Light-Assisted Synthesis of Hierarchical Flower-Like MnO2 Nanocomposites with Solar Light Induced Enhanced Photocatalytic Activity

We have demonstrated a novel solution chemistry route for the synthesis of nanoscale hierarchical flower-like MnO2 through a light-assisted decomposition of a manganese precursor over the surface of a clay nanotube. By tuning the reaction conditions, we have successfully synthesized δ-MnO2 flowery nanostructures comprising assemblies of intersected nanosheets and subsequently studied their photocatalytic activity for the degradation of organic dyes under natural sunlight irradiations. The crystallographic phase dependent photocatalytic activity of MnO2 nanocomposites has also been carried out toward the photodegradation of dyes, indicating δ-MnO2 nanostructures possess higher catalytic efficiency compared to α-MnO2. The underlying mechanism demonstrates the formation of reactive oxygen species, which in turn facilitate the degradation of dyes and also substantiates that there is no need of any supplementary oxygen sources during photodegradation. The outstanding performance of the hierarchical δ-MnO2 nanocomposites, together with the convenient fabrication method, represents an alternative and environmentally benign route to develop heterogeneous photocatalyst for the degradation of refractory pollutants. Thus, these new insights will shed light in the practical applications of heterogeneous catalysts for environmental remediation through wastewater treatment in a greener approach.