Preparation,Characterization And Photocatalytic Properties Of NU-1000 Participating Composite Photocatalyst

The current rapid development of industry has caused serious energy and environmental crises.Photocatalysis offers a potential strategy to address these issues,as it can directly convert solar energy into usable or storable energy sources.However,the above applications require photocatalysts to have the characteristics of wide absorption range,long-term stability,high charge separation efficiency and strong redox ability.Unfortunately,it is often difficult for a single group of spectroscopic catalysts to satisfy all these requirements at the same time.Therefore,the designs of Z-scheme heterojunction photocatalyst Bi OI@NU-1000 and p-n heterojunction photocatalyst Cu₂O/NU-1000 overcome the shortcomings of single component photocatalyst and meet the above requirements.The performance of Bi OI@NU-1000in photocatalytic cracking of aquatic hydrogen and the performance of Cu₂O/NU-1000 in reducing CO₂ to CO were studied.This paper is mainly divided into the following two chapters:?1?In order to construct a Z-scheme heterojunction photocatalyst for photocatalytic hydrogen production,we used surface site engineering strategy to encapsulate Bi OI in the cavity of NU-1000,and synthesized three kinds of high-quality,highly dispersed,Bi OI@NU-1000-X?X=1,2 and 3?heterojunction materials with different compositions,and these materials were characterized by X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,and High-resolution transmission electron microscopy?HRTEM?,etc,indicating the crystallinity of the matrix,structure and composition,etc.The study found that the addition of Bi OI increased the absorption of visible light by NU-1000,and the formation of Bi OI@NU-1000 composite structure can effectively inhibit the rapid recombination of photo-generated electrons and holes.Through electron spin resonance?ESR?signal tests of the active species of the composite material under dark and light,it can be inferred that TEOA wasphotocatalytic cracking of aquatic hydrogen was carried out at the conduction band position of Bi OI.Under visible light irradiation,compared with the single NU-1000photocatalytic activity,the Bi OI@NU-1000 composite photocatalyst showed better photocatalytic activity,and suitable amount of Bi OI?Bi OI@NU-1000-2?can reach the best hydrogen production performance is 610?mol g^-1 h^-1 and has good cycle stability.This study shows that encapsulating Bi OI in the pores of MOFs is an effective strategy to improve the activity of MOF-based photocatalysts.?2?A new type of Cu₂O/NU-1000 p-n heterojunction was synthesized by microwave assistant method.The cubic crystal Cu₂O nanoparticles were supported on the surface of NU-1000 nanorods to form a p-n interface.The crystal structure,morphology and optical properties of the prepared samples were characterized by X-ray diffraction?XRD?,scanning electron microscope?SEM?,ultraviolet-visible diffuse reflection spectrum?UV-vis?,and fluorescence spectrum?PL?.The obtained Cu₂O/NU-1000p-n heterojunction composite has better photocatalytic activity for reducing CO₂under visible light irradiation than pure NU-1000.Among them,the performance of Cu₂O/NU-1000 to achieve the best photocatalytic reduction of CO₂ into CO is 11.3?mol g^-1 h^-1.The enhanced photocatalytic activity of the Cu₂O/NU-1000 composite is mainly due to the formation of p-n heterojunction between NU-1000 and Cu₂O,which makes the photoinduced electron hole pairs transfer through their interface faster.Three cyclic experiments show that the composite material has good photostability and recyclability,which may mean that the material is a promising new and efficient photocatalyst.