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 .

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