HiGee strategy towards large-scale synthesis of soluble covalent organic frameworks

The scale-up synthesis of covalent organic frameworks (COFs) with uniform structure and properties is of great importance for their practical applications. Here, we proposed a facile way to massively produce phthalocyanine-like COFs (COF_BTC) via high-gravity intensified synthesis. Alcoholic solvent and basic catalyst were discovered synergically improved the formation of COF_BTC. High concentration and reaction temperature were beneficial for high production as well. The intensified mass and heat transfer at high-gravity promoted the scaling-up of COF_BTC with homogeneous structures and properties. A high space time yield of 305.9 kg∙(m³ D)⁻¹ was achieved for Fe-COF_BTC under optimized condition. The massively produced Fe-COF_BTC presented good solubility in alkaline and polar organic solvents, thus allow to process as homogeneous or heterogenous electrocatalyst for oxygen reduction reaction. The catalyst exhibited good performance of 0.79 V (vs. RHE, half-wave) and >95% recovery in homogeneous electroreduction of O₂ in 0.1 M KOH. A superior performance of 0.86 V was achieved by sol–gel-like processing of Fe-COF_BTC on carbon paper due to the enhanced conductivity. The scale-up soluble catalysts with uniform properties provide more opportunities for practical applications of COF_BTC.