Preparation, Characterization And Application Of Silver Sulfide With Different Morphologies By Microwave-Assisted Method

As a representative of binary metal sulfides, silver sulfide is a direct, narrow-band gap semiconductor with good chemical stability, excellent photoelectric and thermoelectric properties, who has a band gap of Eg≈1 eV at room temperature. Silver sulfides in different morphologies, have unique physical and chemical properties and wide potential applications. Traditional synthetic methods of silver sulfide always have some defects, for example, operation complicated, long reaction time, easy to produce some impurities especially in template method.Microwave-assisted method is a novel materials synthesis method. The efficiency of heating can be improved by the energy import mode of microwave. Compared with the traditional method, it has many advantages, such as a short reaction time, lower reaction temperature, narrow distribution of particle size, good dispersibility, less reunion and good crystallinity. The microwave non-thermal effect can also affect the formation of crystal shape. However, there are only few researches report that silver sulfides were prepared by microwave-assisted hydrothermal method using household microwave oven, in which some microwave reaction conditions can’t be controlled exactly. In this paper, some silver sulfides with different morphologies were prepared in a microwave oven. Silver sulfides were finished on cotton fabric to study their antibacterial and antiultraviolet properties.Silver sulfides with different morphologies (hollow carambola-shaped, rod-shaped and nanowire-shaped) were prepared with silver nitrate, thiourea, sodium chloride and diethanolamine as raw materials by microwave-assisted method, at low temperature of below 100℃ and open system, in which the complexes of Ag+ and thiourea were prepared by crystal growing up slowly during standing or by reacting fast with high concentration.In this paper, reaction conditions, such as concentration of raw materials, standing temperature, standing time, the amount of diethanolamine, microwave temperature and time were studied. The result shows that morphologies and sizes of complexes of Ag+ and thiourea are depended on standing temperature, standing time and concentration of raw materials. The hollow structures and the hydrolysis and aging of complexes are depended on the amount of diethanolamine, microwave temperature and time. The formation mechanisms of silver sulfides with different morphologies have also been discussed in the paper.Silver sulfides with different morphologies were finished on cotton fabric to study their antibacterial and antiultraviolet properties. The result of antibacterial property shows that all finished cotton fabrics have great non-eluting antibacterial properties and antibacterial rate reach more than 90%. The antibacterial results for gram-positive bacteria are better than gram-negative bacteria. However, the eluting antibacterial properties of fabrics are poor, which can’t meet the standard requirements. The result of antiultraviolet property shows that all finished cotton fabrics have great antiultraviolet effect and their values of UPF reach 50+.In conclusion, silver sulfides with different morphologies were prepared successfully by microwave-assisted method according to the mechanisms of the hydrolysis and aging of complexes, then finished on cotton fabric to study their antibacterial and antiultraviolet properties and the results were satisfied. The method in this paper is simple, fast, energy-efficient, safe and green, while effectively overcomes the defects with impurity in template method. The formation mechanisms of silver sulfides with different morphologies also have been discussed deeply in the paper, which can provide a reference for more preparation of new materials.