Highly fluorescent silicon quantum dots decorated silica microspheres for selective detection and removal of Au3+ and subsequent catalytic application

Sensitive detection and efficient removal of Au 3+ are important for environmental monitoring and remediation. In this study, silicon quantum dots (SiQDs) were prepared with 3-aminopropyl trimethoxysilane as the silicon source and boric acid as the doping substance to enhance fluorescence quantum yield. The obtained SiQDs possessed fluorescence sensing ability of Au 3+ and were successfully decorated on the mesoporous silica microspheres (SiO 2 ), giving SiO 2 -SiQDs. Owing to the high affinity for Au 3+ and the relatively large surface area, the SiO 2 -SiQDs exhibited not only selective fluorescence detection of Au 3+ in water matrix with a relatively low limit of detection (13.67   μg   L −1 ), but also efficient adsorption of Au 3+ with a maximal adsorption capacity of 530.7   mg   g −1 . Besides, the Au 3+ adsorbed on the SiO 2 -SiQDs could be in-situ reduced into evenly dispersed small-size gold nanoparticles, showing high catalytic efficiency for the reduction of 4-nitrophenol. The remarkable performance of SiO 2 -SiQDs on detection, adsorption and reusability demonstrated its multi-purposed applicabilities.