Preparation and characterization of Ce-MOF/g-C3N4 composites and evaluation of their photocatalytic performance

In this study, unique hybrid structures were constructed between a Ce-based metal-organic framework (Ce-MOF)
and graphitic carbon nitride (g-C3N4) materials. In addition, the g-C3N4 materials used for these heterostructures
were prepared by five different methods, namely the conventional pyrolysis method, chemical exfoliation by a
strong acid, activation by an alkaline hydrothermal treatment, melamine-cyanuric acid supramolecular assembly
with a mechanochemical method, and by the solvothermally pre-treated method. The structural and morphological
properties of the resulting g-C3N4 sheets and their composites were characterized using scanning electron
microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), thermogravimetric
analysis-derivative thermogravimetry (TGA-DTG), diffuse reflectance UV–vis spectroscopy (UV–vis DRS) and N2
sorption-desorption isotherms (BET). Finally, the photocatalytic performance of the composites was determined
by following the photocatalytic degradation of methylene blue (MB) in an aqueous solution under UV–visible
light irradiation. It was found that the photocatalytic efficiency of the Ce-MOF/g-C3N4‒TS composite was
significantly higher than that of their counterparts (Ce-MOF or g-C3N4‒TS) for the photocatalytic degradation of
MB. When employing the composite, UV light-induced degradation of MB yielded an efficiency of 96.5% after
120 min for a dye solution containing 10 mg/L MB. This corresponds to a 5-fold or 2-fold improvement of the
rate constant (k) when compared to the Ce-MOF or g-C3N4, respectively.