Manganese Trioxide with Various Morphologies: Applications in Catalytic Dye Degradation

Abstract

Hierarchical manganese trioxides (Mn 2 O 3 ) with different morphologies are prepared by thermal treatment of carbonate precursors synthesized using a facile and template-free hydrosolvothermal method. Various morphologies of Mn 2 O 3 have evolved as a function of precursor salts keeping the solvent system and temperature of synthesis intact. On hydrosolvothermal treatment, manganese carbonate with different microstructures is formed first and on subsequent calcination at 500°C, the carbonates are converted into manganese trioxide with the retention of the initial microstructure. While formation of Mn 2 O 3 microcubes is achieved with MnCl 2 and Mn (NO 3 ) 2 as precursor salts, microspheres and microflakes are obtained with Mn(OAc) 2 and MnC 2 O 4 precursors, respectively. The average microcrystal size varied from ∼ 10-20 (� 5) μm with somewhat high surface areas. The catalytic dye degradatin studies conducted on Mn 2 O 3 microcubes and microspheres in aqueous acidic mediums show rapid removal of dyes in the dark. While an aqueous acidic solution of methyl orange (MO) is decolorized in 2 min, more than 90 % of rhodamine B (RhB) and methylene blue (MB) are degraded within 50-60 min. Retention of catalytic activity after five cycles indicates their reusability and promise as simple binary oxide catalysts for wastewater treatment.[a] V.

Activation of O2 over three-dimensional manganese oxide nanoprisms under ambient conditions towards oxidative removal of aqueous organics

“…[33][34][35][36] In recent years, activation of O 2 over advanced catalytic materials under ambient conditions has been developed for the degradation of aqueous emerging contaminants and persistent organic pollutants. 37,38 For example, Wang and co-workers prepared a series of molybdatebased catalysts and hybrids for oxidative degradation of dyes using O 2 as the oxidant under ambient conditions. 39,40 Similarly, Mo involved supported, bimetallic and hybrid catalysts have been found to be efficient for O 2 activation under mild conditions recently.…”

MnCo2O4/Mn2O3 Nanorod Architectures as Bifunctional Electrocatalyst Material for Rechargeable Zinc–Air Batteries

“…Nucleation and growth kinetics, as well as intermediate-phase stability, can all have an impact on obtaining multiple phases in the final product. The following equations describe the reactions that occur during hydrothermal treatment − normalN normalH 2 − C O − normalN normalH 2 + 3 H 2 normalO → 2 normalN normalH 4 + + normalH normalC normalO 3 − + normalO normalH − normalM normaln 2 + + normalH normalC normalO 3 − + normalO normalH − → normalM normaln normalC normalO 3 + H 2 normalO 4 normalM normaln normalC normalO 3 + O 2 → 2 Mn 2 O 3 + 4 normalC normalO 2 normalC normalo 2 + + normalH normalC normalO 3 − + normalO normalH − → C o ( …”

“…Nucleation and growth kinetics, as well as intermediate-phase stability, can all have an impact on obtaining multiple phases in the final product. The following equations describe the reactions that occur during hydrothermal treatment − …”