Graphitic carbon nitride nanosheet/metal-organic framework heterostructure: Synthesis and pollutant degradation using visible light

The construction of binary and ternary heterojunctions has gathered attention in water remediation applications. Herein, g-C3N4, MIL-101(Fe), and MIL-101(Fe)/g-C3N4 binary composite were synthesized by in-situ growth of MIL-101(Fe) crystals along with the nanosheets of g-C3N4. The materials have been characterized by XRD, FTIR, SEM, EDS, DRS, PL, and BET/BJH. The highest degradation efficiency achieved using MIL-101(Fe)/g-C3N4 nanocomposite was 99.3% while the pristine g-C3N4 degraded only 40% of the pollutants by photocatalyst dosage = 0.005 g, pH = 4.8, and irradiation time = 90 min condition. This enhanced photocatalytic performance might be attributed to improved optical properties and quenched recombination rate of photogenerated electron-hole pairs utilizing the heterojunctions built during the synthesis process. The size of MIL-101(Fe) crystals diameters are in the range of 70–120 nm. The MIL-101(Fe)/g-C3N4/visible light/H2O2 systems obey the zero-order kinetics while the pristine g-C3N4 and Fe-MIL-101(Fe) obey second-order and first-order kinetics, respectively. It is obvious that the introduction of g-C3N4 nanosheets in the synthesis procedure of MIL-101(Fe), significantly affects the kinetics of RhB degradation in the presence of H2O2 under visible light. The pathway in which the photocatalytic reaction takes place was demonstrated to be the Z-scheme mechanism.