Pd-Nanoparticles@layered double hydroxide/reduced graphene oxide (Pd NPs@LDH/rGO) nanocomposite catalysts for highly efficient green reduction of aromatic nitro compounds

Abstract

A facile chemical method was developed to fabricate well-dispersed, approx. 5 nm sized Pd-nanoparticles (Pd NPs)-deposited ZnAl-LDH/rGO nanocomposite (Pd NPs@LDH/rGO) as a highly efficient and stable catalyst for the reduction of aromatic nitro compounds. The nanocomposite substrate of ZnAl–(CO₃²⁻) LDH was prepared through an in situ process in the pre-dispersed GO solution. The successive ion exchange of intercalated CO₃²⁻ ions by Cl⁻ and PdCl₄²⁻ produced ZnAl–(PdCl₄²⁻) LDH. Pd NPs-deposited ZnAl-LDH/rGO was obtained by chemical reduction of Pd²⁺ ions to Pd⁰ using hydrazine hydrate as a reducing agent. The Pd NPs@LDH/rGO nanocomposite exhibited excellent heterogeneous catalytic activity towards the green reduction of aromatic nitro compounds to their corresponding amino compounds. The reaction was performed in an aqueous medium at ambient condition. This highly efficient catalyst is applicable for successful aromatic amine synthesis using various substituents. Moreover, the catalyst can be reused for eight successive runs with significant recycling stability.