Silver sulphide (Ag2S) quantum dots synthesized from aqueous route with enhanced antimicrobial and dye degradation capabilities

Mostly silver sulphide quantum dots have been prepared in the organic phase. An aqueous solvent-mediated process has been proposed for the synthesis of the silver sulphide (Ag2S) quantum dots (QDs). These Ag2S QDs were synthesized by using different amount of 3-MPA as a stabilizer. The structure and morphology of the prepared samples were determined by different spectroscopic techniques. XRD results proved that the prepared silver sulphide quantum dots have monoclinic structure. HRTEM results revealed the size of quantum dots were in the range of 8 nm to 9 nm.The minimum achieved size of the prepared silver sulphide quantum dot is 8 nm. The antibacterial activity of silver sulphide quantum dots are tested against Staphylococcus aureus, Klebsiella pneumonia and Escherichia coli by well diffusion method. The antifungal activity of samples was tested against Alternaria alternata and Rosellinia. Synthesized QDs have shown excellent antibacterial activity as the zone of inhibitions were in range of 21.25-7 mm. QDs were also screened for minimum inhibitory concentration (MICs) and minimum bactericidal concentration(MBC) which were 25.24-8.34 & mu;g/mL and 139.9-97.4 & mu;g/mL respectively. In addition to antimicrobial activities QDs were also tested for photocatalytic degradation of methylene blue dye. Scavenging experiments were also conducted to understand contribution of each radical for photocatalysis. More than 94% of the methylene blue dye has been degraded by using only5 mg of the QDs per 100 mL of the dye in 120 min. Scavenging activity of silver sulphide QDs for DPPH, Hydroxyl radical and superoxide radical was 63.1%, 58.1% and 56% respectively at 100 ppm.