Chemical activation of nitrogen-doped carbon derived from chitosan with ZnCl₂ to produce a high-performance gas diffusion-type oxygen electrode

In this study, we fabricated nitrogen-doped carbons (NDCs) derived from chitosan using a new synthesis method that combines the thermal decomposition of chitosan and chemical activation with ZnCl₂. Then, the effect of the activation temperature on the microstructure of NDCs was investigated. The performance of a gas diffusion-type oxygen electrode (GDE) using the obtained NDCs was evaluated using an oxygen reduction reaction in an alkaline solution. Finally, the relationship between the microstructure of NDCs and electrode performance was discussed. The surface area and total pore volume of the fabricated NDCs tended to increase with activation temperature, despite decreasing nitrogen content. Additionally, we found that the overpotential of GDE decreases with an increase in specific surface area and total pore volume. The microstructure of the NDCs was found to play a key role in improving the performance of GDEs. Furthermore, the GDE composed of fabricated NDCs with a high surface area and high pore volume exhibited a reduced activation overpotential than that of conventional Pt-loaded carbon black.