Nearly monodisperse ZnS nanoparticles for portable recognition, enrichment and detection of Cd(II)

As cadmium ions (Cd 2+ ) pose a serious threat to environment and human health, it is significant to develop portable, fast-response and sensitive Cd 2+ sensors for both real-time and on-site collection of such critical information. In this study, nearly monodisperse ZnS nanoparticles (NPs) were prepared and used to recognize, enrich and detect Cd 2+ ions. ZnS NPs demonstrated fast adsorption kinetics towards Cd 2+ ions (removing 99.3 % of Cd 2+ in 12 min), surpassing previously reported multiple Cd 2+ adsorption materials. Upon adsorbing Cu 2+ and Cd 2+ ions via substitution reaction, ZnS NPs gain strong peroxidase activity, and demonstrate the ability to selectively detect Cu 2+ and Cd 2+ ions among common metal ions . By further conjugating with our previous HSnS NFs (Hollow SnS nanoflower) nanosensor to eliminate the interference of Cu 2+ , the ZnS NPs nanosensor could selectively detect Cd 2+ ions with recoveries above 80 %. The ZnS NPs nanosensor can cover a wide range of Cd 2+ concentration from 0.5 to 100 μg L −1 with an extremely low detection limit of 0.38 μg L −1 . When coupling to a portable RGB sensor, as low as 0.5 μg L −1 Cd 2+ ions could be reached on-site for river water, giving an outstanding recovery of 99.4 %. The current results provide a new avenue to the on-site detection of Cd 2+ ions, and would doubtlessly contribute to the future construction of portable and intelligent sensor arrays towards complex environmental samples.