightly of the Ti/TiO2NTs/PbO2(41.2 nm)and Ti/Ti02NTs/Ce-Pb02(34.6 nm)electrode,the Ti/Ti02NTs/Ni0/Ce-Pb02 electrode(15.2 nm)with more compact surface and a fine grain size possessed larger electrochemical active surface area,smaller charge transfer resistance and higher oxygen evolution potential.Phenol was chosen as the target organic wastewater and though the experiment of electro-catalytic degradation of phenol to study the influence of the initial phenol concentration,current density and pH value for obtaining the optimal degradation parameters with initial phenol concentration of 50 mg/L,current density of 40 mA/cm2 and the pH of 3.The removal efficiency of phenol and TOC reached 100.0%and 98.1%respectively after 180 min under the optimal conditions,demonstrating that the Ti/TiO2NTs/NiO/Ce-PbO2 electrode possess the batter electrochemical activity.The three-dimensional sphere-stacking PbO2 coatings based on one-dimensional Ti/TiO2NTs substrate(3D-sphere PbO2)were prepared without other three-dimensional templates,only by using a simple pulse electrodeposition method.The surface morphology,compositions and crystallographic structure of 3D-sphere PbO2 electrode were investigated fully by using the SEM,EDX and XRD,respectively.The comparative studies between 3D-sphere PbO2 electrode and traditional flat PbO2 electrode(flat-PbO2)indicated that the 3D-sphere PbO2 electrode with compact structure had smaller grain size.The electrochemical performances of the 3D-sphere PbO2 electrode were carried out by using CV,LSV,EIS and accelerated service life,respectively.The results show that the 3D-sphere PbO2 electrode has larger electrochemical active surface area,higher oxygen evolution potential and lower charge transfer resistance,leading to it possesses better stable service life on process of degradation than that of the flat-PbO2 electrode.The catalytic performances of the flat-PbO2 and 3D-sphere PbO2 electrodes were compared by degrading the 100mg/L phenol solution at the optimum current density(30 mA/cm2).And the results showed that the phenol removal efficiency could reach about 96.5%at the process of degradation,which was higher than that of the flat-PbO2 electrode(73.1%).In addition,degradation of phenol at two different electrodes condition were following the pseudo-first-order kinetics and the reaction rate constant(k)of 3D-sphere PbO2 electrode degrading phenol solution was 2.56 times larger than that of flat-PbO2 electrode.Summarily,the 3D-sphere PbO2 electrode with compact structure possessed not only strongly catalytic activity but improved the service life span.