Nanocrystalline CaSb2O5(OH)2 and Ca2Sb2O7: Controlled syntheses, electronic structures and photocatalytic activity

A facile one-pot pH-dependent hydrothermal method has been developed in the controlled syntheses of CaSb2O5(OH)(2) and cubic Ca2Sb2O7 with large specific surface area. The as-obtained samples were characterized by X-ray diffraction (XRD), N-2-sorption BET surface area, UV-vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX) and Fourier transformation infrared spectroscopy (FT-IR). The electronic structures of CaSb2O5(OH)(2) and cubic Ca2Sb2O7 were determined by density functional theory (OFT) calculations. The photocatalytic performance of the as-prepared CaSb2O5(OH)(2) and cubic Ca2Sb2O7 was evaluated by the degradation of methyl orange (MO) and gaseous benzene. It was found that CaSb2O5(OH)(2) is more photocatalytic active than Ca2Sb2O7. A low crystal packing factor (PF) of CaSb2O5(OH)(2) is probably responsible for its superior photocatalytic performance as compared to that of cubic Ca2Sb2O7. (C) 2012 Elsevier B.V. All rights reserved.