The focus of this study is to develop and employ a barium hexaferrite/graphitic carbon nitride nanocomposite, abbreviated as BaFe/gCN NC, for photocatalytic degradation of Congo red (CR) under visible light illumination. Barium hexaferrite and graphitic carbon nitride were prepared using sol–gel and thermal polymerization methods to achieve an even distribution and good contact at the interface. The nanocomposite was then prepared through the sonication method. The properties of synthesized materials were confirmed by the examination of their physicochemical properties. By employing an X-ray diffractometer (XRD), the structure analysis of the synthesized materials provided a hexagonal form. It was also observed that the band gap of this composite was estimated to be 2.7 eV using UV–visible spectroscopy analysis. FTIR spectroscopy confirmed the vibrational modes along with the chemical structure and bonding present in the samples. The characteristics of BaFe/gCN nanocomposite reveal that the hexagonal grain boundary is probably distributed all over the surface of g-C3N4 nanosheets, as observed from high-resolution scanning electron microscopy (HR-SEM). It was confirmed from the XPS analysis that the elements and chemical states of BaFe/gCN NCs are present in the form of Ba 3d, Fe 2p, O 1s, N 1s, and C 1s. Finally, 50 mg of the produced material is degraded with the help of BaFe/gCN photocatalyst, removing 90% of CR dye at 10 mg/L initial dye concentration in 150 min. Moreover, the removal ability for CR by BaFe/gCN NC was maintained more than 88% during three test cycles. As a result of increased light absorption properties of BaFe/gCN and the prevention of electron and hole recombination, active oxygen species were produced, and hence the photocatalytic activity increases.

Barium hexaferrite nanoparticles embedded on graphitic carbon nitride for visible light photocatalytic degradation
    Abstract
    1 Introduction
    2 Methodology
        2.1 Materials
        2.2 Preparation of BaFe12O19
        2.3 Preparation of g-C3N4
        2.4 Preparation of BaFe12O19g-C3N4 nanocomposites
        2.5 Degradation experiment
        2.6 Characterization
    3 Results and discussion
        3.1 Structural analysis
        3.2 Functional group analysis
        3.3 SEM
        3.4 Bandgap analysis
        3.5 Oxidation state analysis
        3.6 Photocatalytic activity
        3.7 Recyclability
        3.8 Photocatalytic mechanism
        3.9 Charge transfer and separation
        3.10 Reduction reaction
        3.11 Oxidation reaction
    4 Conclusion
    Acknowledgements 
    References

• Shanmugapriya Dharani(Department of Electrochemistry, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602105, India)
• SaravanaVadivu Arunachalam(Department of Electrochemistry, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602105, India)
• S. Thanigaivel(Department of Biotechnology, Faculty of Science and Humanities, SRM Institute of Science and Technology, Tamil Nadu, Kattankulathur, Chengalpattu 603203, India)
• Saravanan Rajendran(Instituto de Alta Investigación, Universidad de Tarapacá, 1000000 Arica, Chile) Corresponding author
• Wei‑Hsin Chen(Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan, Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan, Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan)