Retention of lead sensitized terbium dopant emission in zinc sulfide nanoparticles in presence of co-existent metal ions: Detection of lead ion in aqueous media with nanomolar concentration by a facile post-synthetic reaction under pre-cation exchang

Suitable co-dopant(s) can electronically interact to tune the emission of inorganic nanoparticles (NPs). Such a case can be realized where post-synthetically added co-dopant Pb 2+ act as a co-sensitizer (in addition to the NP’s sensitization effect) for Tb 3+ emission in the terbium cation doped zinc sulfide [Zn(Tb)S] NPs in the pre-cation exchange reaction regimes under ambient conditions. This work evaluates possible practical utilization of this co-sensitization by this facile synthetic strategy for Pb 2+ detection in aqueous media in presence of co-existent M n+ [Na + , K + , Mg 2+ , Ca 2+ , Cd 2+ , and Hg 2+ ]. The Pb 2+ induced Tb 3+ emission enhancement is retained irrespective of these M n+ introduction in the media, with key mechanistic steps unperturbed. These outcomes ideally place using the Zn(Tb)S NPs to detect Pb 2+ in aqueous media. A limit of detection (LOD) and limit of quantification (LOQ) for Pb 2+ is estimated to be 3 ppb (15 nM) and 10 ppb (50 nM) from the pre-cation exchange conditions. The use of discussed strategy is verified using quantitatively contaminated drinking water and tap water by a spike recovery experiment. This provides a remarkable superiority by at least 2 orders of magnitude to detect Pb 2+ , over an alternate strategy using the cation exchange reaction conditions resulting from formation of lower band gap Pb(Tb)S NPs. The strategy presented unequivocally establishes that the rich light induced processes in the pre-cation exchange reaction conditions in the quantum dots can remarkably improve the Pb 2+ detection by virtue of accessing lower concentrations. • Pb 2+ co-sensitized Tb 3+ emission is retained in ZnS nanoparticles in presence of co-existent cations in aqueous media. • Key mechanistic feature of co-dopant spatial proximity remains unperturbed in presence of co-existent cations. • A facile post-synthetic modification in the pre-cation exchange reaction conditions detects Pb 2+ with a LOD of 3 ppb. • The pre-cation exchange reaction improves Pb 2+ detection by ~100 times, compared to that of cation exchanged counterparts.