Ultra-long ZnO/carbon nanofiber as free-standing electrochemical sensor for dopamine in the presence of uric acid

Abstract

Dopamine (DA) and uric acid (UA) have similar peak potentials in vivo, and it is difficult to distinguish them by general electrode material. Here, we used a magnetron sputtering method to sputter the ZnO seed layer on carbon fiber and prepare ultra-long ZnO nanofibers/carbon fibers (ZnO NF/CF) electrode by in situ hydrothermal method. As a free-standing electrode, not only electrochemical detection of DA and UA but also a separation of oxidation potential peaks of DA and UA can be achieved. In addition, in the case of high concentration UA (0.1 mM), ZnO NF/CF shows high sensitivity and selectivity and shows a wide linear range for DA (4–20 µM). Meanwhile, we proposed the electrochemical mechanism and process of DA and UA on the surface of ZnO, which helps us to understand the simultaneous detection of DA and UA by such electrochemical electrodes.