Study On The Preparation Of Go-Cu₂O Nanocomposites And Their Antibacterial Activity

In recent years, the researches about GO-Cu2O composites have been relativelyactive because of their excellent performance and they have been widely used in areaslike photocatalysis, solar cells, biosensors and so on. However, there are still manylimitations about the preparation of the composites, which restrict their manyapplications. Most of cuprous oxide particles deposited on graphene oxide that weresynthesized before were irregular and with large sizes. By contrast, a simplesolution-phase method is successfully introduced to synthesize Cu2O nanoparticleswith sizes of about25nm in this paper and antibacterial activities and photocatalyticproperties of nanocomposites loaded with this kind of Cu2O nanoparticles are bothdiscussed.The specific research progresses of this thesis are shown as follow:1. The preparation of Cu2O nanoparticles with different sizes and morphologiesDifferent cuprous oxide particles with sizes from about500nm to25nm aresynthesized through exploring different kinds of methods. And cubic Cu2O particleswith sizes of25nm are prepared by a simple solution-phase strategy at roomtemperature. Furthermore, Cu2O nanoparticles with different sizes and morphologiesare prepared through changing the sequence of ascorbic acid and sodium hydroxide aswell as the concentration of surfactant based on this solution-phase method.2. The preparation and characterization of GO-Cu2O nanocompositesWhat is different from preparing Cu2O nanoparticles, GO-Cu2O nanocompositesare syntherized by stirring graphene oxide and copper sulfate solution magneticallyfor half an hour before adding surfactants, sodium hydroxide and reducing regents.The GO-Cu2O nanocomposites prepared through a solution-phase method at roomtemperature are characterized by XRD、UV-vis and TEM. The corresponding resultsindicate that cuprous oxide nanoparticles can be distributed on graphene oxideuniformly and there are hardly any nanoparticles out of graphene oxide sheets. 3. The antibacterial activities of Cu2O nanoparticles and GO-Cu2O nanocompositesThe anti-microbial effects of Cu2O nanoparticles and GO-Cu2O nanocompositeson escherichia coli are studied. The results of inhibition zone and platecolony-counting tests indicate that the GO-Cu2O nanocomposites have longereffective antibacterial time compared with pure cuprous oxide nanoparticles and thereason is that graphene oxide can slow down the release of cupric ions. Andfurthermore, the antibacterial activity of Cu2O nanoparticles is stronger if their sizesare smaller. Except from that, the antibacterial ability of cubic Cu2O nanoparticles isstronger than that of irregular Cu2O nanoparticles. So this kind of nanocompositedeposited with cubic cuprous oxide particles with smaller sizes has relatively strongantibacterial ability except that it has long effective antibacterial time. So it is an idealantibacterial material and has a great potential in the applications of bacteriostasis.4. The photocatalytic activities of Cu2O nanoparticles and GO-Cu2OnanocompositesThe photocatalytic activity of Cu2O nanoparticles is studied. In theory, thesmaller the sizes of cuprous oxide nanoparticles are, the wider the gaps and thestronger the photocatalytic properties. But the results of corresponding experimentsillustrate that all the cuprous oxide nanoparticles prepared do not have photocatalyticactivity. In contrast, the photocatalytic activity of nanocomposites is also studied andthe results show that nanocomposites neither have photocatalytic activity except thatnanocomposites have strong absorption for methylene blue in the dark. The mainreason is that it is easy to have the behavior of visible-light driven photocorrosion ifthe size of cuprous oxide nanoparticles is small. Cu2O nanoparticles are oxidized fullyin the light to CuO which hardly have any absorption and photocatalytic activity formethylene blue.