Construction Of Novel(Bis) Metal Oxide Heterojunction And Their Visible Light Photocatalytic Performance

Energy is an important criterion that determines the world economy.Due to the continuous development of industry,the increase in population and living standards has led to an energy crisis,and the consumption of fossil fuels has also increased.At present,the world is facing a double crisis of fossil fuel exhaustion and environmental pollution.All countries are looking for new energy sources that can be used for a long time without causing environmental pollution.Hydrogen peroxide（H₂O₂）is a valuable chemical substance used in paper,pulp,textile and electronics industries,wastewater treatment,chemical oxidation,etc.In various industries,the demand is growing rapidly.It is estimated that by 2024,the global H₂O₂consumption will reach 6000 tons.At present,many classic technologies for the production of H₂O₂have been developed,such as electrochemical synthesis,anthraquinone oxidation,and direct conversion of H₂and O₂synthesis.However,most of these methods may be subject to some restrictions,such as energy consumption,introduction of impurities,and explosion risk.Antibiotics,especially tetracycline（TC）,one of the stubborn antibiotics is widely used and it is neither completely absorbed by animals nor completely removed.Because of their complexes with metals and the continuous accumulation of their related complexes,they can cause teratogenesis and carcinogenesis.And increase the resistance of microorganisms,which increasingly threatens human health and ecological balance.Among the many strategies that have been developed,photocatalytic degradation has always shown its due prospects in eliminating various organic compounds used to purify water,and has also been widely used in hydrogen production,carbon dioxide reduction,and nitrogen fixation.Therefore,the development of efficient photocatalyst production for degradation of refractory pollutants and H₂O₂is an ideal strategy to solve environmental pollution and energy crisis.In this paper,the One-dimensional graded rod-like structure Bi OI@Cu Bi₂O₄Z-type heterojunction photocatalyst and the three-dimensional flower-like Bi@Sn₃O₄Schottky junction photocatalyst are designed and prepared for the production of H₂O₂and the degradation of pollutants.The main research contents of this paper are as follows:（1）3D graded rod BiOI@CuBi₂O₄semiconductor composite is successfully synthesized.Bi OI nanosheets are inserted into rod-shaped Cu Bi₂O₄to construct a Z-type heterostructure by solvothermal method,and this structure has larger specific surface area and richer active sites,which enhance the light absorption capacity of the material.Under visible light,the yield of H₂O₂reached 76μM in 150 min without any carbon emission or pollutants,which provided a green synthetic route and sustainable development technology for the production of H₂O₂.In addition,it is also used for the photocatalytic degradation of tetracycline（TC）,showing excellent photodegradation performance,and the improvement of its photocatalytic performance can be attributed to the formation of a Z-type heterostructure between the p-type semiconductor Bi OI and the n-type semiconductor Cu Bi₂O₄,which enables effective carrier transfer and reduces oxygen to generate active species for generating H₂O₂and degrading tetracycline.Finally,the capture agent is used to capture the active species to explore the mechanism of photocatalytic reaction,which provides a theoretical basis for the material photocatalysis to generate H₂O₂and degrade pollutants.（2）3D flower-shaped Bi@Sn₃O₄semiconductor photocatalyst is successfully prepared,and a simple electrostatic self-assembly process is used to embed Bi nanoparticles on the petals of Sn₃O₄self-assembled from 2D nanosheets to construct a three-dimensional flower-like Bi@Sn₃O₄Schottky junction,and it promotes the photocatalytic production of H₂O₂.The best sample Bi@Sn₃O₄-5 has the highest H₂O₂generation rate（112μM）under visible light irradiation（λ>420 nm）,which is about that of Sn₃O₄.Based on the results of free radical capture experiments,photoelectrochemical performance and energy band structure analysis,the possible generation mechanism of H₂O₂on Bi@Sn₃O₄photocatalyst is proposed,that is,"dual channel"method,including one step two-electron oxygen reduction and the mutual coupling of·OH.The enhanced photocatalytic performance is attributed to the formation of Schottky junctions,which accelerates the separation of charges and limits the recombination of charges.This work provides an in-depth understanding of the mechanism of photocatalytic H₂O₂production and provides ideas for the design of highly active materials for photocatalytic H₂O₂.