Green Synthesis of Gold Nanoparticles for Catalytic Reduction of 4-Nitrophenol and Methylene Blue for Sustainable Development

Unique structural features and wide applications of gold nanoparticles (GNPs) are inspiring researchers to develop biocompatible, reliable and cost-effective methods for their synthesis. Herein, a clean, eco-friendly and non-toxic method to obtain GNPs was developed by reducing and capping the liquid extract of stem of Lilium longiflorum and highlights the catalytic reduction of 4-nitrophenol (4-NP) and methylene blue (MB). The formation of GNPs was confirmed through the absorption peak at 535 nm in the UV-Vis spectra. TEM and HRTEM analyses reveal GNPs spherical morphology with an average size of 4.97 nm. SEM and EDX analyses further elucidate the spherical nature of GNPs and elemental composition. FTIR spectroscopy analysis demonstrates that the GNPs were coated with organic compounds, which prevent the nanoparticle from aggregation. GNPs exhibit remarkable efficiency in reducing 4-NP and MB. The catalytic efficacy of the synthesized GNPs was demonstrated through the enhanced reduction rates of 4-NP and MB, with rate constants of 1.50 min⁻¹ and 1.29 min⁻¹, respectively. This study develops a novel and eco-friendly technique for the synthesis of gold nanoparticles and opens possibilities for the green synthesis of other metal nanoparticles. The confirmed catalytic activity holds promise for a range of industrial applications and environmental sustainability.