Photocatalytic Activity Of Single Atomic Pt And Co Modified G-C₃N₄ And R-TiO₂

With the high-speed industrial development,the global energy shortage and the environmental pollution have become increasingly serious.Photocatalytic technology is found as an effective method for pollutants degradation and hydrogen generation,which has attracted wide attention because of its environmental friendliness,low energy consumption and high efficiency for degrading organic pollutants.However,the utilization of photocatalytic technology is limited due to the shortcomings of photocatalytic materials such as low vis-light utilization,high recombination rate of photogenerated carriers,and poor catalyst stability.Therefore,the preparation of high efficiency photo-catalysts is an effective way to solve energy and environmental problems.At present,the modification of photocatalyst is mainly focusing on the doping of noble metals.However,due to low reserves and high price of noble metal,its wide application is limited.Therefore,the development of high-efficiency,stable and economical noble metal single-atom catalysts?SAC?has become an important issue in current research.In recent years,SAC have been widely used in the fields of light,electricity,and organic catalysis due to their special electronic and geometric structures.Based on this,the synthesis of high-efficiency and practical SAC and their application in photocatalytic degradation of pollutants and photolysis of water to hydrogen have become an urgent problem to be solved.The main research contents of this thesis are as follows:?1?Hydrogen production by Pt_x-CN photolysis and photocatalytic degrad-ation of phenol:using urea as precursor,carbon nitride?CN?was prepared by high temperature calcinations.Pt_0.1-CN,Pt_0.2-CN,Pt_0.3-CN,Pt₁-CN,Pt₂-CN and Pt₃-CN was fabricated by in-situ photoreduction method with chloroplatinic acid?H₂PtCl₆·6H₂O?as platinum source,and 300W xenon lamp with 420 nm filter as a visible light source.The Pt_0.1-CN was characterized by double spherical differential electron microscopy.The results demonstrate the successful preparation of single-atom Pt-loaded carbon nitride materials.Hydrogen production and photocatalytic degradation of phenol were carried out by using Perfect-light photocatalytic device.Through four hours hydrogen production reaction with Pt_0.1-CN under visible light illumination,the hydrogen production reached 473.82?mol·mg_pt^-1.Secondly,the photocatalytic degradation of phenol was also carried out.The degradation rate of Pt_0.1-CN was 100%after 150 min illumination.?2?Hydrogen production by Pt_x/R-TiO₂ photocatalytic dehydration and photocatalytic degradation of phenol:the defected titanium dioxide?R-TiO₂?was prepared as carrier using titanium trichloride as precursor,and the photode-position of Pt atoms was carried out with chloroplatinic acid?H₂PtCl₆·6 H₂O?as platinum source and 300 W xenon lamp as light source.The prepared single-atom Pt and Pt nanoparticles loaded R-TiO₂ were labeled as Pt_0.078/R-TiO₂,Pt_0.254/R-TiO₂,Pt_0.3/R-TiO₂,Pt_0.6/R-TiO₂,Pt_1.21/R-TiO₂.Subsequently,the Pt_0.254/R-TiO₂ photocatalyst was characterized by double spherical differential electron microscopy.It was found that Pt was uniformly dispersed on the surface of R-TiO₂ in a single atomic state.Hydrogen production and photocatalytic degradation of phenol were carried out using a Perfect-light photocatalytic device.The results showed that the hydrogen production of Pt_0.254/R-TiO₂photocatalytic material was 1714.55?mol·mg^-1_ptt for four hours.At the same time,in the degradation of phenol experiment,the degradation rate of Pt_0.254/R-TiO₂was 55.22%after 90 min illumination.?3?Photocatalytic degradation of BPA by Co_x/R-TiO₂:the single atomic Co1/R-TiO₂ catalysts were prepared with defected titanium dioxide?R-TiO₂?as carrier,and cobalt nitrate(Co?NO₃?_2·6H₂O)as cobalt source.The prepared four kinds of photocatalytic materials were labeled as Co_0.098/R-TiO₂,Co_0.245/R-TiO₂,Co_0.4/R-TiO₂,Co_0.6/R-TiO₂.Subsequently,it was characterized by double-spherical electron microscopy and XPS.The BPA was degraded by a photocatalytic degradation apparatus under a 300 W xenon lamp.The results showed that the degradation rate of Co_0.4/R-TiO₂ single-atom photocatalytic material reached 100%after 90 min illumination.The results show that the noble metal Co exists in the atomic state in the oxygen vacancies on the surface of R-TiO₂,thereby improving the stability of the photocatalyst and finally improving its photocatalytic activity.