Synthesis and characterization of mesoporous silica-MnO2 nanocomposite - An efficient nanocatalyst for Methylene blue degradation

In the present study, shell-type mesoporous silica-manganese dioxide (MPS-(MnO2)) nanocomposite was prepared and subsequently assessed for photodegradation of Methylene blue (MB) in synthetic solution under visible light. Electron micrographs show that MPS-(MnO2) composite was spherical and the average particle size was similar to 180 nm. Elemental composition analysis endorses the existence of Si, Mn and O in MPS-(MnO2) composite, and sharp X-ray diffraction pattern at (1 1 3) indicates the crystalline phase of MPS-(MnO2) nanocomposite. SiO2 doping decreased the band gap of MnO2 from 2.05 to 1.98 eV, which increased the visible light absorption of MPS-(MnO2) nanocomposite. In Nyquist plots, semicircle at high frequency area indicates that MPS-(MnO2) nanocomposite has high charge transfer rate compared with MnO2 and SiO2. Similarly, semi-oval cyclic voltammogram confirms the high specific capacitance of MPS-(MnO2) compared to bare MnO2. Under optimized conditions (30 mg/L initial MB concentration, catalyst dose 75 mg/100 mL and pH 9), the MPS-(MnO2) nanocomposite degraded 89.4% of MB from synthetic solution.

Automated summary

A shell-type mesoporous silica-manganese dioxide (MPS-(MnO2)) nanocomposite was prepared and studied for its photodegradation of Methylene blue (MB) in synthetic solution under visible light. SiO2 doping was found to decrease the band gap of MnO2, increasing the visible light absorption. Under optimized conditions, MPS-(MnO2) efficiently degraded 89.4% of MB from the synthetic solution.