Sulfur and nitrogen dual-doped graphdiyne as a highly efficient metal-free electrocatalyst for the Zn-air battery

Sulfur and nitrogen dual-doped graphdiyne (NSGD) has been found to be a promising catalyst for oxygen reduction reaction (ORR) through a combination of density functional theory (DFT) calculation and the application of oxygen evolution reaction (OER) experiments. The DFT analysis suggests that adsorption characteristics are significantly altered by resulting nitrogen and sulfur doping, which in turn affect the ORR activity. In particular, the NSGD-800 catalyst exhibits an increased ORR half-wave potential of 0.754 V, with enhanced stability due to the synergy effect of N and S. Meanwhile, thanks to the unique acetylene-rich structure of graphdiyne to anchor metal oxides with strong d-π interactions, the activity and stability of com-RuO₂ for OER were significantly enhanced by mixing with NSGD-800. The zinc-air battery (ZAB) with NSGD shows a much higher peak power density (87.3 mW cm⁻²) and longer charge-discharge cycle stability compared with the ZAB with Pt/C, making it an excellent candidate air electrode for ZAB and other energy storage and conversion devices.