Preparation Of Polythiophene Modified Nano-molybdenum Disulfide And Its Photocatalytic Sterilization Properties

The problem of water-borne infectious diseases is becoming more and more serious,especially in developing countries,where millions of people die from water-borne diseases every year due to lack of sanitation.Pathogens are one of the main causes of water-borne diseases.Gram-negative bacteria Escherichia coli（E.coli）is a water-borne bacterial pathogen.These bacteria are also called an indicator organism and can be used to reflect the level of pathogens in water sources.Escherichia coli is considered to be the pathogen that causes acute diarrhea and bloody diarrhea,which can bring serious health problems,such as bloodstream infections,central nervous system diseases,peritonitis,colitis,bacteremia and urinary tract infections.Traditional sterilization methods such as the use of ultraviolet（UV）radiation,ozonation and chemical treatment with chlorine dioxide can be used to remove pathogens.However,most of these methods consume a lot of chemicals or energy,and may generate secondary pollution of the water environment.Recently,the use of semiconductor materials to generate reactive oxygen species（ROS）under visible light irradiation to destroy pathogens in aqueous solutions is considered to be an optimal method.Nano-molybdenum disulfide（MoS₂）has attracted attention due to its suitable band gap and good stability.MoS₂ has a unique structure with Mo and S unsaturated atoms at the edges,which can provide favorable edge activity during the photocatalytic process.However,due to the rapid recombination of photogenerated electrons and holes,the photocatalytic efficiency of pure MoS₂ is limited.In addition,MoS₂ nanosheets tend to agglomerate in water,and their surface is electronegative,which leads to insufficient affinity between bacteria and nanosheets and affects their antibacterial efficiency.Easy polymerized,good stability and low cost make conjugated polythiophene（PTh）one of the most potential conductive polymers.PTh has better light absorption capacity,which generates more photo-generated electrons and pores for photocatalytic reactions.In this paper,the structure and performance of MoS₂ were systematically studied,and then PTh was modified onto the MoS₂ nanosheets to greatly increase its absorption of visible light and reduce the probability of photo-generated electron-hole recombination.Furthermore,a water-soluble cationic conjugated polythiophene（PTh M）was designed and modified onto the MoS₂nanosheets.This method not only improves the photocatalytic activity of MoS₂ nanosheets,but also enhances its affinity with E.coli,which greatly improves the photo-bactericidal efficiency of MoS₂ nanosheets.The specific experiment content is as follows:（1）Three different methods,ultrasonic（US-MoS₂）,hydrothermal（HY-MoS₂）,and ion intercalation（IN-MoS₂）were used to prepare MoS₂.The structure and morphology of various MoS₂ were characterized by SEM,TEM,XRD,etc.Using Escherichia coli as a biological model,the antibacterial properties of three kinds of MoS₂ under visible light irradiation were studied.In order to determine the factors affecting the light-induced antibacterial properties of MoS₂,the morphology,structure and photocatalytic properties of MoS₂ prepared by different methods were systematically compared.The results showed that IN-MoS₂ has a higher metal phase content,better light responsiveness and smaller size compared with US-MoS₂ and HY-MoS₂.A possible antibacterial mechanism was proposed based on the capture agent experiment and ESR test.（2）The PTh/MoS₂ composite nano antibacterial agent was prepared by ultrasonic stirring method,and the morphology and structure of the nano antibacterial agent were studied by XRD,SEM and FTIR characterization methods.The antibacterial efficiency of PTh/MoS₂ can reach99%after irradiating for 90 min.The photobacterial properties of MoS₂ composite nano-antibacterial agents under different modification levels were further studied.The results showed that when the loading amount was 1 wt%,the antibacterial properties of PTh/MoS₂ composites were the best.At the same time,its photo-bactericidal mechanism was studied through the capture agent experiment and ESR test to study.The results showed that the probability of electron-hole recombination was reduced and more active oxygen was generated,thus improving the photo-bactericidal performance of MoS₂.（3）3-bromo-4-methylthiophene was used as raw material to gradually prepared PTh M through organic synthesis,then PTh M/MoS₂ composite nano antibacterial agent was prepared by ultrasonic stirring method,and the composite nano antibacterial agent was analyzed by XRD,SEM and FTIR characterization methods.The photocatalytic antibacterial performance of the composite material under light irradiation was studied.The results showed that the antibacterial efficiency of MoS₂ modified by PTh M can reach 99%after 60 min of light irradiation,indicating that the modification of PTh M greatly improves the photobacterial efficiency of MoS₂.The capture agent experiment and ESR test shows that the modification of PTh M reduces the probability of electron-hole recombination,thereby improving the photobacterial performance of MoS₂.