Ultra-sensitive detection of dopamine using oxygen plasma-treated Ti3C2Tx-modified carbon electrodes: DFT and experimental investigations

Abstract

Dopamine (DA) plays a critical role in various neurological disorders, including Parkinson's disease and schizophrenia, making its accurate and ultra-sensitive detection crucial for early diagnosis and treatment. In this study, a novel electrochemical sensor for DA detection was developed using monolayer Ti₃C₂T_x Mxene material treated with oxygen plasma. The oxygen plasma treatment significantly enhanced the surface activity and electronic transport capabilities of Ti₃C₂T_x, resulting in an ultra-low detection limit of 0.005 nM for DA. Electrochemical tests demonstrated the sensor's excellent sensitivity, stability, and performance. To further elucidate the underlying mechanisms of enhanced electrochemical performance, density functional theory (DFT) calculations were employed to investigate the impact of oxygen plasma treatment on the electronic structure of Ti₃C₂T_x. The DFT results revealed that the oxygen plasma treatment notably increased the number of active sites by introducing more oxygen-terminated functional groups on the surface of Ti₃C₂T_x. These oxygenated functional groups acted as catalysts, lowering the activation energy required for DA electrochemical reactions. Additionally, the oxygen plasma treatment effectively reduced the lattice constant of Ti₃C₂T_x, improving its internal electronic transport properties and thus enhancing its conductivity. The theoretical studies are in strong agreement with the experimental results, providing a clear understanding of the interaction between DA molecules and the oxygen-functionalized Ti₃C₂T_x surface. This research highlights the potential of oxygen plasma-treated Ti₃C₂T_x as a high-performance electrochemical sensing material and offers new perspectives for the development of sensitive biosensors.