Nitrogen-doped modification of carbon fiber cathode with aniline for oxygen reduction catalysis in dissolved oxygen seawater battery

Abstract

Carbon fiber has been commercially applied as a cathode material in dissolved oxygen-seawater batteries (DO-SWB). However, the low concentration of dissolved oxygen in seawater and the limited activity of the oxygen reduction reaction (ORR) restrict the improvement of battery power density. In recent years, nitrogen doping of carbon materials has attracted significant research interest. In this work, aniline(An) was used as the nitrogen source, and nitrogen-doped electrodes were prepared via a one-step electrochemical treatment of polyacrylonitrile-based carbon fiber (PAN-CF) in a mixed solution of An and H₂SO₄ under optimized process conditions. The electrodes were characterized using scanning electron microscopy (SEM), Raman spectrum (Raman), and X-ray photoelectron spectroscopy (XPS), combined with electrochemical testing methods to evaluate the surface characteristics and ORR activity of the electrodes, followed by an analysis of the underlying mechanism. Electrochemical modification introduced defects on the carbon fiber surface and generated pyridinic functional groups, effectively regulating the electronic structure of the carbon material, increasing the number of active sites on the electrode surface, and enhancing oxygen adsorption and charge transfer capabilities. As a result, the nitrogen-doped electrode exhibited excellent ORR performance. The optimal electrode achieved an ORR onset potential of −0.12 VvsSCE and an ORRspecific current density of 510 mA/gat −0.4 VvsSCE, indicating promising application prospects as a cathode material for DO-SWB.