Surface Oxygen Functionalization of Carbon Cloth toward Enhanced Electrochemical Dopamine Sensing

Metal elements, including noble and transition metals, have always been required in the design of electrochemical sensors. Despite great advances, some drawbacks like the release of metal ions and exfoliation of catalysts from substrates still exist. Acid oxidation treatment, as a simple and effective way, is commonly used in the surface treatment of carbon materials, extensively used either directly as capacitive and catalytic electrodes or as the current collectors. However, its potential to be directly applied for electrochemical sensing has not been explored enough. In this work, a metal-free electrochemical sensor based on a surface oxygen-functionalized carbon cloth (CC) is fabricated through a simple acid oxidation treatment, during which more oxygen-containing groups are introduced, ensuring the solvent-accessible hydrophilic surface of electrodes and the improved surface interaction with dopamine. Our results suggest that the enhanced dopamine sensing performance can be obtained just through the introduction of oxygen-containing groups. Compared with raw CC, the acid-oxidized CC (AOCC) exhibits improved electrochemical sensing performance. A high sensitivity (9320 μA mM–1 cm–2), a low detection limit (10 nM), and a wide linear range (0.1–104.5 μM) are achieved. The selectivity, stability, and reproducibility are also proved to be satisfactory. Furthermore, the flexibility of AOCC endows its promising potential in fabricating wearable and soft electronics for human healthcare monitoring.