Synthesis And Photocatalytic Properties Study Of Several Novel Micronano Materials

With the rapid development of economy and technology,people's life is more and more convenient,but the environmental and energy problems are more and more serious.For long-term sustainable development,people urgently need to find a green technology that can remediate the environment and replace non-renewable energy.Photocatalysis is favored by researchers because it can convert the inexhaustible solar energy into chemical energy that can be easily used by human beings without secondary pollution.However,the core of using photocatalysis is to find or synthesize suitable photocatalysts.Since Japanese scholars Fujishima and Honda made photocatalysis highly concerned in 1972,photocatalysis has experienced about 50 years of development.During this period,many kinds of photocatalysts have been designed and synthesized by scientists all over the world,and their application scope has also been broadened.However,the existing photocatalysts are still difficult to deal with all the environmental and energy problems.With the rapid development of economy and science and technology,the types and structure of pollutants become more complex,and the energy depletion is becoming more and more serious,so the current demand for photocatalyst is much higher.Therefore,it is imperative to continue to develop new photocatalysts and provide more solutions to environmental and energy problems.The main research contents are as follows:(1)The icker-like?-Ni(OH)₂/Bi₂O₂CO₃ composite was successfully synthesized via a simple one-pot hydrothermal manner.The photocataytic activity of?-Ni(OH)₂/Bi₂O₂CO₃ under UV light was studied by the degradation of mehyl orange(MO).The results showed that the photocatalytic activity of?-Ni(OH)₂/Bi₂O₂CO₃ was appreciably better than that of pure Bi₂O₂CO₃ and pure?-Ni(OH)₂.Based on the structure characterization,dispersibility(in water),cyclic stability,electron-hole pair separation efficiency,active species interaction and energy band analysis of?-Ni(OH)₂/Bi₂O₂CO₃,the reason why?-Ni(OH)₂/Bi₂O₂CO₃ has superior photocatalytic activity was explored,and the photocatalytic mechanism of?-Ni(OH)₂/Bi₂O₂CO₃ was proposed.In addition,the formation process of icker-like?-Ni(OH)₂/Bi₂O₂CO₃was explored,and the possible formation mechanism of?-Ni(OH)₂/Bi₂O₂CO₃ was proposed.(2)Monoclinic Bi VO₄ nanoparticles with controllable oxygen vacancy were synthesized via a hydrothermal approach combined with post thermal treatment.Through the study of diffuse reflection,impedance,transient photocurrent response and electron spin resonance,it was found that the oxygen vacancy level within Bi VO₄ nanoparticles could be modulated by varying the annealing temperature between 300 and 400 ^oC in an Ar gas environment,and it was revealed that different oxygen vacancy levels could effectively change the bandgap and carrier separation efficiency of Bi VO₄,resulting in changes in photocatalytic efficiency.The Bi VO₄nanoparticles with the optimal oxygen vacancy level showed a photocatalytic efficiency of98%,which was 38%higher than that of pure Bi VO₄ and had excellent cyclic stability.(3)A dual-purpose photocatalyst 4 wt%Au-Fe₂O₃/Ti O₂ was synthesized,which is expected to solve the environmental and energy problems.The Ti O₂/Au/Fe₂O₃ heterojunction photocatalysts with different Au loading were prepared via a metal-organic framework(MOF)assisted one-pot route using tetrabutyl titanate and ferric nitrate as precursors.The photocatalytic ability was evaluated through the removal of phenolic compounds 2,4-dichlorophenol(2,4-DCP)and 4-bromophenol(4-BP)and the H₂ production(water-splitting)under the visible light.The results show that 4 wt%Au-Fe₂O₃/Ti O₂ is the best for photodegradation and hydrogen production.By examining the special impact of different scavengers,it paraded that the hydroxyl and superoxide radicals mainly participated in the photocatalytic process.By investigating the ultraviolet visible diffuse reflectance(DRS),fluorescence emission(PL)and electrochemical impedance spectroscopy(EIS)of the catalysts,it was revealed that 4 wt%Au-Fe₂O₃/Ti O₂ had the advantages of excellent visible light response,low carrier recombination rate and fast migration rate,which were beneficial to improve its photocatalytic performance.In addition,4 wt%Au-Fe₂O₃/Ti O₂had good cyclic stability.This work delivers a novel perception to develop stable noble-metal photocatalytic materials with surface plasmon resonance(SPR)effect for the removal of phenolic compounds and the H₂ production in the industrial areas at the same time.