Three dimension Ni/Co-decorated N-doped hierarchically porous carbon derived from metal-organic frameworks as trifunctional catalysts for Zn-air battery and microbial fuel cells

Development of noble metal-free catalysts with great electrocatalytic performance and stability is of importance for electrochemical energy conversion and storage devices. Herein, we reported the synthesis of trifunctional catalysts with three-dimension (3D) hierarchically porous nitrogen-doped carbon framework with Ni-Co dual metal-involving and carbon nanotubes growth derived from nickel metal-organic framework. The as-synthesized catalyst exhibited better oxygen reduction reaction performance under both neutral and basic conditions compared with commercial Pt/C catalysts. Under basic electrolyte, the oxygen evolution reaction performance of the synthesized catalyst was comparable to that of commercial IrO2 catalysts and reasonable hydrogen evolution activity was achieved compared with reported non-noble metal-based catalysts. The assembled microbial fuel cell using the as-prepared material as the air electrode exhibited a maximum power density of 1971.2 mW m−2 and could steadily operate for more than 250 h of feed period. Furthermore, the Zn-air battery fabricated with the obtained catalyst showed excellent power density and rechargeability, which were superior to that of a Zn-air battery using Pt/C/IrO2 as the air electrode. We anticipate that the results described here can provide a new idea for design of multifunctional electrocatalysts for energy conversion and storage devices.