Patterned Titanium Carbide (Ti₃C₂T_x) MXene Electrode for Electrochemical Detection of Phosphates

The discovery of two-dimensional transition metal carbides and carbonitrides (<i>MXene</i>) has laid the foundation of layered materials for number of potential future applications. The material embodies countless desired properties such as hydrophilic surfaces, high electrical conductivity, large surface to volume ratio and efficient absorption of electromagnetic waves. The unique properties of these 2D layered <i>MXene</i> materials have been explored largely in energy storage devices and electromagnetic shielding applications for decades. More recently, the material has attracted enormous interest in the field of chemical and biomolecule sensing owing to its varied chemical structure and ease of functionalization for sensitive and selective detection of different analytes. Phosphorus in the form of phosphates is an essential nutrient for many biological, environmental and agricultural processes that often needs strict monitoring to avoid detrimental effects. However, the complex oxidation states of phosphate in various pH conditions and its interferences with many ions in natural waters and the human body have made it difficult to develop a reliable and accurate method of sensing. Hence, the development of low cost, highly sensitive sensor materials are imperative for the rapid detection of phosphates. In this study, we explored the large-scale exfoliation of the widely studied Ti₃C₂T_x<i> MXene</i> materials by adopting minimally intensive layer delamination (MILD) etching route. Controlled chemical exfoliation conditions lead to selective removal of Al layer from Ti₃AlC₂ to form few layer <i>MXene </i>that are confirmed from structural and morphological conditions such as XRD, SEM, and AFM. The exfoliated Ti₃C₂T_x was used as an active electrochemical sensing platform for detection of phosphate by exploiting the redox behavior of phosphate complexed with molybdenum. The sensing of phosphates in the presence of interfering ions indicated low detection limit and high sensitivity along with a large linear detection range with reliable performance. Such an application of 2D MXene could make it a potential candidate for future environmental monitoring and sensing.