| In this thesis, a CuInSe2/(Zn, Ag, Cu)S composite photoelectrode was preparedwith the electrodeposition method on a glassy carbon electrode. The modifiedcomposite layer materials also included polythionine, polyaniline and a cyano-bridgedmixed coordination polymer containing rare earth ion. The composite photoelectrodehad an excellent photoelectrocatalytic performance under the visible-light irradiation.Using the60W incandescent light as visible light, the studies for photoelectrocatalyticdegradation behavior of two phenothiazine dyes such as methylene blue(MB) andtoluidine blue(TB) were carried out by the composite photoelectrode. Theexperimental results showed that two dyes could be degraded to colorlessmineralization in term of photoelectrocatalytic mode when adding a certain amount ofhydrogen peroxide into reaction cell and irradiating with visible light. Furthermore,the degradation rate of two phenothiazine dyes with the photoelectrocatalytic modewas significantly higher than that by using photocatalytic or electrocatalytic modealone under the same experimental conditions.This thesis consists of four chapters.The chapter one: The literature review of this thesis.In this section, we mainly introduced the four contents: firstly, the backgroundknowledge of this thesis; secondly, the remark about the semiconductor materials forthe photoelectrocatalytic purpose; thirdly, the depth oxidation technology for theorganic pollutants; finally, the academic innovation, the content and significance inmy thesis.The chapter two: Preparation, characterization and photoelectric properties ofCuInSe2/(Zn, Ag, Cu)S composite photoelectrode.A CuInSe2/(Zn, Ag, Cu)S composite photoelectrode was successfully prepared.In the fabrication process, CuInSe2photoelectric semiconductor material waselectrodeposited firstly on a glass carbon electrode and then some metal sulfides wereformed by using the successive ionic adsorption-reaction method. Scanning electronmicroscopy(SEM) and X-ray energy dispersive spectroscopy (EDS) were used to characterize the surface morphology and the elemental composition of thephotoelectric materials. The applicability of incandescent light as the experimentalvisible light source was confirmed in terms of measuring the emission spectrum andintensity characteristics of several familiar light sources. Moreover, the open-circuitvoltage, chronoamperometry and UV-vis absorption spectrophotometer techniqueswere used to investigate the photoelectric properties and the photoelectrocatalyticactivity of the composite photoelectrode, respectively. When the60W incandescentlamp was set on the1cm distance from the composite photoelectrode, thelight-induced open-circuit voltage and short circuit current of the compositephotoelectrode were measured as30mV and2.5μA, respectively. By means of thecomposite photoelectrode, the photoelectrocatalytic primary degradation rate formethylene blue (MB) had reached more than90%values when irradiating it only60minutes with a60W incandescent lamp.The chapter three: The photoelectrocatalytic degradation of methylene blue byCuInSe2/(Zn, Ag, Cu)S composite photoelectrode under visible light irradiation.Based on the results above, the CuInSe2/(Zn, Ag, Cu)S composite photoelectrodeas working electrode was further applied to the kinetic study of photoelectrocatalyticdegradation of methylene blue (MB) dye. After optimized the many effect factorsincluding of the bias potential, pH value, H2O2concentration, electrolyte and reactiontemperature, we had ascertained the best experimental condition: the bias voltage ofphotoelectrode was0.70V; the concentration of H2O2was0.23mmol·L-1; theconcentration of supporting electrolyte was0.1mol·L-1Na2SO4(pH=2.7); thedegradation temperature was50℃; the initial concentration of MB was0.05mmol·L-1and the its initial volume of40mL. Then, the photoelectrocatalytic degradation ratioof MB would reach more than80%values by using the CuInSe2/(Zn, Ag, Cu)Scomposite photoelectrode when irradiating it40min with the60W incandescent lamp.Through comparison testing, it was validated that the degradation rate of MB with thephotoelectrocatalytic mode was significantly higher than that by using photocatalyticor electrocatalytic mode alone under the same experimental conditions. On the otherhand, it was discovered the there existed an internal relation between the initial concentration of MB and the added amount of hydrogen peroxide concentration byanalyzing experimental data. That was showed as a good [MB]~ln ([H2O2]/[MB])linear relationship within the0.01~0.05mmol·L-1concentration range of MB. Thecomposite photoelectrode also exhibited the good stability, and thephotoelectrocatalytic activity for the degradation of MB was derogated afterundergoing200min continuous use.The chapter four: The photoelectrocatalytic degradation of toluidine blue byCuInSe2/(Zn, Ag, Cu)S composite photoelectrode under visible light irradiation.In order to study the photoelectrocatalytic properties of some homologuesbelonging to phenothiazines dyes. We also were focused on the kinetic study ofphotoelectrocatalytic degradation of toluidine blue (TB). The best experimentalcondition had ascertained: the bias voltage of photoelectrode was0.65V; theconcentration of H2O2was0.90mmol·L-1; the concentration of supporting electrolytewas0.15mol·L-1Na2SO4(pH=3.0); the degradation temperature was55℃; the initialconcentration of MB was0.04mmol·L-1and the its initial volume of40mL. Underthe best experimental condition above, the photoelectrocatalytic degradation ratio ofTB would reach more than85%values by using the CuInSe2/(Zn, Ag, Cu)Scomposite photoelectrode when irradiating it40min with the60W incandescent lamp,and the degradation rate of TB with the photoelectrocatalytic mode was doubled thanthat by using photocatalytic or electrocatalytic mode alone under the sameexperimental conditions. Moreover, as similar as the tendency for thephotoelectrocatalytic of MB, there also existed an internal relation between the initialconcentration of TB and the added amount of hydrogen peroxide concentration byanalyzing experimental data. That was showed as a good [TB]~ln ([H2O2]/[TB])linear relationship within the0.01~0.04mmol·L-1concentration range of TB. Inaddition, the composite photoelectrode had the good stability, and thephotoelectrocatalytic activity for the degradation of MB was derogated afterundergoing200min repetitive use. |
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