Synthesis and Characterisation of ZnO/Ag Nanocomposites Prepared via Green Method Using Pineapple Peel Extract for Photocatalytic Enhancement in Degrading Methylene Blue Dye Solutions

Photocatalytic is one of the technological developments of renewable materials in overcoming water pollution due to industrial waste treatment. In this study, photocatalytic observations were carried out with a methylene blue (MB) degradation approach using zinc oxide and silver (ZnO/Ag) nanocomposites (NCs) which were enhanced by a new green synthesis in the form of pineapple peel extract (Ananas comosus) as a bio-stabiliser. The amount of Ag was varied by 5%, 10% and 15%. UV-Vis spectroscopy (UV-Vis), X-ray diffrection (XRD) and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) spectroscopy were analysed to study the optical properties, structure, morphology and composition of the samples. The characterisation results show that the absorption peak occurs in the 359 nm to 368 nm region with a band gap energy of 2.96 eV to 3.00 eV. Based on the XRD pattern, a hexagonal wurtzite structure was obtained with a crystal size of 18.37 nm. The particle morphology shows a flower-like shape with an average diameter of 60 nm. The EDX spectrum confirmed the elemental content of Zn, oxygen (O) and Ag. The photocatalytic activity showed that 10% ZnO/Ag was able to optimally degrade MB (10 ppm) with a reaction rate constant of 0.0091 min−1. Therefore, ZnO/Ag NCs were proven to be able to degrade dyes faster than pure ZnO.