A novel magnetic AgVO₃/rGO/CuFe₂O₄ hybrid catalyst for efficient hydrogen evolution and photocatalytic degradation

A superior semiconductor material with efficient charge separation and easy reuse could be a promising route for efficient photocatalytic hydrogen evolution and pollutant degradation. AgVO₃ is one of the best visible light active materials which has attracted much attention for several biological and environmental applications. In the aim of enhancing its stability and recyclability a novel AgVO₃/rGO/CuFe₂O₄ heterojunction was prepared by hydrothermal method for hydrogen generation (H₂) and 4-nitrophenol (4-NP) degradation as well. The composite was well characterized by XRD, SEM, HR-TEM, XPS and VSM. The morphological images suggested the rod shaped AgVO₃ and irregular shaped CuFe₂O₄ are unevenly distributed on reduced graphene oxide (rGO) layers. The hydrogen evolution results indicated that the composite showed around 8.937 mmol g^-1h^-1 of H₂ generation which was ∼2.3 times and ∼9.2 times higher than pure AgVO₃ (3.895 mmol g^-1h^-1) and CuFe₂O₄ (0.96 mmol g^-1h^-1) respectively. The 4-NP degradation efficiency of the prepared composite was observed as 94.7% (k = 0.01841 min^-1) which is much higher than the AgVO₃ (66.3%) and CuFe₂O₄ (38.2%) after 4 h of irradiation. The higher efficiency could be attributed to the heterojunction formation and faster charge separation. The radical trapping results indicated that the •OH, O₂•- and photogenerated h⁺ are the main species responsible for efficient activity. The AgVO₃/rGO/CuFe₂O₄ heterojunction showed 49.6 emu/g of saturation magnetization and confirms that it could be easily separated with an external magnet, and showed 85.3% of degradation efficiency even after 6 recycles which indicated its higher stability and recyclability. Thus, our study provides new insight into hydrogen generation and phenol degradation using AgVO₃ based recyclable composites.