Highly efficient photocatalytic activity of stable manganese-doped zinc oxide (Mn:ZnO) nanofibers via electrospinning method

Abstract

Manganese-doped zinc oxide (Mn:ZnO) nanofibers were synthesized using the electrospinning process. Structural, chemical, morphological and optical properties of the nanofibers were characterized and compared with undoped ZnO nanofibers. To investigate photocatalytic activity of nanofibers under the both UV and visible light, methylene blue (MB) was used as a representative dye pollutant. It was found that substitutional incorporation of Mn2+ and Mn4+ ions in ZnO resulted in the generation of additional energy levels within the band gap of ZnO. Furthermore, higher manganese incorporation resulted in smaller-sized Mn:ZnO nanoparticles with highly concave-convex structures, and consequently, an increase in surface area. Substitutional incorporation of the dopant ions and the resulting morphological variations provide better photocatalytic efficiency due to formation of a greater number of charge carriers and the corresponding delay in the recombination process. Among the studied dopant content, 0.5 at.% Mn:ZnO fibers was determined as the optimal composition and the degradation of MB can reach about similar to 100% after 90 min. UV light and similar to 35% after 100 min visible light illumination. The doped fibers displayed high stability and durability in the degradation tests, even after ten cycles. Mn:ZnO nanofibers are thus good candidate materials for photocatalytic applications with superior efficiencies and highly reusable properties.