Eco-friendly synthesis of Ag-ZrO2 nanocomposites for degradation of methylene blue

In this work, we have successfully synthesized ZrO2 nanoparticles (NPs) using Ficus benghalensis (FB) leaf extract via simple microwave-assisted method. Silver NPs were deposited on the surface of ZrO2 through photocatalytic reduction. The synthesized ZrO2 and Ag-ZrO2 photocatalysts were characterized through X-ray Diffraction (XRD), UV–Vis Diffuse Reflectance Spectroscopy (DRS), Fourier Transform-Infrared Spectroscopy (FT-IR), High-Resolution Transmission Electron Microscopy (HR-TEM), Photoluminescence (PL), and Brunauer–Emmett–Teller (BET) surface area. From the aforesaid characterization of the materials, it is revealed that synthesized Ag NPs are crystalline in nature with the face-centered cubic structure (FCC), while ZrO2 NPs have both monoclinic and tetragonal phases. TEM images indicate that both ZrO2 and Ag-ZrO2 nanocomposite have spherical shape with the particle size of 20 and 15 nm, respectively. The optical properties were obtained using UV–Vis DRS which showed a decrease in the band gap energy of ZrO2 due to surface plasmon resonance (SPR) effect of Ag NPs. A lower in PL intensity of Ag-ZrO2 compared to that of ZrO2 NPs confirms the suppression of recombination rate of excited electron–hole pairs ultimately resulted into high photocatalytic activity. BET analysis shows that all the nanocomposites have higher surface area than pure ZrO2. The pure ZrO2 and Ag-ZrO2 show the efficient photocatalytic activity towards the methylene blue (MB) and methyl orange (MO). Ag-ZrO2 (1.0 wt.%) shows 21% increment in photocatalytic activity as compared to pure ZrO2 within 160 min under UV–Vis light.