Efficient “turn-on” nanosensor by dual emission-quenching mechanism of functionalized Se doped ZnO nanorods for mercury (II) detection

Abstract

Mercury, a highly toxic contaminant is a detrimental environmental pollutant that causes severe health problems in human beings and developing an economical, rapid, and efficient technique for determination of Hg2+ ions at low concentrations remains a challenge. Herein, we report the preparation and application of orange-red luminescent Se doped ZnO nanorods (NRs), by a mechanothermal method, that was coated with 3-mercaptopropionic acid (3MPA), a chelating ligand to detect mercury ions because of strong affinity of –SH functionality. The formation of nanosensor with MPA was confirmed by the presence of an S2p3/2 peak at 162.7 eV, an absence of –SH stretching bond at 2566 cm−1 and reduction of crystalline nature from XPS, FTIR and XRD techniques, respectively. In the presence of Hg2+ ions, 3MPA–Se doped ZnO nanoprobe show efficient turn-on (restoration) photoluminescence over dual emission-quenching phenomenon owing to increased zeta potential (− 17.06 mV) and anti-aggregation effect induced by rapidly separated 3MPA surface ligands bound to selenium doped ZnO within 30 s. Additionally, a linear fit of photoluminescence (PL) spectrum for various concentrations of Hg2+ ions provide compelling evidence for emission (R2 = 0.990) over quenching (R2 = 0.888) mechanism which is in support of our proposed mechanism. Therefore, this “turn-on” MPA-coated Se doped ZnO nanosensor is employed for selective detection of Hg2+ ions with the lowest limit of concentration to 1 pM. These results demonstrate that our direct, rapid and effective approach for mercury detection using this nanoprobe will offer a great potential for monitoring Hg2+ ions from the environment and in healthcare applications. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.