| The rapid development of modern industry causes the serious environment problem, the traditional ways of pollutant treatment have low efficiency and cost lots of time. Cuprous oxide, as a significant and typical p-type semiconductor with a direct band gap of 2.0-2.2 eV, have attracted much more attention due to its superior physical and chemical performance, which are widely applied in photocatalysis, photovoltaic devices, magnetic storage media, gas sensors etc. However, the high electron-hole pairs recombination rate of pure Cu2O limits its application in the photocatalytic field. Thus, some strategies, such as combination of Cu2O with another semiconductor, preparation of core-shell structure composite materials, loading some noble metals have been employed to solve these problems. In this paper, Cu2O crystals with different morphology, Cu2O core-shell structure composites, noble metal modified Cu2O crystals and two-phase semiconductor composite materials have been prepared to investigate the influence of morphologies and the exposed facets on the photocatalytic performance. The photocatalytic mechanism has been further discussed in details. The concrete research contents are as follows:Monodispersed and uniform cubic, cuboctahedron, octahedron Cu2O have been prepared by controlling the amount of PVP. The influences of the Cu2O crystals with different exposed facets on the adsorption performance were analyzed. The results show that these crystals with smooth surface have a good dispersion and uniformed morphology under the condition of 55?. The exposed (111) crystal plane has advantage to adsorb more pollutant molecules.A series of Cu2O-Cu7S4 compound semiconductors were prepared by controlling the concentration of sodium sulphide. Composites retained the morphology and structure of the Cu2O templates, and showed more excellent photocatalytic performance than pure Cu2O. With the sodium sulphide content increasing, the composites show an obviously core-shell structure. The etching effect can make crystal surface become rough and core-shell structure with interspace space appears. All of these are beneficial to adsorb more pollutant molecular and enhance the efficiency of photocatalytic reaction.Silver modified Cu2O crystals have been prepared by a one-step in-situ Ag-loading method. The silver nanoparticles directed growth on the surface of cubic Cu2O with the diameter about 10 nm. The structure and photocatalytic properties of as-prepared crystals were also investigated. Because of the existence of Ag nanoparticles, electron-hole pairs recombination rate can be reduced, photocatalytic performance of the samples was greatly increased.Cu2O-BiOBr composites were prepared by using cuboctahedron cuprous oxide as template, and the composite materials retained the morphology and structure of the Cu2O template. The photocatalytic degradation efficiency of these as-prepared samples are obviously improved, Cu2O-BiOBr-3 shows the highest efficiency (Cu2O-BiOBr-3>Cu2O-BiOBr-5>Cu2O-BiOBr-10). The BiOBr nano sheets attached on the surface of cuprous oxide can adsorb more pollutant molecules and speed up the photocatalytic reaction. Besides, BiOBr nano sheets adhered on the cuprous oxide crystals can form heterojunction with the Cu2O, which can improve the charge transfer rate between these two semiconductors and increase the separation rate of the electrons and holes. When the concentration of KBr and Bi (NO3)3·5H2O are higher, the surface of the Cu2O template are all covered with BiOBr nano sheets, which restrains the adsorption of pollutant molecules, then efficiency of photocatalytic degradation is decreased. |
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