Modification And Photoelectrocatalytic Properties Of CdSe Thin Film Electrode

TiO2 is the most commonly used catalyst for semiconductor research on the photoelectrocatalytic oxidation technology.However the catalytic activity is not high due to its wide band gap, the property that could only absorb shortwave of ultraviolet light,narrow response wavelength range for natural light. The CdSe photocatalyst,which needs the wide range of wavelength for incident light, could provide a new method to raise the utilization efficiency of sunlight.In this paper, the circulation volt-ampere galvanic deposit technology was firstly used to prepare the CdSe thin film electrode, which would be applied to visible light photoelectrocatalytic degradation of pesticide simulation of wastewater. Then the Co-CdSe thin film electrode was prepared by pulse current method and the photoelectrocatalytic degradation of aniline and phenolic organic wastewater using this thin film electrode was studied. The specific contents include:(1) The preparation and electrical properties of CdSe and Co-doped CdSe thin film electrodeCdSe film electrode was prepared by cyclic voltammetry electrodeposition technique,with ITO (indium tin oxide) conductive glass substrate, The optimum coating conditions was established through the open circuit voltage and short circuit current:pH 1.75, scan period is 17 weeks, scan rate of 0.07V/s, scan range of-0.2- -1.7V. And the thin film marerials prepared were characterized by scanning electron microscopy, transmission electron microscopy, energy spectrum analysis The results showed that the thin film was in a good degree of substrate attachment, CdSe particles were oval-shaped, diameter of 0-50nm, dimension was nearly uniform. Energy spectrum analysis showed that the proportion of selenium atoms and cadmium atoms was close to 1:1. Co-doped CdSe thin film electrode was prepared on the ITO (indium tin oxide) conductive glass by pulse-current deposition. The optimum conditions were:Co doping amount of 0.5x10-3 mol/L, pH 1.5, 1s:3s of deposition time and interval, cycle times of 600 times, the voltage of-1.3 V, The AC impedance spectra of Co-doped CdSe film electrode on the different substrates (ITO conductive glass, stainless steel plate, copper plate, nickel plate), was investigated. and Co-doped CdSe thin film electrode with nickel plate substrate having smallest impedance ring cycle radius and the best photoelectrochemical property was also found.(2) The photoeletrocatalytic properties of CdSe thin film electrodeA three-electrode photoelectrocatalytic reaction system consisted of CdSe thin film electrode prepared on the ITO conductive glass by cyclic voltammetry electrodeposition technique as working electrode, platinum electrode as counter electrode, saturated calomel electrode as reference electrode was used for the photoelectrocatalytic degradation of isocarbophos, imidacloprid and beta-cypermethrin respectively. Experimental initial conditions for the initial concentration of 20mg/L of the Isocarbophos and imidacloprid,40 mg/L of the beta-cypermethrin 100mL, supporting electrolyte NaCl 0.1mol/L,0.6V anodic bias applied, using 150W tungsten-halogen lamp irradiation 3h, The degradation rates were 73.6%,39.7% and 61.8% respectively.(3) The photoeletrocatalytic properties of Co-doped CdSe thin film electrodeA three-electrode photoelectrocatalytic reaction system consisted of Co-doped CdSe thin film electrode prepared on the ITO conductive glass as working electrode, platinum electrode as counter electrode, saturated calomel electrode as reference electrode was used for the photoelectrocatalytic degradation of simulated wastewater of dinitroaniline and p-nitrophenol. The experimental conditions were:the initial concentration of 20mg/L of the dinitroaniline and p-nitrophenol of 100mL, supporting electrolyte Na2SO4 0.1mol/L, applied anode bias 0.6V, using 150W tungsten-halogen lamp irradiation. The result showed that:after 6h degradation, the degradation rate for dinitroaniline was 25.5%, p-nitrophenol was 25.9%.Co-doped CdSe thin film electrode on the different substrates (ITO conductive glass, stainless steel plate, copper plate, nickel plate) was used for the photoelectrocatalytic degradation of the two kinds of organic wastewater above. The result showed that the deposition of nickel-board Co-CdSe thin film degradation was of the highest rate after 6h degradation:the degradation rate of dinitroaniline was 52.8%, p-nitrophenol was up to 81.1%. It is explained that Co-doped CdSe thin film electrode with nickel plate substrate has great visible light catalytic property for the photoelectrocatalytic degradation of aniline and phenolic organic compounds.