Superior electrocatalytic ORR performance of Melaleuca Leucadendron L barks derived hierarchical porous carbon with abundant atom-scale vacancies and multiheteroatoms

Abstract

Biomass feedstocks from agriculture and forestry usually possess unique isometric microstructures that are used as potential renewable precursors to synthesize hierarchically porous carbon materials for energy-conversion applications. Herein, the powders of Melaleuca leucadendron L. barks (MLBs) impregnated with a hydrogen bonded complex (HBC) were carbonized to prepare CoBN-doped porous carbon (CBNC) as oxygen reduction reaction (ORR) electrocatalysts. The microstructure, porous texture and compositions of the as-obtained CBNC samples and their intermediates were characterized by small-angle neutron scattering (SANS) and other techniques. The lamellar structure of MLBs and the HBC strategy endowed the as-obtained CBNC with a unique porous texture, large specific surface area (1041 m2 g−1) and uniformly distributed heteroatoms of Co, B and N. The introduction of Co species in the precures is beneficial to improving the formation of atomic defects. The CBNC sample obtained at the optimized conditions exhibited a half-wave potential (E1/2) of 0.83 V and a kinetic current density (jk) of 9.73 mA cm−2 as well as a robust durability and methanol tolerance in the alkaline electrolyte; its overall ORR properties were highly superior to Pt/C (jk = 8.2 mA cm−2, E1/2 = 0.82 V). This novel approach offers a feasible way towards producing high-performance ORR electrocatalysts from biomass wastes.