Facile synthesis of silver sulfide quantum dots by one pot reverse microemulsion under ambient temperature

Abstract Silver sulfide quantum dots have shown large potential in applications such as photocatalysts, solar cells and sensors due to their excellent photovoltaic performances, chemical stability and low toxicity. In this work, size-controlled silver sulfide quantum dots were successfully prepared by a water/AOT/isooctane reverse microemulsion system, in which hydrophilic silver ions were successfully dispersed in oil phase (isooctane) serving as silver source and the sodium sulfide solution were wrapped in aqueous droplets serving as the “nano reactor”. The results indicate that monoclinic silver sulfide quantum dots with the controlled size from 3 to 8 nm can be synthesized by fine tuning the content of silver ion and reaction time, while the products show broad absorption spectrum from NIR to UV–vis region and intensive NIR fluorescence around 1140 nm wavelength. Further, a possible crystal formation mechanism of silver sulfide quantum dots was proposed.