Preparation Of SrTiO₃-based Nanocompsite Materials Andtheir Photocatalytic Properties For Hydrogen Productio

SrTiO₃ has the advantages of semiconductivity,non-toxic,stable chemical properties,low cost and good photoelectric properties.Because of these advantages,SrTiO₃ has been widely used in the field of photocatalytic decomposition of water.The band gap of SrTiO₃ is 3.2 eV,which can only absorb the ultraviolet light.However,with respect to the solar spectrum,only a small fraction?ca.4%?of the incoming solar energy lies in the ultraviolet region,which greatly limits its use of solar energy.In order to utilize solar energy more efficiently,great efforts have been made to expand its absorbance edge in visible light range,in order to improve its photocatalytic hydrogen-production performance.In this paper,SrTi O₃ nanoparticles were successfully synthesized by hydrothermal method.Moreover,the prepared SrTiO₃ nanoparticles were modified by loading metal particles and coupling semiconductors.By using these methods,Au/SrTiO₃ and g-C₃N₄/SrTiO₃ nano-composite photocatalysts were prepared in order to improve the photocatalytic activity of SrTi O₃ nanoparticles.The major research points are summarized as follows:First,titanium dioxide nanoparticles were used as titanium source prepared by hydrothermal method and Sr?OH?₂·8H₂O was used as strontium source.The mixture of TiO₂ and Sr?OH?₂·8H₂O was put into the Teflon-lined hydrothermal vessel to prepare SrTiO₃ nanoparticles.Moreover,the SrTiO₃ nanoparticles prepared under different temperature were characterized and their photocatalytic performances were tested.The results show that the diameter of SrTiO₃ nanoparticles is about 30 nm,and they can only absorb the ultraviolet light.Among them,the sample synthesized under 180?has the optimal crystalline and photocatalytic activity.Therefore,the SrTiO₃ nanoparticles synthesized under 180?were chose as subject in the study.In order to make the prepared SrTiO₃ nanoparticles absorb the visible light,Au nanoparticles were loaded on the SrTiO₃ nanoparticles by photochemical reduction method to obtain Au/SrTi O₃ composite photocatalyst.The structure,composition,morphology,size and optical property of the as-prepared photocatalysts were characterized by using X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,scanning electron microscope?SEM?,transmission electron microscope?TEM?,EDS-mapping and UV-Visible diffuse reflectance spectroscopy?UV-Vis DRS?.The photocatalytichydrogen-productionperformanceofAu/SrTi O₃plasmonic photocatalysts was test under visible light.The results show that SrTiO₃ nanoparticles were successfully prepared by hydrothermal method.Due to the surface plasmon resonance?SPR?effect of Au,the SrTi O₃ nanoparticles exhibited the improved light absorption in the visible-light region.Moreover,the effect of different Au loading amounts on the photocatalytic hydrogen-production activity of SrTiO₃ plasmonic nano-photocatalysts was investigated.Among them,the 5%Au/SrTiO₃ photocatalyst showed the highest hydrogen production activity.In addition,the photocatalytic mechanism was also discussed.In addition,g-C₃N₄ semiconductor photocatalyst was prepared by pyrolysis condensation of melamine.The prepared g-C₃N₄ and SrTi O₃ nanoparticles were mixed and heat treated in the muffle furnace to obtain the g-C₃N₄/SrTiO₃ composite semiconductor photocatalyst for improving the photocatalytic properties of SrTiO₃nanoparticles.The prepared samples were characterized by XRD,SEM,TEM and DRS techniques,and their performances of photocatalytic hydrogen production from water splitting were tested under visible light.The research results show that g-C₃N₄/Sr Ti O₃composite semiconductor photocatalysts were successfully prepared by hydrothermal method.The obtained photocatalysts can split water into hydrogen under visible light and photocatalytic performance of SrTiO₃ was improved.It is attributed that the coupling of g-C₃N₄ and SrTiO₃ expands the light absorption range of Sr TiO₃nanoparticles.Moreover,the electrons and holes cane be separated effectively,resulting the enhancement of photocatalytic hydrogen-production performance of SrTiO₃ under visible light.