Decoupling Layer Metal-Organic-Frameworks via Ligand Regulation to Achieving Ultra-Thin Carbon Nanosheets for Oxygen Reduction Electrocatalysis

Abstract

2D imidazole MOFs are considered to be ideal carbon precursors for oxygen reduction reaction owing to their adjustable ligand components and durable coordination mode. Due to the massive electron delocalization in the lamella, the conjugative effect among 2D MOFs layers immensely restrict the exposure of catalytic sites after carbonization, which makes decoupling layer extremely important on the premise of ensuring activity. Herein, atomic thickness ultra-thin zinc-imidazole MOFs precursor were fabricated through bottom-up ligand regulated strategy to achieve the aim of lamellar decoupling. The introduction of heterologous ligands excite stable delocalized electrons, resulting in decreasing interlayer force of 2D zinc-imidazole MOFs precursor. Subsequent salt template-supported ammonia pyrolysis assisted the MOFs-derived carbon sheets to grow along the transverse direction and optimize pore size distribution as well as doping nitrogen type. The MOFsderived carbon sheets demonstrated increasing mesopores and fringe graphitic N which could significantly promote the mass transfer and electron transfer speed during oxygen reduction reaction. Additionally, the obtained ultra-thin carbon delivered outstanding onset potential (0.98 V vs. RHE) and durability (retaining 91% initial current after 12000s of operation), showing tremendous commercial prospects in sustainable energy.