Enhanced chemocatalytic reduction of aromatic nitro compounds by biosynthesized gold nanoparticles

• Green synthesis of Au nanoparticles using Salvadora persica stem extract.
• The synthesized Au nanoparticles were well dispersed, small size (10–30 nm) and spherical in shape.
• Effect of stem extracts concentration on the size, shape and dispersion of Au nanoparticles.
• The Au nanoparticles were screened for chemocatalytic reduction of 4-nitrophenol to 4-aminophenol.
• Effect of different amounts of AuNPs, and particle size, shape and dispersion on the chemocatalytic activity.

A novel and eco-friendly green procedure was developed for the synthesis of Au nanoparticles using stem extract of Salvadora persica. This plant stem extract provides a favorable environment for the formation of small size and well dispersed Au nanoparticles within 15–30 nm diameter. The Au nanoparticles were characterized by UV–vis spectroscopy, XRD, HRTEM, SEM, EDX and FT-IR. The particle size and morphology of Au nanoparticles were also investigated at different stem extract concentrations. The results showed that lesser the concentration of stem extract, spherical and small will be the size of Au nanoparticles. The present research indicated that the green synthesized Au nanoparticles can be used as an effective catalyst for the chemocatalytic reduction of 4-NP to 4-AP. Various factors i.e. catalyst amounts and particle size and shape that affect the chemocatalytic reduction of 4-NP to 4-AP were also studied. The results showed that Au nanoparticles synthesized at 15 vol.% extract's concentration have strong chemocatalytic activity and reduced 4-NP only within 3 min. It may be due to the single spherical shape and small size of Au nanoparticles.

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