MoS₂ Modified Screen Printed Carbon Electrode Based Flexible Electrochemical Sensor for Detection of Copper Ions in Water
Deepan Kumar Neethipathi, Ajay Beniwal, Adrian M. Bass, E. M. Scott, Ravinder Dahiya
Abstract
Heavy metal ions (HMI), such as Cu <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}+}$ </tex-math></inline-formula> , are harmful to the environment and our health. Such ions are typically measured using glassy carbon electrode (GCE)-based electrochemical sensors developed on rigid substrates. However, several emerging applications require such sensors on flexible, and even disposable, substrates. Herein, we present a molybdenum disulfide (MoS2)-modified screen-printed carbon electrode (SPCE)-based flexible electrochemical sensor for the detection of copper ions in the water. The sensor exhibits excellent response with a limit of detection (LOD) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.43 \mu \text{M}$ </tex-math></inline-formula> for Cu ions in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5 \mu \text{M}$ </tex-math></inline-formula> - 5 mM. The developed sensor is compared with MoS2-modified conventional GCE using electrochemical impedance spectroscopy (EIS). The comparative studies show better linearity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{{2}}$ </tex-math></inline-formula> value <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim $ </tex-math></inline-formula> 0.99) for SPCE-based sensor and underline how easily they can detect Cu ions. The interference study, i.e., detection of copper ions in the presence of other HMI-based analytes, also shows the excellent response of SPCE-based flexible electrochemical sensor—thus, demonstrating their practical application is the detection of Cu in water.