Preparation And Photocatalytic Activity Of TiO₂/BiOCl Nanocomposite Photocatalysts

Titanium dioxide?TiO₂?nanoparticles ? BiOCl nanosheets and TiO₂/BiOCl composite catalyst were respectively prepared by sol-gel method,hydrolysis method and coprecipitation.The crystal structure,grain morphology,elemental composition and band gap characteristics of produced powder were determined by XRD?XPS?BET?SEM?TEM?EDS?EDX?UV-Vis and other means.The effects of calcination temperature?water contents and pH on TiO₂ catalyst of crystal structure,particle size,crystallinity and photocatalytic performance were systematically studied.For BiOCl catalyst,sodium dodecyl benzene sulfonate?SDBS?dispersant,HCl concentration,calcination temperature were systematically studied.And the TiO₂/BiOCl composite catalyst crystal structure,grain morphology,elemental composition were also analyzed.First systematic and comprehensive study of TiO₂ nanoparticles,BiOCl nanosheets,TiO₂/BiOCl composite catalyst on structure,morphology,adsorption properties and photocatalytic activity.On the basis of TiO₂ nanoparticles,BiOCl nanosheets performance,TiO₂/BiOCl composite catalyst were prepared with high adsorption and catalytic activity,and elaborated the link between the three catalysts.The shape of TiO₂ nanoparticles were round,and uniformly dispersed,TiO₂ particle size were about 12 nm and specific surface area were 99.94m2/g at 400?.The results showed that the crystallite size increases and the anatase phase transforms to the rutile phase at elevated temperature.According to the intersection of the tangent with the abscissa can be estimated by the band gap of the catalyst was 3.17 eV?anatase?and 2.94 eV?rutile?.The results showed that TiO₂-50-600 had the best photocatalytic properties.The dosage of TiO₂-50-600 was 1.0 g/L,illumination time was 1 h,pH=6.9,and the decolorization rate of methylene blue solution could reach 98.0%.BiOCl catalyst were composed of 2D BiOCl nanosheets,and uniformly distributed,the thickness BiOCl nanosheets in 5-10 nm,and it was petal structure.We studied the dispersant,the concentration of hydrochloric acid,and calcination temperature on BiOCl photocatalytic properties.After adding dispersant SDBS,it changed the nature of the interface between solid and liquid,BiOCl catalyst particles are uniformly dispersed,and having a different interface,and photocatalytic properties of the BiOCl catalyst can be improved.With the increase of the concentration of hydrochloric acid,adsorption properties of BiOCl catalyst first reduced and then increased trend.At C?HCl?= 1.0 mol/L,BiOCl catalyst had good adsorption and degradation.As the calcination temperature increasing,the rate of adsorption of methylene blue downward trend,the experimental results show that the adsorption properties of the BiOCl catalyst at 80?were best.TiO₂/BiOCl composite catalyst were composed of the 2D BiOCl nanosheets and TiO₂ particles,and uniformly distributed.TiO₂ nano-particles were attached on BiOCl nanosheets surface,TiO₂ particles and BiOCl nanosheets dispersed uniformly and petal structure.The thickness BiOCl nanosheets were in 5-10 nm,and TiO₂ particle size were about 7-10 nm.The degradation experimental of TiO₂/BiOCl composite catalyst were tested.Compared to pure TiO₂ photocatalytic,The degradation properties of TiO₂/BiOCl composites photocatalytic on methylene blue had effectively been improved,the degradation rate of the highest in the 150 min could closed to 100%,which was about 2 times of pure TiO₂.Analysis of the mechanism of photocatalytic activity of TiO₂/BiOCl composite catalyst,TiO₂ and BiOCl were forming a heterostructure,which could effectively improve the efficiency of degradation of methylene blue dye.This structure was advantageous electron-hole pairs separated,and inhibited their compound,it could be improved photocatalytic properties.