Robust iron-doped manganese oxide nanoparticles from facile fabrication to photo-catalytic degradation application of binary dyes mixture.

The manganese oxide (MnO 2 and iron-doped manganese oxide (Fe–MnO 2) nanoparticles (NPs) with reduced band gap (Eg) were fabricated through the co-precipitation process. They used to degrade Indigo Carmine (IC) and Rhodamine B (RB) binary mixture in an aqueous medium under solar light irradiation. From FT-IR, the twisting modes of the Mn–O bond and the stretching vibrations of the Fe–Mn–O 2 bond were confirmed from the peaks observed at 480 cm−1,584 cm−1,675 cm−1, and 900 cm−1, 1150 cm−1, and 1200 cm−1 respectively. The MnO 2 has an optical band gap of 3.2 eV, which was decreased to 3 eV in Fe–MnO 2. The zero charge (PZC) point was 8 for Fe–MnO 2 and 7 for MnO 2. The BET surface area for Fe–MnO2 was 398 m2/g, relatively higher than MnO2 particles, having a surface area of 384 m2/g. The average crystallite sizes calculated from Scherer formulae were 37 nm for MnO 2 and 31 nm for Fe–MnO 2 NPs. SEM confirmed the irregular morphology of the prepared particles. It was analyzed that agglomeration occurs in MnO 2 than the Fe–MnO 2. The maximum degradation of IC dye was 99%, and that of RB was 98% at the optimum conditions. The data were best fitted to second-order kinetics. [Display omitted] • Visible light-triggered and recyclable iron-doped manganese oxide (Fe–MnO 2) NPs as photocatalyst. • Morphological and structure tailoring studies was done through advanced techniques. • Photocatalytic degradation of Indigo Carmine (IC) and Rhodamine B (RB) single and binary mixture. • Response surface methodology (RSM) for optimization of degradation process. [ABSTRACT FROM AUTHOR]