Preparation And Visible Light Photocatalytic Properties Of Carbon Nitride Based Composite Photocatalysts

As a new type of semiconductor material,carbon nitride has been became the focus of research in the field of materials since 1980 s.The graphitic carbon nitride（g-C₃N₄,denoted as CN）is a kind of non-metal semiconductor materials with two-dimensional lamellar structure,which has good anti-acid and alkali properties,themal and chemical stability.Therefore,CN has a potential application prospect in the field of photocatalysis.However,the photocatalytic efficiency of individual CN is restricted by the fast recombination of the photogenerated electron-hole pairs and low quantum efficiency,leading to the low photocatalytic activity.Therefore,researchers construct CN-based nanocomposite to promote the separation of electron hole and the utilization of sunlight,and improving the photocatalytic activity.This paper constructs several CN-based ternary heterojunction nanocomposite,the prepared samples were characterized by a series of characterization.Meanwhile,the visible light photocatalytic activity and stability of the composites were studied.The possible mechanism of visible light photocatalysis was further discussed.As follows:1.The ternary nanocomposite of g-C₃N₄/RGO/ZnS（CN/RGO/ZS）was prepared through a facile precipitation route.The prepared samples were characterized by a series of characterization.The as-obtained CN/RGO/ZS composite exhibit distinctly enhanced photocatalytic activities toward the degradation of RhB（10 mg/L）under visible light irradiation,which was about 1.04,1.17 and 5.38 times higher than those of CN/RGO,CN/ZS and RGO/ZS.The enhanced photocatalytic performance of RGO/CN/ZS sample arisesfrom the synergistic effects of three components: effective chargeseparation,multistep transfer between CN/ZS heterojunction and RGO nanosheets,and enhanced visible-light absorption.2.The graphene-bridged RGO/CN/BVO（RGO/CN/BVO）Z-scheme ternary nanocomposite photocatalyst was fabricated by a facile hydrothermal method.The prepared samples were characterized by a series of characterization.The as-obtained RGO/CN/BVO photocatalyst exhibit distinctly enhanced photocatalytic activitiestoward the degradation of TC（35 mg/L）under visible light irradiation,which was about 1.13,1.16 and 1.41 times higher than that of RGO/CN,CN/BVO and RGO/BVO.Meanwhile,the cycling experiments and the XRD patterns after cycling experiments reveal that the RGO/CN/BVO photocatalyst has excellent stable degradation ability in the photocatalytic process.The enhanced photocatalytic performance should be ascribed to the RGO excellent electron mobility and Z type nanoheterojunction system,which could lead to more desirable visible-light absorption capability and higher separation efficiency of photo-generated electron-hole pairs,therefore enhancing the photocatalytic degradation of TC.3.Novel visible-light-driven Z-scheme system CNT/g-C₃N₄/Bi2WO6（CNT/CN/BWO）ternary photocatalyst was obtained using hydrothermal method.The crystal structure,morphology and optical characteristics of the samples were characterized by XRD,TEM and XPS.The as-obtained CNT/CN/BWO photocatalyst exhibit distinctly enhanced photocatalytic activities toward the degradation of tetracycline（TC,35 mg/L）,which was about 1.1,2.5 and 1.5 times higher than that of CNT/BWO,CNT/CN and CN/BWO.The enhanced photocatalytic performance should be ascribe to the CNT excellent electron mobility and Z type nanoheterojunction system,which could lead to more desirable visible-light absorption capability and higher separation efficiency of photo-generated electron-hole pairs,therefore enhancing the photocatalytic activity.The cycling experiments reveal that the CNT/CN/BWO photocatalyst has excellent stable degradation ability in the photocatalytic process.