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.