Tris(triazolo)triazine-Based Covalent Organic Frameworks for Efficiently Photocatalytic Hydrogen Peroxide Production

Two-dimensional covalent organic frameworks (2D-COFs) have recently emerged as fascinating scaffolds for solar-to-chemical energy conversion because of their customizable structures and functionalities. Herein, two tris(triazolo)triazine-based COF materials (namely COF-JLU51 and COF-JLU52) featuring large surface area, high crystallinity, excellent stability and photoelectric properties were designed and constructed for the first time. Remarkably, COF-JLU51 gave an outstanding H₂O₂ production rate of over 4200 μmol g^-1 h^-1 with excellent reusability in pure water and O₂ under one standard sun light, that higher than its isomorphic COF-JLU52 and most of the reported metal-free materials, owing to its superior generation, separation and transport of photogenerated carriers. Experimental and theoretical researches prove that the photocatalytic process undergoes a combination of indirect 2e^- O₂ reduction reaction (ORR) and 4e^- H₂O oxidation reaction (WOR). Specifically, an ultrahigh yield of 7624.7 μmol g^-1 h^-1 with apparent quantum yield of 18.2 % for COF-JLU52 was achieved in a 1 : 1 ratio of benzyl alcohol and water system. This finding contributes novel, nitrogen-rich and high-quality tris(triazolo)triazine-based COF materials, and also designate their bright future in photocatalytic solar transformations.