Facile Synthesis of Metal–Organic Framework (ZIF‐11) and Ag NPs Encapsulated‐ZIF‐11 Composite as an Effective Heterogeneous Catalyst for Photodegradation of Methylene Blue

Facile synthesis of metal–organic framework based on zeolitic imidazolate (ZIF‐11) has been optimized to get a material with rho topology. For the first time AgNPs in various dosing amounts (using 150, 300 and 500 μL of its suspension in methanol) have been successfully encapsulated within ZIF‐11 matrix at room temperature using binary solvent (methanol and toluene) yielding novel multi‐core‐shell AgNPs@ZIF‐11 (AZ1, AZ2 and AZ3) composites. Encapsulation of AgNPs (particle size: 11.76 ± 2.3 nm) has been confirmed by TEM and ultraviolet diffuse reflectance spectroscopic (UV‐DRS) analysis. The lowering of band gap of ZIF‐11 from 4.36 to 4.21 eV indicates the micro‐environment of AgNPs within ZIF‐11 framework, which has also been ensured by XPS analysis. ZIF‐11 and AgNPs@ZIF‐11 composites are highly stable up to 500 °C under air and N 2 atmosphere. It has been found that AZ1 composite exhibits excellent photocatalytic activity (almost 100% degradation) toward MB (1.6 mg/L) at pH ≥ 8. Further, various factors such as loading amount of AgNPs (150, 300 and 500 μL suspension in methanol), amount of catalysts (5 mg, 10 mg and 15 mg) and concentration (1.6 mg L −1 , 3.19 mg L −1 and 6.38 mg L −1 ) of methylene blue (MB) dye during photodegradation experiments have been investigated. The capacious achievement of AZ1 composite is its reusability and recyclability; it can be reutilized up to three cycles with the same efficiency (100%) while under fourth and fifth cycle, it can degrade off 92.12% and 72.75% MB, respectively. AgNPs may act as a mediator to promote the quick transfer of photo‐induced electrons and electron–hole pairs separation in ZIF‐11. This work opens a new type of easily fabricated core‐shell composites utilizing ZIF‐11 for wastewater remediation process.