Application of carbon nanotubes and graphene to develop the heavy metal electrochemical sensor

Abstract

Carbon nanotubes (CNTs) and graphene are carbon-based materials with great potential for electrochemical sensing in various applications such as for the environmental, biological, and physical sensors. For environmental applications, the sensor used to detect heavy metals such as cadmium (Cd), lead (Pb), mercury (Hg), iron (Fe), and other heavy metals that present in the water qualitatively and at the lowest limit of detection value. The uniqueness of their structures and chemical properties has attracted many researchers to develop carbon-based electrochemical sensors for environmental applications. These carbon materials are low-dimensional, thus providing the elevated aspect ratios and subsequently able to increase the sensitivity of the sensor probe. In the meantime, the graphene has its advantages in terms of its large surface area per unit volume to absorb and trap the molecules on the surface. In theory, the carbon atom is in the mid-range of electronegativity and can thus form a stable covalent bond with other molecules. These two materials are therefore consistent to bond with other functional groups such as amine, aldehyde, carboxyl, and thiol groups. All these functional groups can be functionalized with specific ligands or receptors for that particular heavy metal to provide specific and sensitive detection. Convenience in terms of their functionality, making them the center of attention as versatile platforms for functionalizing and designing an electrochemical sensor probe based on applications of concern. This paper focuses on reviewing carbon-based electrochemical sensors development to detect heavy metal in water for real-time monitoring of water quality, thus providing a brief overview of the sensor design reported previously.