The Preparation of Z-Scheme Cu₂O-(rGO-TiO₂) Photocatalyst and Its Performance in Methyl Orange Degradation

An effective Z-scheme Cu₂O-(rGO-TiO₂) photocatalyst was successfully synthesized via a simple three-step approach for Methyl Orange (MO) removal under sunlight irradiation. Unlike the traditional heterojunction model, reduced graphene oxide (rGO) serving as conjunction enhanced Cu₂O-TiO₂ redox ability by increasing quantum efficiency. When loaded with 1% (mass fraction) rGO, the Z-scheme Cu₂O-(rGO-TiO₂) exhibited the best photocatalytic activity. The morphologies and optical properties of photocatalysts were characterized with a field emission scanning electron microscope (SEM), X-ray diffraction (XRD) and ultraviolet-visible spectrophotometer (UV-Vis DRS). The mechanism of Z-scheme system was probed via photoluminescence (PL) spectrum. The results showed that the thickness of Cu₂O-(rGO-TiO₂) composite film was about 32.24 μm. Cu₂O had a multi-faceted columnar structure with 111 crystal planes, which showed excellent photocatalytic activity. TiO₂ nanoparticles were evenly distributed on the surface of rGO that had a two-dimensional mono-layer fold structure. Cu₂O, TiO₂ and rGO successfully formed a Z-scheme photocatalytic system. The effects of different light sources and rGO loadings on Cu₂O-TiO₂ were studied respectively. The results showed that under simulated sunlight, the presence of rGO intermediary promoted MO removal efficiency and enhanced photocatalyst performance. The removal efficiency of MO was up to 58% in 2 hours. The effective Z-scheme system can be used for dye wastewater degradation and provide new ideas for environmental management.