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 (O-center dot(2)-) 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 O-center dot(2)- formation but also provides interesting insights to explain the degradation dynamics based on the respective band positions in the nanocomposite.