Engineering heterostructured Co0.7Fe0.3@Co doped leaf-like carbon nanoplates from dual metal-organic frameworks for high-efficiency oxygen reduction reaction in microbial fuel cell

Abstract

Microbial fuel cell (MFC) satisfies the needs of power generation and pollutants removal but still requires active electrocatalysts to accelerate cathodic oxygen reduction reaction (ORR). Metal-nitrogen-carbon materials (M − NCs) derived from Prussian blue analogues (PBAs), known for low cost and high yield, fail with satisfactory surface structure and their intrinsic activity requires to be further improved. Here, a MOF@MOF precursor (Co-ZIF-L@CoFe PBA-1, MOF: metal-Organic framework) is skillfully fabricated by utilizing two-dimensional (2D) leaf-like cobalt-based zeolitic-imidazolate framework (Co-ZIF-L) as the mother MOF to give birth to cobalt iron Prussian blue analogue (CoFe PBA) by adjusting reaction time and solvents with a ligand exchange method. After carbonization, Co-ZIF-L@CoFe PBA-1 transforms into a leaf-shaped carbon nanoplate with heterostructured CoFe alloy and Co (Co 0.7 Fe 0.3 @Co-NC-1), which exhibits outstanding ORR activity and high MFC performance (2486 ± 56 mW m -2 ) compared with Co-NC and Co 0.7 Fe 0.3 -NC derived from Co-ZIF-L and leaf-like CoFe PBA, respectively. The interfacial Co 0.7 Fe 0.3 @Co efficiently optimizes electronic structure for fast electrons transfer and the porous carbon matrix provides desirable surface structure for oxygen transfer, synergistically triggering a high ORR activity. Our work offers new insights for controllable preparation of PBAs-based dual-MOFs precursors and provides a feasible avenue for enhancing the activity of PBAs-based M − NCs catalysts. • Co-ZIF-L gives birth to Co-Fe PBA through a ligand exchange method. • The amount of Co-Fe PBA on Co-ZIF-L can be adjusted by reaction time and solvents. • The ORR activity is attributed to the integration of dual-MOF precursor. • The maximum power density of Co 0.7 Fe 0.3 @Co-NC-1 air cathode is 2486 ± 56 mW m 2 .