Controllable Preparation,modified And Visible-light Driven Catalytic Performance Of Pg-C₃N₄

Photocatalytic technology has been proved to be one of the most promising methods to solve both the world energy crisis and environmental pollution.Carbon nitride?g-C₃N₄?with low cost,narrow band gap and good chemical stability,is widely used in the field of photocatalysis.Nevertheless,the low specific surface area and the rapid recombination rate of photoelectron-holes are major disadvantages for g-C₃N₄,which seriously restrict its applications.In response to the above problems,the stuties on the following research carried out in this paper.The porous carbon nitride?pg-C₃N₄?was obtained by a thermal polymerization method using melamine as a precursor and porous silica as a hard template.The composition,micro-structure,and photoelectrical performance of pg-C₃N₄ samples were investigated by N₂ adsorption-desorption isotherms?BET?,scanning electron microscopy?SEM?,X-ray diffraction?XRD?,fourier transform infrared spectroscopy?FTIR?,X-ray photoelectron spectroscopy?XPS?,UV-vis diffuse reflection spectroscopy?UV-vis DRS?,photoluminescence spectroscopy?PL?,electrochemical impedance spectra?EIS?and photocurrent analysis?PT?,respectively.The results show that pg-C₃N₄ exhibits a lamellar structure with porous.For the porous structure of g-C₃N₄ the surface area increases,but the chemical composition and crystalline do not change.When the mass of melamine and porous silica is 2?1 and the heating temperature is 580?,the surface area of pg-C₃N₄?216 m²/g?is approximatly 15 times that of the bulk g-C₃N₄?14 m²/g?.The photocatalytic reduction of 4-NP was chosen as a model reaction to examine the catalytic activities of g-C₃N₄ and pg-C₃N₄.The results show that the photocatalytic rate of pg-C₃N₄ is about 8times that of g-C₃N₄.It shows the porous structure could effectively improve the photocatalytic performance of g-C₃N₄.Ag/pg-C₃N₄ composite particles were synthesized via microwave-assisted synthetic method using silver nitrate as a silver source.The composition,micro-structure and photoelectrical performance of Ag/pg-C₃N₄ nanocomposite samples were investigated by BET,SEM,XRD,FTIR,XPS,UV-vis DRS,PL,EIS and PT,respectively.The results reveal that the prepared Ag/pg-C₃N₄ has porous structure,and the surface area of Ag/pg-C₃N₄ is 175 m²/g.Silver nanoparticles?Ag NPs?are dispersed on the surface or between the lamellar of the pg-C₃N₄.The photocatalytic reduction of 4-NP was chosen as a model reaction to examine the catalytic activities of Ag/pg-C₃N₄ composite particles.The results show that when the silver concentration is 2.1 wt.%with sodium borohydride as reducing agent,the photocatalytic ability of Ag/pg-C₃N₄ nanocomposite particles is the best.Ag@Ag₂O/pg-C₃N₄ nanocomposite samples were synthesized via vacuum impregnation-roasting method using silver nitrate as a silver source.Ag@Ag₂O/pg-C₃N₄@CNF nanocomposite particles were prepared with an in situ synthesis method using carbon nanofiber?CNF?as the source of carbon.The composition,micro-structure,and photoelectrical performance of prepared samples were investigated by BET,SEM,XRD,FTIR,XPS,UV-vis DRS,PL,EIS and PT,respectively.The results reveal that Ag@Ag₂O/pg-C₃N₄ and Ag@Ag₂O/pg-C₃N₄@CNF have porous structure,the surface areas of Ag@Ag₂O/pg-C₃N₄ and Ag@Ag₂O/pg-C₃N₄@CNF are 189 m²/g and 153m²/g,respectively.The silver content of low does not change the crystalline of pg-C₃N₄significantly,while the CNF causes a crystal lattice distortion as postulated.The photocatalytic reduction of 4-NP was chosen as a model reaction to examine the catalytic activities of the prepared samples.The results show that when the silver content is 0.025wt.%,the heating temperature is 580?,and the mass of Ag@Ag₂O/pg-C₃N₄ and carbon nanofiber is 5?1,the photocatalytic ability of Ag@Ag₂O/pg-C₃N₄@CNF nanocomposite particles is the best.