Ag nanoparticles decorated on Co3O4-C derived from ZIF-67: a recyclable catalyst for highly efficient reduction of nitrophenols

Silver-based nanostructured composites as effective and stable catalysts were successfully designed as the catalyst to reduce the nitrophenols in aqueous solution at room temperature in the presence of NaBH4. The Co3O4-C composites with regular morphology and adjustable components derived from ZIF-67 in an air atmosphere at various temperatures (270, 300, and 350 degrees C) were chosen as a favorable platform to support silver nanoparticles. The acquired silver-based nanocatalyst (Ag/Co3O4-C) exhibited excellent catalytic performance towards the hydrogenation of nitrophenols (2-NP, 3-NP, and 4-NP). The calculated rate constant (K-app) towards the reduction of 4-NP followed the order: Ag/Co3O4-C-300 (0.70 min(-1))>Ag/Co3O4-C-270 (0.58 min(-1))>Ag/Co3O4-C-350 (0.46 min(-1)). Ag/Co3O4-C-300 possessed the highest catalytic activity with no induction time during the reaction. What is more, Ag/Co3O4-C-300 could reduce 2-NP and 3-NP with the rate constant of 0.936 min(-1) and 0.391 min(-1), respectively. The catalytic activity was higher that many other metal-based nanocomposites. The excellent catalytic performance was mainly attributed to the abundant active sites on the surface, and the interfacial synergistic effect between Ag and Co3O4-C, which had a potential driving force for the hydrogenation reaction. In addition, the catalyst remained active even after recirculation experiments. The Ag-based nanocomposites can be expected to be applied in industrial applications.