Assembly of Mg-Mo-Al-Layered double hydroxides (LDHs) @ MoO42− and Its Synergistic Photocatalytic Degradation of Phenol in Wastewater

Graphical Photocatalysts enhance the ability to absorb low-energy photons due to the reduction of the band gap. Through the photocatalytic mechanism, it is known that when there is irradiation with light (hv) energy entering Mg 2+ -Mo 6+ -Al 3+ -MoO 4 2− -Layered double hydroxides (LDHs), highly active hole-electron pairs will be generated, and a large amount of ⋅OH will be generated after the reaction, which can completely oxidize the phenol in water into CO 2 and H 2 O. Mg 2+ -Mo 6+ -Al 3+ -MoO 4 2− -Layered double hydroxides (LDHs) materials were successfully prepared via a hydrothermal method by doping Mo 6+ in hydroxide laminates and inserting MoO 4 2− to replace the interlayer anions of LDHs materials. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectrometer (FTIRS) and ultraviolet-visible spectrophotometer (UV). The electronic density of states was calculated using the density functional theory (DFT) of Vienna Ab-initio Simulation Package (VASP). The effects of Mo 6+ and MoO 4 2− on the structure, morphology, electronic structure and photocatalytic performance of Mg 2+ -Al 3+ -LDHs were systematically studied. The conditions for phenol degradation by Mg 2+ -Mo 6+ -Al 3+ -MoO 4 2− -LDHs were optimized by single factor analysis and response surface methodology. The results show that the MoO 4 2− anion reduces the band gap width and thus enhances the absorption of low-energy photons. The interaction between cations and anions enhances the photocatalytic performance. When the dosage of Mg 2+ -Mo 6+ -Al 3+ -MoO 4 2− -LDHs was 0.03 g, the temperature was 40 °C and the visible light irradiation was 15 min, the removal rate of phenol reached 94.76 %.