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 heterostructureswere prepared by five different methods, namely the conventional pyrolysis method, chemical exfoliation by astrong acid, activation by an alkaline hydrothermal treatment, melamine-cyanuric acid supramolecular assemblywith a mechanochemical method, and by the solvothermally pre-treated method. The structural and morphologicalproperties of the resulting g-C3N4 sheets and their composites were characterized using scanning electronmicroscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), thermogravimetricanalysis-derivative thermogravimetry (TGA-DTG), diffuse reflectance UV–vis spectroscopy (UV–vis DRS) and N2sorption-desorption isotherms (BET). Finally, the photocatalytic performance of the composites was determinedby following the photocatalytic degradation of methylene blue (MB) in an aqueous solution under UV–visiblelight irradiation. It was found that the photocatalytic efficiency of the Ce-MOF/g-C3N4‒TS composite wassignificantly higher than that of their counterparts (Ce-MOF or g-C3N4‒TS) for the photocatalytic degradation ofMB. When employing the composite, UV light-induced degradation of MB yielded an efficiency of 96.5% after120 min for a dye solution containing 10 mg/L MB. This corresponds to a 5-fold or 2-fold improvement of therate constant (k) when compared to the Ce-MOF or g-C3N4, respectively.