Palladium nanoparticles decorated on amine functionalized graphene nanosheets as excellent nanocatalyst for the hydrogenation of nitrophenols to aminophenol counterparts

Highlights: • Pd/GNS-NH2 nanocatalyst have been prepared and characterized in detail. • Pd/GNS-NH2 have been tested as a catalyst for the hydrogenation of nitrophenols. • Pd/GNS-NH2 has shown record catalytic activity for hydrogenation of nitrophenols. • Pd/GNS-NH2 has highly reusability performance for the hydrogenation of nitrophenols. • This work is the most comprehensive work for the hydrogenation of nitrophenols. -- Abstract: We reported the improved catalytic property of Pd (0) nanoparticles decorated on amine-functionalized graphene nanosheets (Pd/GNS-NH₂) for the hydrogenation of nitrophenol derivatives in the presence of NaBH₄ at moderate conditions. Pd/GNS-NH₂ nanocatalyst was synthesized by the deposition-reduction method. Sundry techniques such as ICP-OES, P-XRD, XPS, TEM, HR-TEM and EDX have been applied to explain the structure and morphology of the Pd/GNS-NH₂ nanocatalyst. The results show that the Pd (0) nanoparticles are perfectly dispersed on the surface of the GNS-NH₂ support material (d_mean = 1.38–2.63 nm). The catalytic activity of the Pd/GNS-NH₂ nanocatalyst was tested in the hydrogenation of nitrophenol derivatives in water in the presence of NaBH₄ as reductant and the excellent activity of nanocatalyst have been detected against 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,4,6-trinitrophenol derivatives with 116.8, 65.9, 42.8 and 11.4 min⁻¹ initial TOF values, respectively. Another important point is that the nanocatalyst has very high reusability performance (at 5th reuse between 71.5 and 91.5%) for the hydrogenation of nitrophenols. Finally, catalytic studies have been carried out at various temperatures to calculate the E_a, ΔH^≠ and ΔS^≠.