| Nowadays, energy crisis and environmental pollution have become global problem thathuman beings are facing. The construction of a clean, environment friendly, renewable newenergy system of non-fossil fuels has developed the focus of world attention and importantstrategy. It is generally accepted that solar energy will play an important role in thedevelopment of new energy sources since it is abundant, clean and renewable. Semiconductorphotocatalyst can produce hydrogen by photo-splitting water as well as degrade organicpollutants in wastewater, which is a kind of “green” and environmental protection technology.In this paper, the promising ZnIn2S4was selected as a photocatalyst and both its modificationand catalytic performance were studied, which aimed at enhancing its catalytic activities. Themain contents are as follow:(1) A series of ZnIn2S4photocatalysts doped with different amounts of nitrogen(N-ZnIn2S4) were prepared by using ZnIn2S4and urea, where ZnIn2S4was obtained viahydrothermal route as precursor and urea was employed as nitrogen source. These as-preparedsamples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM),UV-Visible absorption spectra(UV-Vis) and X-ray photoelectron spectroscopy(XPS). Theeffect of N dopant amount in the N-ZnIn2S4on crystalline structure and photocatalyticperformance of methylene blue(MB) degradation under visible light illumination wasinvestigated. The results indicate that N doping can influence the crystalline structure andmorphology of ZnIn2S4and enhance visible light absorption of photocatalysts. Theperformance of MB degradation was remarkably improved by using N-ZnIn2S4comparedwith pure ZnIn2S4, and N-ZnIn2S4exhibited quite good catalytic stability. Meanwhile, themechanism for enhanced photodegradation activity was also analyzed.(2) The core-shell TiO2@ZnIn2S4composite photocatalysts were prepared byhydrothermal method without templates, organic solvents or surfactants. The crystal structure,morphology and optical properties of the samples were characterized by using XRD, TEMand UV-Vis techniques. XRD results showed that TiO2@ZnIn2S4sample was successfullyobtained by hydrothermal synthesis method, and TiO2adding would not change ZnIn2S4polymorphs; TEM images proved TiO2@ZnIn2S4composite photocatalyst sample had a novel core-shell structure; UV-Vis spectra could further illustrate the TiO2adding slightly reducedvisible light absorption of ZnIn2S4. TiO2@ZnIn2S4composite photocatalyst displayed anenhanced catalytic performance under visible light irradiation for4h, and MB degradationrate reached91%. This is because the uniform and close contact between ZnIn2S4and TiO2can form a special core-shell structure which helps to achieve synergy effect and promote theseparation of photogenerated electron-hole pairs, thereby improving the photocatalyticactivity of the sample system.(3) A series of ZnIn2S4photocatalysts incorporated with different amounts of CuO(CuO/ZnIn2S4) were prepared by the impregnation-calcination method, where ZnIn2S4wasobtained via hydrothermal route as precursor and Cu(NO3)2was employed as impregnationsolution. These as-prepared samples were characterized by X-ray diffraction(XRD), scanningelectron microscopy(SEM), UV-Visible absorption spectra(UV-Vis) and nitrogen sorptionanalysis. The effect of CuO loading amount on structure of CuO/ZnIn2S4and photocatalyticperformance of methylene blue(MB) degradation under visible light irradiation wasinvestigated. XRD results proved that CuO/ZnIn2S4samples were successfully prepared. TheSEM images, BET measurement and UV-Vis results indicate that CuO addition can influencethe morphology, specific surface area and enhance visible light absorption of ZnIn2S4,respectively. The performance of MB degradation was remarkably improved by usingCuO/ZnIn2S4compared with pure ZnIn2S4, and the degradation of MB rate up to97%withoptimum ca.10mol%CuO loading. Moreover, the mechanism related to the enhancedphotodegradation activity was also analyzed. |
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