Synthesis Of Vanadate/g-C₃N₄/Ag Photocatalyst And Its Photocatalytic Properties

Due to the violent conflict between growing energy demand and limited global fossil fuel storage,the development of sustainable energy resources has become one of the humanity's most pressing tasks.Among all types of sustainable energy,becauseof its abundant reserves,universality,high capacity and environmental friendliness,solar energy is considered to be a promising source of energy.However,solar radiation is essentially dispersed,fluctuating and intermittent.Therefore,the effective using of solar energy in a clean,economical and convenient way remains a huge challenge.Solar energy is mainly utilized by photothermal,photovoltaic and photocatalytic methods.Through artificial photosynthesis,dye photodegradation and photocatalytic chemical synthesis,solar photocatalysis can be converted into chemical energy,which can realize the application of solar energy in various fields.Owing to the photocatalytic reaction process,different photocatalysts are usually applied to achieve high efficiency.And semiconductor materials have been extensively studied for their excellent chemical,physical and electrical properties.In view of the increasingly serious environmental pollution problems in today's society,finding an efficient environmentally friendly catalyst has become a hot issue in the research field.With the increasing contradiction between human energy demand and energy shortage,the development and utilization of new energy,especially solar energy,has also become more important.Because of its mild reaction conditions and its ability to directly convert solar energy into chemical energy,photocatalysis has attracted the attention of researchers.The photocatalytic reaction can convert solar energy into chemical energy,such as photolysis of water to produce hydrogen,photoreduction of carbon dioxide,etc.,if it can be applied on a large scale,it can effectively alleviate the above contradiction.In addition,photocatalysis can also use solar energy to degrade organic pollutants,reduce heavy metal ions,and achieve self-cleaning.It is also an ideal environmental pollution control technology.Photocatalysis has shown great application prospects in the fields of energy and environmental protection.Duing to its unique energy band structure,simple preparation method,low cost,stable chemical properties and environmental protection,the graphite phase carbon nitride?g-C₃N₄?semiconductor photocatalyst has attracted attention in the field of photocatalysis.In particular,under the irradiation of visiblelight,g-C₃N₄ can effectively activate molecular oxygen,and generate superoxide radicals for photocatalytic conversion of organic functional groups and photocatalytic degradation of organic pollutants.This method is one of the ideal ways to deal with environmental pollution problems.However,since g-C₃N₄ is a polymer,the specific surface area is small,the band gap is large,and the quantum efficiency in the catalytic process is low,so it cannot be widely used.In this thesis,vanadate/g-C₃N₄/Ag composite photocatalytic materials were successfully prepared by one-step hydrothermal method and photodeposition method using graphite phase carbon nitride?g-C₃N₄?as the matrix.X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FTIR?,transmission electron microscopy?TEM?,ultraviolet-visible absorption spectroscopy?UV-vis?were used to characterize the experimental samples to demonstrate that nanocomposite photocatalysts were successfully synthesized.After complexing with rare earth vanadate and Ag nanoparticles,the photocatalytic activity of g-C₃N₄ is significantly improved,which is mainly due to the plasmon resonance effect?SPR?of silver nanoparticles and the effective separation of electrons and holes in the composite system.At the same time,the stability of the photocatalyst was verified by four cycles of degradation of methyl orange?MO?,and the possible mechanism of photocatalytic reaction was verified by the mechanism of degradation of methyl orange.