Study On Preparation,characterization And Visible-light Photocatalytic Performances Of P-doped G-C₃N₄ And Ag₃PO₄/g-C₃N₄ Composites

Phosphate-doped polymeric g-C₃N₄ photocatalysts?P-doped g-C₃N₄?were prepared via a facile heating method with melamide and H3PO4 as precursor and doping agent,respectively.The synthesized samples were characterized by X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FTIR?,UV-vis diffuse reflection spectroscopy?DRS?,photoluminescence spectroscopy?PL?,elemental analysis?EIS?,X-ray photoelectron spectroscopy?XPS?,transmission electron microscopy?TEM?,scanning electron microscopy?SEM?,and specific surface area?BET?.The results reveal that the P-doping not only decreases the band gap of the doped g-C3N4,and improves the visible light absorption,but also greatly improves the separation efficiency of photegenerated electron-hole.pairs.The secondary calcination can further increase the visible light absorption and photogenerated electron-hole separation efficiency.In this dessertation,Rhodamine B was chosen as the model pollutant.The visible-light photocatalytic activity and stability of samples were investigated by evaluating the decomposition of Rhodamine B under visible light irradiation.The visible light photocatalytic activity of P-doped g-C₃N₄ materials is much higher than that of pure g-C₃N₄,and P-doped g-C₃N₄ with doping content of 2%exhibits the highest photocatalytic activity.The visible light photocatalytic stability of P-doped g-C3N4 is excellent.The second calcination is advantageous to the visible light photocatalytic activity of P-doped g-C3N4,and the visible light photocatalytic activity increases as the second calcination temperature increases,and the highest second calcination temperature is 620?.It is important to detect the main oxidative species in the photocatalytic process for clarifying the visible light photocatalytic mechanism.The capture agent experiments indicate that the hydroxyl radicals·OH might be the main active species in RhB photodegradation.Novel polymeric g-C₃N₄ photocatalysts modified by trace Ag₃PO₄ were prepared via a facile method.The photocatalytic activities of Ag3PO4/g-C3N4 samples were investigated by evaluating the decomposition of methyl orange under visible light irradiation.The results reveal that the modification of g-C3N4 using a small amount of Ag3PO4,can hardly affect the crystallinity of the as-prepared g-C3N4 materials,while can greatly improve their visible light absorption and separation efficiency of photogenerated electron/hole pairs.The Ag3PO4/g-C3N4 photocatalysts exhibit significantly enhanced photocatalytic performance for the degradation of methyl orange compared with pure g-C₃N₄.