Regulation And Performance Optimization Of Photogenerated Electron Holes In Photocatalysis

Recent years,photocatalytic technology has broad application prospects in the environment and energy fields due to its going green and environmental protection.However,to achieve true industrialization of photocatalytic technology,there are still huge challenges.Among them,the low photocatalytic efficiency caused by the recombination of photo-generated carriers has become a bottleneck problem restricting the development of this technology.Therefore,how to optimize the photocatalytic efficiency through the regulation of photo-generated electron and holes becomes a hot topic in current catalytic scientific research.In this paper,the photo-generated charge separation effect is optimized by adjusting the defect structure of the catalyst,controlling the size and morphology,and adjusting the catalyst interface by different deposition methods,to optimize the catalytic performance.We also use multiple photocatalytic reactions to evaluate the performance optimization.The main results are as follows:1.The influence of defect structures on the photo-deposited metal nanoparticles have been systematically studied in our study.We demonstrate that the isolated oxygen vacancy(Ov)could serve as electron trapper and facilitate the formation of small photo-deposited metal nanoparticles while the Ov clusters act as electron-hole recombination sites in the PD process and only results in large metal nanoparticles.We further found that both the intensities and the structures of defects can be controlled by pre-treating TiO2 at high temperature,which provides us great opportunity to synthesize photo-deposited metal nanoparticles with optimized size distribution and catalytic performance.Our findings would greatly broaden and deepen the understanding of the influence of defects photo-generated charge separation and shed light on controllable synthesis of highly efficient active structures.2.A series of Au sol nanoparticle catalysts with different sizes(3-50nm)and different morphologies(spheres,cubes,rods and octahedrons)were prepared by the method of NaBH4 reduction of chloroauric acid and seed growth.And their size and morphology were characterized by transmission electron microscopy.In the experiment of photodegradation of methylene blue(MB)under 520 nm light,except that 3.5nm gold nanoparticles promoted the photodegradation of methylene blue,the amount of degradation increased to 53%,and all others had different levels of inhibition on photodegradation of methylene blue.Among them,the inhibition effect is octahedral>17nm spherical particles>cubes,which may be due to the different light absorption capabilities of nanoparticles with different shapes and sizes.Using a combination of precipitation and photo-deposition,and by adjusting the ratio of photo-deposited Au,we constructed a series of Au/TiO2 catalysts with the same loading but different Au sizes,and measured their diameters using transmission electron microscopy.In the photodegradation MO experiment under 520 nm light,Au/TiO2 catalyst with a size of 6.7 nm shows the best photodegradation activity.3.Using a combination of precipitation and photo-deposition,and by adjusting the ratio of photo-deposited Au,we constructed a series of Au/TiO2 catalysts with the same loading but different Au sizes,and measured their diameters using transmission electron microscopy.In the methane conversion experiment,as the size of gold increases,the methane conversion rate also increases.We will further study the effect of this different Au-Ti interface on photogenerated electron holes in the photocatalytic reaction through follow-up studies.