Green-synthesized ZnO/ZrO ₂ nanocomposite via chilli calyx extract: a potent solar-light photocatalyst for methylene blue degradation

In this study, we used a simple green solution combustion method to synthesize ZnO/ZrO2 nanocomposite mediated by green chilli calyx extract. The formation of synthesized material was characterised by XRD, FTIR, UV-Visible spectroscopy, SEM, EDX and TEM. The average particle size and band gap energy of the synthesized material are found to be 120 nm and 3.299 eV respectively. The photocatalytic efficiency of ZnO/ZrO2 nanocomposite was tested with Methylene blue dye degradation. The degradation is optimized by varying the light source, dye concentration, catalyst quantity, and pH. The synthesized ZnO/ZrO2 nanocomposite destroyed 99.6% of methylene blue under optimized conditions and the degradation follows pseudo first-order kinetics. Thermodynamic parameters are evaluated and experiments showed that the synthesized nanocomposite exhibits pH-dependent photocatalytic efficacy. The stability of the catalyst was examined for five cycles and both super oxide (•O2⁻) and hydroxyl radicals (•OH) are involving in the methylene blue degradation.