An electrochemical sensor based on rhodamine B hydrazide-immobilized graphene oxide for highly sensitive and selective detection of Cu(ii)

Abstract

A novel strategy for fabricating a Cu²⁺ sensor based on rhodamine B hydrazide (RBH)-immobilized graphene oxide (GO) was reported. The thiol-modified Au electrode was functionalized by carboxyl functionalized GO through intermolecular interactions, followed by chemical bonding with RBH. The developed nanocomposite was used as an electrochemical sensor for detecting Cu²⁺ in aqueous solution using electrochemical impedance spectroscopy analysis with a detection limit of 0.061 nM within the range from 0.1 to 50 nM. Furthermore, the interference from potentially interfering ions such as Hg²⁺, Ag⁺, Cr²⁺, Fe²⁺, Pb²⁺, Ba²⁺, Mn²⁺, Co²⁺, and Ni²⁺ associated with Cu²⁺ analysis could be effectively inhibited. In addition, the developed Cu²⁺ sensor could be reproduced up to 10 cycles. In this approach, the fluorescent probe RBH can be replaced by other fluorescein derivatives which could identify the corresponding ions, which makes the approach a widely applicable strategy for metal ion detection.