The Performance Of 0D/2D Bismuth-based Homojunction Photocatalysts Modified By Quantum Dots

At present,the aquatic environment is facing severe challenges.A large number of pollutants enter the rivers,lakes,and seas,resulting in complex and multi-property composite pollution.Pollutants will gradually damage aquatic ecosystems and even endanger human health.In order to solve these problems,it is urgent to develop environmentally friendly and renewable technologies for environmental pollution treatment.Photocatalytic technology can directly use sunlight to eliminate pollutants,and it is hygienic,safe,and free of secondary pollution,which has attracted the attention of scientists around the world.Among all known photocatalysts,titanium dioxide?Ti O₂?has been extensively studied.However,the utilization of light by Ti O₂is too low.Therefore,it is necessary to find a new catalyst that can efficiently use sunlight.As typical visible light responsive photocatalysts,bismuth based semiconductors have attracted widespread attention.Bi₂WO₆and Bi₂Mo O₆have excellent chemical stability,appropriate band gap,and high photoactivity.They have a unique layered structure composed of perovskite-type layers.The special structure facilitates the quick separation of photo–generated charges.However,the high recombination of photo–generated electron–hole pairs will limit theirs photocatalytic activity.In response to this problem,We designed a zero-dimensional?0D?/two-dimensional?2D?bismuth-based quantum dot/nanosheet homojunction structure.The contents and results of the study are as follows:?1?Bi₂WO₆quantum dots?QDs-BWO?,Bi₂WO₆nanosheets?N-BWO?,Bi₂Mo O₆quantum dots?QDs-BM?,and Bi₂Mo O₆nanosheets were prepared by a simple hydrothermal method.The Bi₂WO₆quantum dot-nanosheet?QDs/N-BWO?and Bi₂Mo O₆quantum dot-nanosheet?QDs/N-BM?composites were formed through the electrostatic self-assembly process.And use TEM,XPS,DRS,PL and other instruments to research and analyze the prepared materials.?2?The photocatalytic degradation of Rhodamine B?RhB?and 4-chlorophenol?4-CP?under visible light was used to study the photocatalytic performance of QDs/N-BWO materials.In the experiment,the rate of photocatalytic degradation of RhB by 5wt%QDs/N-BWO was about 6.4 and 2.1 times higher than those of QDs-BWO and N-BWO;the rate of photocatalytic degradation of 4-CP by 5wt%QDs/N-BWO was about 4.5 and 2.5times higher than those of QDs-BWO and N-BWO.This indicates that the 0D/2D homojunction structure can promote the separation of photo-generated electron-hole pairs.Electrochemical and other test analysis also confirmed this.In the degradation of RhB,superoxide radicals?·O₂^-?and holes?h⁺?act together,and·O₂^-plays a major role.?3?Photocatalytic degradation of hexavalent chromium?Cr????wastewater and Cr???-RBY mixed polluted wastewater under visible light was used to study the light of QDs/N-BM Catalytic performance.Among all composite materials,the rate of photocatalytic degradation of Cr???by 8wt%QDs/NBM was about 4 times higher than N-BM,.In Cr???-RBY mixed polluted wastewater,the optimal concentration of RBY is 1 ppm,which is 2.5 times higher than when no RBY is added.The XPS test results show that Cr???is completely reduced to Cr???.The results show once again that The 0D/2D homojunction structure can effectively promote the separation of photogenerated electron-hole pairs.