Facile synthesis of mesoporous Cr₂O₃ microspheres by spray pyrolysis and their photocatalytic activity: Effects of surfactant and pyrolysis temperature

Abstract

Mesoporous Cr₂O₃ microspheres with improved pore structure were prepared by spray pyrolysis method. A precursor solution was nebulized into fine droplets containing chromium salt and cetyltrimethylammonium bromide (CTAB), which were then pyrolyzed to Cr₂O₃/C_x microspheres inside a tubular furnace, followed by post-heat treatment to eliminate the carbonaceous material. The produced Cr₂O₃ particles had a diameter of 0.5-1 um and their textural properties could be tuned by adjusting CTAB amount and pyrolysis temperature. The synthesized Cr₂O₃ microspheres had the highest surface area and pore volume of 52 m²g^-1 and 0.3 cm³ g^-1, respectively, which surpass those of Cr₂O₃ prepared using a conventional method such as thermal decomposition, hydrothermal reduction or wet chemical synthesis. The photocatalytic degradation of methyl orange dye (MO) was tested on the prepared Cr₂O₃ particles. It was determined that the spray pyrolysis-derived Cr₂O₃ exhibited greater photocatalytic activity than that of commercial TiO₂ and Cr₂O₃ particles prepared by the thermal decomposition of chromium salt.