Room temperature selective reduction of nitrobenzene to azoxybenzene over magnetically separable urchin-like Ni/Graphene nanocomposites

• An urchin-like Ni/Graphene nanocomposite was for selective reduction of nitroarenes into azoxybenzene.
• A 100% conversion and selectivity to the target product were observed with a turnover number of 36.2.
• The catalyst exhibits high stability and recyclability (93% conversion, 100% selectivity after the 4th reuse).
• Ni/Graphene nanocomposite is magnetically separable for catalyst recovery.

Magnetically recyclable Ni/Graphene (Ni/G) nanocomposites were synthesized via an in situ reduction growth process for selective reduction of nitroarenes into corresponding azoxybenzene at room temperature and at atmospheric pressure. Here, hydrazine hydrate (N2H4⋅H2O) is used as the reducing agent which generates harmless by-products such as N2 and water. The catalyst, when used under controlled reaction conditions, exhibits a 100% conversion and selectivity to the target product without the use of any external additives (turnover number 36.2). Under the optimized conditions, a variety of structurally different nitroarenes were selectively transformed to their corresponding azoxy products in high conversions. Furthermore, a high stability and recyclability of the catalyst were also observed under the investigated conditions (93% conversion, 100% selectivity after the 4th reuse).

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