Enhanced Photocatalytic Degradation of Rhodamine 6G Using Polypyrrole-ZnO Microcomposite Under UV Light Illumination

This work presents the synthesis of microcomposites of polypyrrole (PPy) and zinc oxide (ZnO) in varied weight percentages (1, 2, and 5 wt.%) for their potential in photocatalytic reactions. The properties of composites were investigated thoroughly using sophisticated analytical techniques, viz. X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible spectroscopy, thermogravimetric analysis, and Brunauer-Emmett-Teller analysis. The stretching vibrations of the Zn-O and N-H bonds corresponded to distinctive band frequencies at 480 cm−1 and 588 cm−1​, respectively, as indicated by the Fourier-transform infrared spectra analysis. Strong interactions between the ZnO and PPy matrix were revealed by the widening of these bands in the composites. The improved thermal stability of the microcomposites was demonstrated by thermogravimetric analysis. The accelerated carrier separation across the large interface between ZnO and PPy, together with the rapid dissipation of electrons, reduces the carrier recombination in the PPy effectively, thereby enhancing its photocatalytic property for PPy-ZnO microcomposites. The abundance of active sites is contingent upon surface area, while the recombination processes of electron-hole pairs are regulated by band gap energy. Among the microcomposites, PPy-2% ZnO displays a larger band gap energy than PPy-5% ZnO and a greater surface area compared to PPy-1% ZnO. Consequently, it boasts more active sites than PPy-1% ZnO and, simultaneously, mitigates recombination reactions more effectively than PPy-5% ZnO. These attributes collectively contribute to a heightened degree of photocatalytic reactions.