Recent progress on nanomaterial-based electrochemical dissolved oxygen sensors

Dissolved oxygen (DO) usually refers to the amount of oxygen dissolved in water. In the environment, medicine, and fermentation industries, the DO level needs to be accurate and capable of online monitoring to guide the precise control of water quality, clinical treatment, and microbial metabolism. Compared with other analytical methods, the electrochemical strategy is superior in its fast response, low cost, high sensitivity, and portable device. However, an electrochemical DO sensor faces a trade-off between sensitivity and long-term stability, which strongly limits its practical applications. To solve this problem, various advanced nanomaterials have been proposed to promote detection performance owing to their excellent electrocatalysis, conductivity, and chemical stability. Therefore, in this review, we focus on the recent progress of advanced nanomaterial-based electrochemical DO sensors. Through the comparison of the working principles on the main analysis techniques toward DO, the advantages of the electrochemical method are discussed. Emphasis is placed on recently developed nanomaterials that exhibit special characteristics, including nanostructures and preparation routes, to benefit DO determination. Specifically, we also introduce some interesting research on the configuration design of the electrode and device, which is rarely introduced. Then, the different requirements of the electrochemical DO sensors in different application fields are included to provide brief guidance on the selection of appropriate nanomaterials. Finally, the main challenges are evaluated to propose future development prospects and detection strategies for nanomaterial-based electrochemical sensors.