Morphology-controlled electrochemical sensing of environmental Cd²⁺ and Pb²⁺ ions on expanded graphite supported CeO₂...

Heavy metal ions (e.g., Cd²⁺ and Pb²⁺) are widely existed in environment and highly toxic. Their convenient, sensitive, and selective determination is thus desirable. In this study, a novel electrochemical sensing interface is developed using the composite of CeO₂ nanomaterials supported on expanded graphite as the sensitive materials. As-prepared CeO₂ nanomaterials through a hydrothermal method feature different morphologies (e.g., nanocube, nanopolyhedra, and nanorod-shape). Electrocatalytic ability of this interface and sensing performance towards the monitoring of Cd²⁺ and Pb²⁺ ions rely on the morphology and structure of used CeO₂ nanomaterial. The interface using nanorod-shape CeO₂ nanomaterials supported on expanded graphite exhibits superior electrochemical activity, namely remarkable signal enhancement for the monitoring of Cd²⁺ and Pb²⁺ ions. The developed electrochemical sensor with this r-CeO₂/EG composite as the sensitive material delivers the detection limits of 0.39 and 0.21 μg L^-1 for Cd²⁺ and Pb²⁺ ions, respectively.