Copper-based nanocatalysts for nitroarene reduction-A review of recent advances

Heterogeneous catalysts based on copper (Cu) nanostructures possess several advantages compared to other metallic nanocatalysts such as gold (Au), silver (Ag), platinum (Pt), and palladium (Pd). Various Cu based composite catalysts such as copper-graphene compounds, Co–Cu mixed spinel materials, Cu based Metal-Organic Frameworks (Cu-MOF), CuO-reduced graphene oxide (CuO-rGO) nanocomposites, copper chalcogenides, copper nanoferrites and mesoporous Cu₂O-CeO₂ nanospheres for the reduction of nitroarenes are reviewed in detail. It has been shown that Cu nanostructures, in combination with other materials such as 2D materials or MOFs, can offer a significant improvement in the catalytic performance compared to the bare metals in the nanoscale. Photocatalytic reduction of nitro aromatic compounds using copper chalcogenides such as CuS, CuInS₂ and other composite structures including Cu₂O, Ag/Cu₂O hybrids, Cu₂O-TiO₂ heterojunction are also addressed. Proposed reaction pathways, kinetics, and mechanism for the reduction of nitroarenes using various Cu based nanostructure are also reviewed comprehensively.