Unraveling the Potential of MXenes in Electrochemical Sensing: Mechanistic Insight, Design Principles, and Analytical...

MXenes, a rapidly expanding class of 2D transition metal carbides, nitrides, and carbonitrides, have emerged as promising materials for electrochemical sensing due to their metallic conductivity, hydrophilic surfaces, and tunable surface terminations. These properties enable efficient electron transfer, strong interfacial interactions, and versatile functionalization. However, despite extensive research, a clear mechanistic understanding of how MXene properties govern sensing performance remains limited. This review presents a mechanistic perspective on MXene-based electrochemical sensors, emphasizing the relationships between composition, surface chemistry, structural organization, and analytical performance. Key material characteristics-including surface terminations, interlayer interactions, and synthesis strategies-are examined in terms of their roles in charge transfer, catalytic activity, and analyte adsorption. A unified framework is proposed in which MXenes function as conductive scaffolds, electrocatalytic interfaces, and adsorption-driven platforms. Recent advances in major application areas, including small molecules, environmental pollutants, biomolecules, and pharmaceuticals are discussed, highlighting common design strategies and synergistic effects in hybrid systems. Finally, current challenges related to stability, reproducibility, and standardization are discussed. This perspective provides design guidelines for the development of next-generation MXene-based electrochemical sensors and supports their translation into practical applications.