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 Co 2 P embedded in nitrogen-doped carbon nanoframework (Co 2 PNC-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 Co 2 PNC-NF. The electrochemical measurements revealed that the active carbon cathode modified by Co 2 PNC-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 Co 2 P can accelerate the ORR by boosting the cracking of OOH* group. Therefore, the Co 2 PNC-NF could be applied as an economical and efficient electrocatalyst in MFC to replace noble metal catalyst.