Mechanically Activated Covalent Organic Framework as Metal Free Photocatalyst for Continuous Flow Fenton-like Degradation of Organic Pollutants and Hexavalent Chromium Reduction

A highly active photocatalyst is unveiled for the Fenton-like reactions in visible light. A metal-free covalent organic framework (COF) was highly active via a novel mechanical pulverization process. Under visible light, the activity of pulverized COF reached an apparent quantum yield of 41% for Fenton-like degradation. The exceptional performance is due to the conduction band's induced high excited electron density. The outstanding performance does not require pH adjustment by external means, unlike metal-based photocatalysts. The pulverized COF can be recycled up to five times. For industrial scale implementation, the photocatalyst outperformed in a continuous flow channel. The photocatalytic space-time yield (PSTY) was increased by 28 times over conventional batch photocatalysis. For successful chemical reactions, an exceedingly small amount of photocatalyst is required. Additionally, a very high photoreduction rate was also observed for hexavalent chromium, which was significantly better than the parent COF.