Trapping oxygen in hierarchically porous carbon nano-nets: graphitic nitrogen dopants boost the electrocatalytic activity

Abstract

Rational control in both the chemical structures of nitrogen dopants and the mechanical structure in the mesoscale is the key point for optimizing the electrocatalytic activities of carbon nanocatalysts. Here we report the fabrication of N-doped carbon nano-nets (denoted g-N-MM-Cnet) with precise dopant distribution at graphitic sites and multiple-scale pore dimensions via supramolecular assemblies of block copolymer P123. The enriched graphitic nitrogen dopants, high surface area (1947 m² g⁻¹) and microporous–mesoporous bimodal nanopores in g-N-MM-Cnet make it an excellent bifunctional electrocatalyst for oxygen evolution and reduction reactions to construct rechargeable and ultra-stable (cycling lifetime: 491 h) two-electrode alkaline zinc–air batteries with a high energy density of up to 866.4 W h kg_Zn⁻¹ at 5 mA cm⁻².