Studies On TiO₂ Nanobelts Based Photocatalysts:Syntheses And Performance

In recent years,tremendous efforts have been devoted to exploring one-dimensional(1D)semiconductor nanostructures for extensive applications,such as solar energy conversion,photoelectrochemistry and photocatalysis.In particular,TiO2 nanobelts have garnered the most research attention due to their large specific surface area,enhanced light absorption and scattering,as well as fast and long-distance electron transport.However,the photocatalytic activity of TiO2 nanobelts is generally retarded by the limited active surface sites,fast recombination of photogenerated electron-hole pairs,and limited light absorption merely confined within the UV region.Therefore,research on the fabrication of TiO2 nanobelts-based heterostructure with a favorable band gap and a low lattice mismatch is studied towards the degradation of organic pollutants.Firstly,we have fabricated a well-defined TiO2 NB-CdS QD heterostructure by the electrostatic self-assembly buildup,and the photocatalytic performance of the as-assembled hybrid heterostructure was systematically probed.It was found that the TiO2 NB-CdS QD heterostructure exhibits significantly enhanced visible-light-driven photoactivity and favorable photostability as compared with blank TiO2 NBs,CdS QDs and randomly mixed counterparts.It can be attributed to the intimate interfacial contacts between CdS QD and TiO2 NB ingredients afforded by the electrostatic self-assembly buildup,which remarkably facilitates charge separation and lengthens the lifetime of photogenerated electron-hole pairs,thus giving rise to the significantly enhanced photocatalytic performances.Secondly,an efficient self-assembly strategy combined with a facile photoreduction approach has been developed for the construction of Ag/GR/SC-TNBs heterostructure.It was found that Ag/GR/SC-TNBs ternary nanocomposite exhibited significantly improved photocatalytic performances under UV light irradiation compared with those of blank SC-TNBs and binary counterparts owing to the formation of particles junctions and acicular pits junctions in which GR acting as efficient electron transporter and collector in conjunction with the Ag NPs as an"electron trap" simultaneously prolong the lifetime of the photogeneratedelectron-hole pairs,thus giving rise to the significantly enhanced photocatalytic performance.Thirdly,Ti02 nanobelts framework co-modified with GR and WO3 nanorod(i.e.TNBS/WO3/GR)have been fabricated via a simple electrostatic approach followed by a hydrothermal reduction process.It is revealed that the as-prepared TNBs/WO3/GRternary heterostructure exhibited significantly improved photocatalytic performances under UV light irradiation in comparison with blank TNBs and its binary counterparts due to the formation of GR wrapped WO3 nanorod/TiO2 nanobelt heterostructure in an intimate contact,in which GR acting as efficient electron transporter and collector in conjunction with WO3 serving as interfacial mediator simultaneously prolong the lifetime of photogenerated electron-hole pairs,thus giving rise to the significantly enhanced photocatalytic performances.In addition,the primary active species were determined by control experiments and underlying photocatalytic mechanism was elucidated.It is anticipated that our work will shed new insight for the construction of one dimensional TiO2 based heterostructure toward target photoredox reactions.