Fast Formation of N/Co Codoped Porous Graphene from Seed Husk Via Low-Temperature Molten Salts for Effective Oxygen Reduction Reaction

Abstract

Porous carbon nanomaterials derived from waste biomass have attracted great attention as high-performance non-precious metal electrocatalysts for oxygen reduction reaction (ORR). However, fast and large-scale conversion of porous carbon nanocatalysts with adjustable hole structure at low-temperature is still a huge challenge. Here, we proposed a fast and facile strategy to obtain non-metal and transition metal codoped porous graphene with tunable hole structure from waste seed husk via an improved low-temperature molten salt method using triple KCl/LiCl/ZnCl2 system in a short time (1 hour). The synergetic effect of tunable porous structure and codoped non-metal/transition metal elements can effectively enhance the ORR activity and long-term stability of carbon atoms in graphene. Specially, the prepared PG-600-N,Co catalyst (yield of 75%) shows a large specific surface area, sufficient micropores/mesopores structure and equally distributed N/Co elements, resulting in the excellent catalytic activity, long-term stability and methanol tolerance for ORR in alkaline media. More importantly, the PG-600-N,Co catalyst remains 97.1% of initial current density after a chronoamperometric response test of 65,000 s, which is much better than commercial Pt/C catalyst. Our work offers a feasible pathway for the massive and green synthesis of regulated codoped porous graphene as low-cost and efficient catalyst for ORR in energy conversion fields.

Keywords: porous graphene, low-temperature molten salt, electrocatalyst, oxygen reduction reaction, waste biomass