Enhancement of the photocatalytic performance and thermal stability of an iron based metal–organic-framework functionalised by Ag/Ag3PO4

Metal–organic-frameworks have been reported as potential photocatalyst candidates due to their high surface area and semiconductive behaviour, but due to their high charge recombination rate and low visible light harvesting efficiency their use as photocatalysts has remained a challenge. A promising strategy to overcome these shortcomings is the construction of hybrid nanocomposite photocatalysts which reduce the recombination of charge carriers and simultaneously enhance the light harvesting efficiency. Herein, we report the microwave-assisted design of a novel visible light active composite material consisting of an iron-based metal–organic-framework functionalised by Ag/Ag3PO4. The resulting composite material demonstrates that both Ag3PO4 and MIL-53(Fe) show improved charge separation involving a Z-scheme internal charge transmission mechanism via ‘Ag’ nanoparticles (Ag0 NPs). The high dispersion of Ag0 and Ag3PO4 NPs and their close contact with the MIL-53(Fe) matrix help to degrade the organic pollutants effectively under visible light due to their synergistic effects. The photocatalytic degradation of a hazardous sulfonated azo dye Ponceau BS was carried out under visible light irradiation and Ag/Ag3PO4/MIL-53(Fe) was found to exhibit the highest photocatalytic performance. In addition, thermogravimetric analysis reveals that functionalization of MIL-53(Fe) by Ag/Ag3PO4/increases the thermal stability of MIL-53(Fe) which is attributed to the strengthening of an organic linker attached to iron due to the interaction of Ag/Ag3PO4 with the framework. Scavenger experiments supported the proposed Z-scheme internal charge separation. Moreover, the reusability experiments clearly indicate the high stability of the catalysts.