Vacuum plasma treatment on carbon nanoparticles for highly sensitive square wave voltammetric sensor of heavy metal ions

Abstract

Heavy metal ions are dangerous pollutants since they are non-biodegradable and accumulate in ecological systems. The identification of these ions is extremely important in environmental quality monitoring. However, despite the importance of detecting heavy metals, research on sensor electrode materials for sensing them is still insufficient. In the present study, we suggest functional group introduced carbon nanoparticles (CNPs) using a simple vacuum plasma process. Polypyrrole nanoparticles (PPyNPs) are used as carbon precursors to produce CNPs and various functional groups are introduced following exposure with different gases (NH3, C4F8, and O2) during the vacuum plasma process. Plasma-treated CNPs show fast charge transfer and high sensitivity to the heavy metal ions (Pb2+ and Cu2+). Particularly, O2 gas-treated CNPs (O-CNPs) possess an excellent sensing ability as compared to the other treated CNPs. Under optimized conditions, O-CNPs show a limit of detection (LOD) of 0.005 μM for Pb2+ and 0.01 μM for Cu2+. O-CNPs also show a linearity for the detection signal of metal ions over a wide concentration range (0.01–100 μM for Pb2+ and 0.1–100 μM for Cu2+).