The Preparation And Photoelectric Properties Of Fe₂O₃-based Binary Composite Nanomaterials

Hematite??-Fe₂O₃?is considered to be one of the most promising semiconductor photocatalytic material of degradating organic pollution due to its excellent chemical stability,low cost,environmental friendliness and narrow band gap width?1.9-2.2 eV?,up to 40%solar absorption efficiency.However,the iron oxide monomer material has poor absorption coefficient,low electrical conductivity,short excited life??10-12 s?,short hole diffusion length?2-4 nm?,and electron-hole pair fast composite speed affects the wide range of photocatalytic applications of hematite.Composite photocatalytic materials can make full use of the synergistic effect between heterostructures,effectively adjust the bandgap structure of semiconductor materials,and the heterointerface can effectively assist the photoinduced charge carrier migration and hinder the recombination of these charge carriers to enhance the efficiency of photocatalytic degradation of organic pollutants.Therefore,the design of composite photocatalysts based on heterostructures has become the focus of research on iron oxide-based photocatalytic materials.?1??-Fe₂O₃ nanoparticles with a size of 39±7 nm were prepared using ferric chloride and sodium acetate as raw materials.Then,a simple one-step method was used to prepare gold nanoparticles with a size of 3.8±0.8 nm using chloroauric acid as a raw material,hexane as a solvent,oleylamine as a template,and triisopropylsilane as a reducing agent.Finally,4-mercaptobenzoic acid was used as a bridging agent to obtain?different mass ratio?AuNPs/?-Fe₂O₃-x photocatalyst.Compared with the typical?-Fe₂O₃,the AuNPs/?-Fe₂O₃-0.1composite has a narrower band gap?1.88 eV?and a stronger photocurrent response?0.52 mA/cm²,which is 4.3 times of pure?-Fe₂O₃ photocurrent intensity?.The AuNPs/?-Fe₂O₃-0.1 composite has better photocatalytic degradation rate(0.222 h^-1)for the anionic dye methyl orange under visible light irradiation.?2?An easy method was used to prepare?different mass ratio?AuNWs/?-Fe₂O₃-x photocatalyst by using 4-mercaptobenzoic acid as a bridging agent.The photocurrent test results show that AuNWs/?-Fe₂O₃-0.1 has significant photoelectric properties:a larger photocurrent intensity of 0.46mA/cm²,which is 3.7 times of?-Fe₂O₃?0.12 mA/cm²?,and a better anionic dye?MO and CR?degradation efficiency.?3?SiO₂@?-Fe₂O₃-x core-shell structure was obtained by hydrolyzing ethyl silicate in iron oxide solution.The photocurrent test results show that the photocurrent density increases first and then decreases with the increase of the thickness of the silica coating.The photocurrent density of SiO₂@?-Fe₂O₃-0.5reaches a maximum of 0.27 mA/cm²,which is 1.6 times of?-Fe₂O₃.And the sample SiO₂@?-Fe₂O₃-0.5 showed the best photocatalytic degradation of RhB efficiency of 74.9%,compared with the pure?-Fe₂O₃ degradation rate increased by 10%.