Synthesis, Characterization, and Application of Gadolinium-Doped ZnO:Au Nanocomposite as Nanophotocatalyst for the Efficient Degradation of Malachite Green Dye Under UV Irradiation

The present study focuses on the synthesis of efficient nano photocatalysts (pure and gadolinium-doped zinc oxide: gold nanocomposites) for the degradation of malachite green dye in polluted water. The synthesis of nanocomposites was achieved by the less time-consuming sonochemical method under ambient laboratory conditions. The synthesized nanocomposites were characterized by various spectroscopic techniques, namely X-ray diffraction (for structural and phase analysis), field emission scanning electron microscopy (for morphological studies and average particle size determination), and energy dispersive X-ray spectroscopy. Optical studies were done with UV–vis absorption spectroscopy and photoluminescence spectroscopy to determine the suitability of nanocomposites as nanophotocatalysts. The synthesized nanocomposites were employed for the degradation of malachite green dye under UV irradiation. The dependence of degradation efficiency on pH, concentration of dye, and nanocomposites was also studied, along with the reusability of nanophotocatalyst. Due to the presence of gadolinium as a dopant and gold nanoparticles, the synthesized ZnO-based nanocomposites are found to be the most efficient photocatalysts for the degradation of malachite green dye in basic conditions under UV irradiation.