Co2P embedded in nitrogen-doped carbon nanoframework derived from Co-based metal-organic framework as efficient oxygen reduction reaction electrocatalyst for enhanced performance of activated carbon air-cathode microbial fuel cell

A kind of Co2P embedded in nitrogen-doped carbon nanoframework (Co2PNC-NF) synthesized from directly carbonized Co-based metal-organic framework (ZIF-67) combined with phosphorus was utilized in the microbial fuel cell (MFC) to modify the active carbon air-cathode for the first time. Various techniques involving XRD, FESEM, TEM/EDS, BET and XPS were used to characterize the microstructure, morphology and surface chemical composition belonging to as-synthesized Co2PNC-NF. The electrochemical measurements revealed that the active carbon cathode modified by Co2PNC-NF got reduced resistance and optimized catalytic behavior in oxygen reduction reaction (ORR) process. The optimized MFC had a high maximum power density reaching 2001 mW m(-2), increasing by 123% compared with the bare active carbon cathode MFC. This result showed that combination between transition-metals phosphide and heteroatom-doped carbon matrices was beneficial to the improvement of MFC performance. Moreover, density functional theory calculations indicated that the special structure of double Co site of 001 face of Co2P can accelerate the ORR by boosting the cracking of OOH* group. Therefore, the Co2PNC-NF could be applied as an economical and efficient electrocatalyst in MFC to replace noble metal catalyst.