Monoclinic α-Bi₂O₃photocatalyst 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 α-Bi2O3. Monoclinic α-Bi2O3was synthesized via calcination of hydrothermally prepared (BiO)2CO3precursor at 500 °C for 4 h. The synthetic α-Bi2O3samples were systematically characterized by XRD, SEM, FT-IR, and UV-vis diffuse reflectance spectra (DRS). The optical band gap energy of the resulting α-Bi2O3was estimated to be 2.72 eV from the UV-vis absorption spectra. Comparing with the commercial Bi2O3counterpart, the fabricated α-Bi2O3showed 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 α-Bi2O3was observed during the prolonged photocatalytic reaction. This work suggests that the synthesized monoclinic α-Bi2O3with suitable band gap and high activity is promising photocatalyst for indoor air purification.