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/Cx 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.