Preparation Of TiO₂/Nanocarbon Macroscopic Composite Material And Study On Its Photocatalytic Performance

At present,the pollution caused by the widespread use of toxic organic dyes is the main concern of the environmental protection industry.Excessive release of dyes into water sources will affect human life and the entire biosphere.Photocatalysis is one of the most effective methods to treat toxic organic dyes in water.TiO₂ is one of the most studied semiconductor photocatalytic materials.It has the characteristics of high UV sensitivity,good chemical stability,non-toxicity,and low cost.It also has significant photoelectric properties and has been the most widely used in the field of photocatalysis.the study.However,TiO₂ has a low photocatalytic efficiency due to the faster recombination rate of photogenerated electron-hole pairs.Nano-carbon materials such as carbon nanotubes,graphene,graphene oxide and reduced graphene oxide,etc.,are compounded with semiconductor catalysts due to their good adsorption,high crystallinity,wide band gap,high surface area and fast electron transmission speed.Later,the lifetime of photo-generated electron-hole pairs can be prolonged and the photocatalytic performance of a single semiconductor material can be improved.However,most of the composite semiconductor photocatalyst materials studied at this stage are discrete powders,which are not easy to recover and recycle.Therefore,the preparation of a composite semiconductor photocatalyst with a macrostructure is of practical significance.Based on this research background,this paper selects two nano-carbon materials,carbon nanotubes（CNTs）and graphene oxide（GO）,and prepares TiO₂/nano-carbon composites and TiO₂/nano-carbon macro-composites by hydrothermal method,and researches And analyzed the crystal structure,microscopic morphology,surface defects,photocatalytic performance and recycling performance of the prepared material.The specific research content is as follows:（1）The TiO₂/CNTs nanocomposite photocatalytic material was prepared by hydrothermal method.By changing the diameter of carbon nanotubes,the effect of the diameter of carbon nanotubes on the properties of the composite was explored.The results show that the composite material TiO₂/CNTs-100 prepared from carbon nanotubes with a diameter of 100 nm has the best photocatalytic performance,with a degradation efficiency of 96.6 % within 60 min,followed by carbon nanotubes with a diameter of 50 nm.The degradation efficiency of TiO₂/CNTs-50 prepared by tube and TiO₂/CNTs-25 prepared by carbon nanotubes with a diameter of 25 nm is the lowest.However,the photocatalytic efficiency of TiO₂/CNTs composite photocatalytic materials is higher than that of single TiO₂,and more than half of the methyl orange solution has been degraded in the first 30 minutes,indicating that the prepared TiO₂/CNTs nanocomposite has rapid photodegradation ability.（2）The TiO₂/RGO nanocomposite photocatalytic material was prepared by a one-step hydrothermal method,and the orthogonal experiment method was used to explore the influence of the reaction temperature,reaction time and reaction solvent ratio on the photocatalytic performance of the composite material.The optimal experimental conditions are as follows: the reaction temperature is 180 °C,the reaction time is 20 h,and the solvent ratio is water:ethanol=1:1.The photocatalytic performance of the sample prepared under this experimental condition was good,and the solution concentration was degraded by 94.5 % within 30 minutes.（3）According to the obtained optimal reaction conditions,prepare TiO₂/graphene foam（TiO₂/GF）composite photocatalysts and BiOCl/graphene foam（BiOCl/GF）composite photocatalysts with macrostructures,and compare their microstructures,surface morphology,and photocatalysts.Research on catalytic performance and photocatalytic cycle performance.The results showed that TiO₂/GF can degrade the solution concentration by 85.2 % within 80 minutes;BiOCl/GF can degrade the solution concentration by 90.4 % within 60 minutes.The used TiO₂/GF and BiOCl/GF were recycled for the second photocatalytic experiment,and it was found that the material still had photocatalytic performance,but the efficiency was reduced.