Tailoring the bandgap of Mn3O4 for visible light driven photocatalysis

Abstract

The photocatalytic activity of pure Mn₃O₄ and silver (Ag) modified Mn₃O₄ nanoparticles have been investigated. The nanoparticles were prepared by using co-precipitation technique. The structural analysis showed that the Ag modified Mn₃O₄ was successfully synthesized. For instance, a slight shift to lower angle of XRD pattern was observed after Ag doping. Morphological analysis revealed that the particles have an average size of 274 nm, 287 nm and 321 nm for pure, 1% and 3% Ag modified Mn₃O₄ respectively. The UV-Visible analysis indicated that the bandgap of Mn₃O₄ decreased with increased Ag content and the band gap is 1.4 eV with the 3% of Ag content. The spectra obtained from DRS were also evaluated through inverse logarithmic derivative method (ILD) to counter check the bandgap values. 3% Ag-modified photocatalysts exhibited the enhanced decolorization efficiency compared to pure Mn₃O₄ nanoparticles. The pseudo first order kinetic model is used to explain the photocatalytic kinetics of the photocatalyst. The rate constant values are 0.01/min, 0.017/min and 0.024/min for pure Mn₃O₄, 1% Ag and 3% Ag modified Mn₃O₄ nanoparticles, respectively.

Keywords: Manganese oxide; Methylene blue; Photo catalysis; Visible light.