Tunable Synthesis of Hematite Structures with Nanoscale Subunits for the Heterogeneous Photo-Fenton Degradation of Azo Dyes

Facile syntheses of branched hematite (α-Fe2O3) crystals with fine-tuning of their nanoscale subunit morphologies were reported. Starting from Prussian red and bisolvent systems with controlled temperature as the crucial parameters, fine-tuning of the nanoscale subunit morphologies in the context of controlling the anisotropic growth of branched α-Fe2O3 crystals was demonstrated. The systematic and optimized studies significantly improved the controlled synthesis of the hierarchical growth of nanoscale subunits, leading to the formation of branched dendritic leaflike (secD3D, tertD2D, and tertD3D) and hyperbranched (secS2D and hypB2D) α-Fe2O3 particles for their size-reduced variants used in photocatalysis. The kinetics of the photo-Fenton degradation of three azo dyes (chlorazol black, direct blue, and methyl orange) with five types of branched dendritic α-Fe2O3 particles were compared systematically.