Ligand reduction and cation exchange on nanostructures for an elegant design of copper ions photoelectrochemical sensing

Abstract

Copper is a fundamental element of good health, but exposure to the abnormal concentration will result in various neurodegenerative diseases. Photoelectrochemical (PEC) technique has attracted strong research interests as a potential tool for the development of copper ion sensors. However, the limited dynamic linear ranges restrict their use in practical settings and the working mechanism needs to be further clarified. Herein, an elegant design for copper ions PEC sensing was proposed using 3-thiopropionicacid-capped CdTe quantum dots (QDs) as both photoelectric beacon and recognition element. This working mechanism was based on in situ formation of CdTe-Cu2Te heterostructures as a result of 3-thiopropionicacid ligand reducing Cu2+ to Cu+ and Cu+-Cd2+ ion-exchange on nanostructures. This unique principle was confirmed by fluorescence quenching spectrum and XPS characterization. The convenient PEC sensor exhibits a wider linear range (1 nmol L−1–10 μmol L−1), and a lower detection limit of 0.4 nmol L-1 than other reported detection methods. Additionally, it has additional advantages of cost-effectiveness, simplicity, and selectivity. It provides a promising approach for the monitoring of copper ions in aqueous systems.