Fast and Facile Synthesis of Cobalt-Doped ZIF-8 and FeO/MCC/Cobalt-Doped ZIF-8 for the Photodegradation of Organic Dyes under Visible Light.

Co-doped ZIF-8 as a water-stable visible light photocatalyst was prepared by using a one-pot, fast, cost-effective, and environmentally friendly method. The band structure of ZIF-8 was tuned through the incorporation of different percentages of cobalt to attain an optimal band gap ( ) that enables the activation of ZIF-8 under visible light and minimizes the recombination of photogenerated charge carriers. A magnetic composite of Co-doped ZIF-8 was also synthesized to facilitate catalyst recycling and reusability through the application of an external magnetic field. Surface modification of magnetic FeO nanoparticles with microcrystalline cellulose (MCC) was used to reduce the level of agglomeration. The photocatalytic activities of Co-doped ZIF-8 (Co-ZIF-8) and FeO/MCC/Co-ZIF-8 were evaluated for the photodegradation of methylene blue (MB) under visible light irradiation from a 20 W LED source. Co-ZIF-8 showed considerably higher photocatalytic activity than pure ZIF-8, confirming the success of the doping strategy. Both Co20%-ZIF-8 and FeO/MCC/Co20%-ZIF-8 exhibited similar and remarkable photocatalytic activity under visible light (achieving 97% MB removal). The mechanism of photodegradation of MB by FeO/MCC/Co20%-ZIF-8 was studied, revealing a first-order degradation kinetics ( = 13.78 × 10 min), with peroxide and hole species as the predominant active reagents. The magnetic composite successfully displayed recyclability and reusability over multiple cycles with negligible reduction in MB photodegradation efficiency.