Rationally designed hydrophilic ZIF-rGO hybrids for bifunctional detection of trace Pb2+ and Cd2+ in river water

Abstract

Trace amounts of toxic heavy metal ions can contaminate water and soil and damage human health. Therefore, developing effective detection devices to monitor the content of toxic heavy metal ions in environmental contaminants is of great significance. In this study, a partially carbonized zeolitic imidazolate framework (ZIF)-decorated reduced graphene oxide (rGO) hybrid (ZIF/L-rGO) was synthesized and utilized as a bifunctional sensitive material for the electrochemical detection of trace Pb²⁺ and Cd²⁺. By rationally regulating the oxygen-containing functional groups on the rGO surface and doping ZIF nanoparticles, ZIF/L-rGO exhibited balanced hydrophilicity and good conductivity, thereby achieving superior charge transfer kinetics. For electrochemical detection of Pb²⁺ and Cd²⁺, ZIF/L-rGO-decorated electrode exhibited low limits of detection (Pb²⁺ 7.39 nM, Cd²⁺ 21.73 nM) and high sensitivity (Pb²⁺ 8.12 μA μM⁻¹ and Cd²⁺ 2.67 μA μM⁻¹), in a wide linear concentration range of 0.1–3 μM. The sensors based on ZIF/L-rGO-decorated electrodes were successfully used to detect trace levels of Pb²⁺ and Cd²⁺ in real river water with good anti-interference, reproducibility and stability. This study provides valuable insights into rational surface design strategies for graphene derivatives and their application in sensitive heavy metal ion monitoring.