Aqueous/solid state Zn-air batteries based on N doped graphdiyne as efficient metal-free bifunctional catalyst

Abstract The undesirable electrocatalytic activity, durability and cost of cathode catalyst are main obstacles of rechargeable zinc air batteries (ZABs). Here, the stable operated aqueous ZABs and solid state ZABs are fabricated firstly with N-doped graphdiyne (GDY) as efficient metal free bifunctional catalyst. Benefiting from the uneven charge density caused by the coexistence of sp-, sp2- hybridized C atoms and pyridinic N, the abundant reaction interface and mass transmission channels provided by plentiful pores, N-doped GDY shows high catalytic performance. The as-prepared catalyst endows aqueous ZAB with high open circuit voltage of 1.54 V, lower polarization level than commercial Pt/C or IrO2, and especially long-time stability for 300 h (450 cycles). Density functional theory calculations results also confirm the better catalytic activity of pyridinic N than graphite N and amino-N in GDY nanostructure, since it renders the adjacent C atoms positively charged most effectively. This study provides a new kind of effective and ultra-stable metal free bifunctional catalyst applied for ZABs, especially the solid-state ZAB with excellent flexibility and variable shape for wearable electronics.