Promoting effect of WS2 quantum dots on cathodic lucigenin ECL and its sensing application in Pb2+ detection

The present work focuses on developing a highly sensitive ECL sensor for Pb 2+ detection based on WS 2 quantum dots (QDs). A top-down sonication-assisted liquid-phase exfoliation method was employed to synthesize WS 2 QDs which were characterized by TEM, XPS, Raman spectroscopy and electrochemistry. It was found that WS 2 QDs could not only generate mild cathodic ECL itself but also significantly promote the cathodic ECL of lucigenin. The electrochemical results suggested that WS 2 QDs could effectively accelerate the reduction process of dissolved oxygen and lucigenin, thereby greatly amplifying the ECL intensity. The specific interaction between Pb 2+ and WS 2 QDs could significantly decrease ECL signal due to the depletion of WS 2 QDs, based on which an ECL sensor for detecting Pb 2+ was developed. Under the optimal condition, a good linear relationship between the inhibited ECL signal and the logarithm of Pb 2+ concentration was obtained in the range from 1 nM to 50 μM, with a low detection limit of 10.4 pM. Moreover, the fabricated sensor exhibited high sensitivity and excellent selectivity, and could be used for the sensitive detection of Pb 2+ in real samples.