Green hybrid photocatalyst containing cellulose and γ–Fe₂O₃–ZrO₂ heterojunction for improved visible-light driven degradation of Congo red

In the present study, we aimed to investigate the photocatalytic behavior of a novel bimetal-biopolymer nanocomposite of cellulose/γ–Fe₂O₃–ZrO₂ that was efficiently synthesized using a simple sol-gel method for photocatalytic applications. The photocatalysts were characterized by UV–visible diffuse reflectance spectrophotometry (DRS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer‒Emmett‒Teller (BET); the optical properties were determined by UV–visible spectrophotometry. Nano-ZrO₂ significantly decreased the optical bandgap of nano-γ–Fe₂O₃ from 4.90 eV to 2.28 eV at the γ–Fe₂O₃:ZrO₂ ratio of 1:1. Although the effect of nanocellulose on the energy bandgap of γ–Fe₂O₃–ZrO₂ heterojunctions was insignificant, the impact of nanocellulose on the photocatalytic degradation of Congo red increased from 80.0% to 98.5% in 30 min, and the maximum degradation value was obtained at the nanocellulose:Fe₂O₃–ZrO₂ ratio of 1:1. These results showed that the cellulose/γ–Fe₂O₃–ZrO₂ nanocomposite demonstrated a higher photodegradation efficiency of Congo red under visible light than γ–Fe₂O₃–ZrO₂, nano-γ–Fe₂O₃, and nano-ZrO₂. Briefly, our results confirm that the cellulose/γ–Fe₂O₃–ZrO₂ nanocomposite shows good photocatalytic activity toward the degradation of Congo red pollutants and can be a suitable candidate for various eco-friendly environmental applications.