Electrochemical Sensors Based on Metal Oxide and Sulfide Nanostructures

Abstract

Electrochemical sensors are widely used in air and water quality testing, agricultural activities, medical diagnosis, food industries, defense, and forensic science. This is because of their fast response, portability, easy testing procedure, low cost, and considerable sensitivity. However, due to lack of selectivity and sensitivity, pristine electrodes used in electrochemical sensors are not suitable for accurate detection of analytes in real samples. But, the fast growing nanotechnology eliminates the existing practical issues and significantly facilitates the development of highly selective and sensitive electrochemical sensors for many kinds of analytes, including organic molecules and inorganic species in liquid and gas medium. Nanomaterials such as metals, metallic compounds, and carbon-based materials have been widely utilized as electrode materials in electrochemical sensor. In this chapter, we particularly focus on metal oxide and metal sulfide–based electrochemical sensors applied in techniques such as cyclic voltammetry, amperometry, differential pulse voltammetry (DPV), and square wave voltammetry (SWV). The development of metal oxides and metal sulfides–based electrochemical sensors are separately outlined. Initially, reasons for enhanced catalytic current response and better redox potentials of analytes at pure metal oxide/sulfide modified electrodes than pristine electrodes have been described. Then, the existing issues (low selectivity and instability) in pure metal oxide/sulfide modified electrodes have been addressed. Finally, improvement strategies including metal ion doping, surface functionalization, and composite formation in metal oxide/sulfide modified electrodes are described.