Synthesis And Photocatalytic Properties Of Titanium Dioxide Nanobelts And Its Composites

Energy and environmental are two major issues among the top 10 issues facing humanity in the future.It is the consensus of people to drive the world with the sunlight.Photocatalysis technology is a green technology with important application prospects in the energy and environment fields.TiO₂ is non-toxic,inexpensive and highly stable,and has been widely used in photocatalysis technology.However,the band gap of TiO₂ nanoparticles is large,resulting in a light response range only in the ultraviolet region,which hinders their effective use of sunlight.The paper improves the photocatalytic performance of TiO2 by changing the morphology of TiO2 and constructing heterostructure composites.The specific contents are:?1?In view of the difficulty in recycling TiO₂ nanoparticles,the paper firstly prepared titanate nanobelts by hydrothermal method.The TiO₂ nanobelts?TiO₂NBs?and the surface roughened TiO2 nanobelts?C-TiO2NBs?were obtained by heat treatment,acid etching and heat treatment,respectively.The synthesized samples were characterized by XRD,SEM,TEM,FTIR,UV-Vis,BET,etc.The photocatalytic activity of the sample was examined by photodegraded methylene blue?MB?with the synthetic sample as catalysts.The results show that TiO₂NBs are smooth one-dimensional nanobelt structures,and the surface of the nanobelts are exposed to the most active?001?crystal facet.Heterostructures are formed between the second phase TiO2 nanoparticles formed on the surface of C-TiO2NBs and the nanobelts.After 4 hours of UV irradiation,the photodegradation rates of MB by TiO2NBs and C-TiO2NBs were 87.5%and 99.4%,respectively.The experimental results show that the heterostructure enhances the photocatalytic performance of the nanobelts.?2?In order to adjust the light absorption range of TiO₂ materials and the photocatalytic performance under visible light,the silver oxide/roughened TiO₂nanobelts?Ag2O/C-TiO2NBs?were prepared by in-situ precipitation method.The morphology,structure and composition of the composites were characterized by various analytical instruments,and the photodegradation properties of the materials were studied.The results show that the synthesized Ag₂O/C-TiO₂NBs still maintain a good nanobelt structure,and Ag₂O nanoparticles are uniformly loaded on the surface of the nanobelts.The presence of Ag₂O increased the specific surface area of the composite,broadened the photoresponse range,suppressed the recombination of photogenerated carriers,and enhanced the photocatalytic performance under visible light.Ag2O/C-TiO2NBs can effectively degraded MB under both ultraviolet and visible light.After 4 hours of light irradiation,the photodegradation rates were 97.9%and 59.5%,respectively.The paper also proposed the mechanism of photocatalytic degradation of MB by Ag₂O/C-TiO₂NBs under visible light by detecting the active species in photodegradation process.?3?In order to further improve the photocatalytic performance of TiO₂ materials under visible light.In-situ precipitation method was used to load CdS nanoparticles on the surface of roughened TiO2 nanobelts,composite CdS/roughened TiO2nanobelts?CdS/C-TiO₂NBs?were obtained.The morphology,structure and composition of the composites were characterized by various analytical instruments,and the photodegradation properties of the materials were studied.The results show that the synthesized CdS/C-TiO₂NBs still maintain good nanobelts structure.The CdS nanoparticles are supported on the surface of the nanobelts with a diameter of approximately 6 nm.The composite composite increased the specific surface area,lowed the band gap,broadened the absorption region of light,suppressed the recombination of photogenerated carriers,resulted in enhanced photocatalytic activity.CdS/C-TiO₂NBs photocatalysts have good degradation effects in degraded MB under ultraviolet light and visible light.After 4 hours of light irradiation,the photodegradation rates were 96.1%and 99.7%,respectively.The photocatalytic degradation reaction is a first-order reaction,and the rate constant of the composite materials degraded MB under visible light is 44 times that of P25.The results of the reusability of photocatalysts indicated the photocorrosion of CdS under Vis-light can be suppressed by adding of EDTA-2Na,and the as-prepared catalysts showed novel reusability.Under visible light irradiation,the photocatalytic hydrogen production of CdS/C-TiO₂NBs showed that the hydrogen production rate of the composites was as high as 0.802 mmol/(g^-1h^-1),showing excellent photocatalytic hydrogen production activity.The paper also proposed the mechanism of photocatalytic degradation of MB by CdS/C-TiO₂NBs under visible light by detecting the active species in photodegradation process.