Catalytic Activity of Size Tailored Gold Nanoparticles for the Reduction of Environmental Pollutant, 4-Nitrophenol: A Greener Approach

In the present study, we targeted to synthesize size-dependent gold nanoparticles (Au NPs) using aqueous leaves extract of Actinodaphne madraspatna Bedd (AMB) both as reducing and stabilizing agents. The different sized Au NPs were effortlessly prepared by varying the concentration of AMB leaves extracts (2%, 3%, 4%). Characterization of synthesized Au NPs was performed by UV–Vis spectroscopy (UV–Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) and X-ray diffraction (XRD). The synthesized Au NPs using different concentrations of AMB leaves extracts were approximately polyhedral in shape as well as the particle size of AmAu2, AmAu3, and AmAu4 nanoparticles were calculated to be 80, 60 as well as 20 nm, respectively. Small-sized particles were obtained with a higher concentration of AMB leaves extract. The potential of the prepared Au NPs as catalyst was assessed by the reduction of organic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride (NaBH4) as a reducing agent and AmAu4 NPs has exhibited better catalytic activity evidenced by higher rate, when compared with gold NPs reported in the literature. From the study, different sized Au NPs were found to be suitable candidates in the environmental remediation of polluted water.