Air plasma fast-induced defect-enriched carbon cloth for simultaneous electrochemical detection of dopamine and uric acid

Herein, we report a fast (10 min) and simple surface treatment of pure carbon cloth (CC) only by an air plasma. The structural characterizations indicate that the air plasma process brings out higher rugosity, more defects, and increased oxygen-related groups on CC surfaces than Ar- or N₂-plasma, which can offer abundant capture sites, large electroactive area, and superhydrophilic interface for analytes. As a result, the air-treated CC (CC-P_Air) electrode achieves a pronounced improvement of electrocatalytic activity for the [Fe(CN)₆]^3-/[Fe(CN)₆]^4- probe evidenced by increased peak currents, decreased peak-to-peak separation, and the lowered resistance of charge transfer. It is also demonstrated that the self-supported CC-P_Air electrode possesses excellent sensing performance toward dopamine (DA) and uric acid (UA). The feasibility of the simultaneous electrochemical detection of DA and UA can be verified by their large peak potential gap (∼112 mV) for differential pulse voltammetry. The chronoamperometric sensor yields wide linear ranges of 0.05-100 μM for DA and 0.5-300 μM for UA. The corresponding detection limits are estimated to be 2.6 and 20.4 nM for DA and UA, respectively. The sensor also displays satisfactory selectivity, stability, and reproducibility. Due to good flexibility, the CC-P_Air electrode presents great potential for manufacturing wearable and soft electronics for human health monitoring.