Bimetallic Co/Zn zeolitic imidazolate framework ZIF-67 supported Cu nanoparticles: An excellent catalyst for reduction of synthetic dyes and nitroarenes

In this study, a sub-class of microporous crystalline metal organic frameworks (MOFs) with zeolite-like configurations, i.e., zeolitic imidazolate frameworks of single node ZIF-67 and binary nodes ZIF-Co/Zn are used as the supports to develop Cu nanoparticles based nanocatalysts. Their catalytic activities are comparatively evaluated where Cu(x)@ZIF-Co/Zn exhibits better performances than Cu(x)@ZIF-67 in the reduction of synthetic dyes and nitroarenes. For instance, the Cu(0.25)@ZIF-Co/Zn catalyst shows an excellent reaction rate of 2.088 × 10⁻² s⁻¹ and an outstanding activity of 104.4 s⁻¹ g_cat⁻¹ for the reduction of methyl orange. The same catalyst also performs an exceptional catalytic activity in the hydrogenation of p-nitrophenol to p-aminophenol with the activity of 216.5 s⁻¹ g_cat⁻¹. A synergistic role of unique electronic properties rising from the direct contact of Cu NPs with the bimetallic nodes ZIF-Co/Zn, higher surface area of support, appropriate Cu loading and maintainable microporous frameworks with higher thermal and hydrolytic stability collectively enhances the catalytic activity of Cu(x)@ZIF-Co/Zn. Moreover, this catalyst shows excellent stability and recyclability, which can retain high conversion after reuse for 10 cycles.