NH₂-UiO-66 Coated with Two-Dimensional Covalent Organic Frameworks: High Stability and Photocatalytic Activity

The poor stability and low catalytic activity of NH₂-UiO-66 in basic solutions require the reactions to be conducted in acidic solutions, which seriously hinders its potential photocatalytic application. Herein, we report that NH₂-UiO-66 coated with two-dimensional covalent organic frameworks (COFs) via imine bond connection presents not only high photocatalytic activity but also high stability and adaptability to the solution environment. The NH₂-UiO-66/COF hybrid material was fabricated through the Schiff base reaction of NH₂-UiO-66 with 4,4',4″-(1,3,5-triazine-2,4,6-triyl)trianiline (TAPT) and 2,4,6-triformylphloroglucinol (TP). The hybrid material showed high stability in an alkaline environment, with only 4.7% of NH₂-UiO-66 decomposed after the photocatalytic reaction. The optimum photocatalytic H₂ evolution rate was 8.44 mmol·h^-1·g^-1 when triethanolamine was used as an electron-donating agent. The results presented here illustrate the possibility for effectively improving both the photocatalytic performance and stability of NH₂-UiO-66 by coupling with COFs.