Effect of heat treatment on sensing performance of ZIF-67@GO for the detection of copper ions

A ZIF-67@GO composite has been successfully synthesized and used as active materials to construct an electrochemical sensor for the detection of copper ions. It is found that the heat treatment has great impact on morphology, specific surface area, pore structure, and charge transfer resistance, which leads to the distinction of the sensing performance. After the calcination at 150 °C for 2 h the combination mode for ZIF-67 and GO changed and the obtained ZIF-67@GO-2 exhibits a significant performance enhancement. Under the optimal experimental condition, ZIF-67@GO-2 indicates a wide linear detection range of 0.06–20 µM along with a low detection limit of 0.069 μM (S/N = 3), which is far lower than that of the safety guidelines stipulated by the of US Environmental Protection Agency. A probable accumulation-reduction-stripping mechanism for copper ions detection was proposed and schematically exhibited. Consequently, the proposed method is applied to quantitatively detect Cu2+ in wastewater and satisfactory results have been achieved.