Monoclinic α-Bi2O3 photocatalyst for efficient removal of gaseous NO and HCHO under visible light irradiation

The investigation was focused on the visible-light-driven photocatalytic removal of gaseous NO and HCHO at typical indoor air concentration over synthetic alpha-Bi2O3. Monoclinic alpha-Bi2O3 was synthesized via calcination of hydrothermally prepared (BiO)(2)CO3 precursor at 500 degrees C for 4 h. The synthetic alpha-Bi2O3 samples were systematically characterized by XRD, SEM, FT-IR, and UV-vis diffuse reflectance spectra (DRS). The optical band gap energy of the resulting alpha-Bi2O3 was estimated to be 2.72 eV from the UV-vis absorption spectra. Comparing with the commercial Bi2O3 counterpart, the fabricated alpha-Bi2O3 showed superior visible-light-induced photocatalytic activity on degradation of nitrogen monoxide (NO) and formaldehyde (HCHO) at typical indoor air concentration. No obvious deactivation of synthetic alpha-Bi2O3 was observed during the prolonged photocatalytic reaction. This work suggests that the synthesized monoclinic alpha-Bi2O3 with suitable band gap and high activity is promising photocatalyst for indoor air purification. (C) 2010 Elsevier B.V. All rights reserved.