CoFe₂O₄ decorated g-C₃N₄ nanosheets: New insights into superoxide anion mediated photomineralization of methylene blue

Graphitic carbon nitride (g-C₃N₄) based photocatalysts have recently gained much attention for environmental remediation. However, the correlation between constituent counterparts in g-C₃N₄ based nanocomposites as well as mechanistic understanding related to the reactive oxygen species (ROS) have not been discussed much. Herein, ascribing to the significant thermodynamic potential of surface charge transfer between their conduction bands, we present spinel cobalt ferrite (CoFe₂O₄) decorated g-C₃N₄ nanosheets for photocatalytic mineralization of methylene blue (MB). The ROS are investigated using electron spin resonance (ESR) spectroscopy and the results confirm the formation of superoxide anion radical (^[rad]O₂^-) as primary oxidant. Furthermore, UV–vis-NIR diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) analysis are utilized to plot alignment of energy levels against standard hydrogen electrode (SHE). The band diagram does not only support the ^[rad]O₂^- formation but also provides interesting insights to explain the degradation dynamics based on the respective band positions in the nanocomposite.