Mechanism of Photocatalytic CO_2 Reduction by Bismuth-Based Perovskite Nanocrystals at the Gas-Solid Interface

摘要

We report here a series of nontoxic and stable bismuth-based perovskite nanocrystals (PeNCs) with applications for photocatalytic reduction of carbon dioxide to methane and carbon monoxide. Three bismuth-based PeNCs of general chemical formulas A_(3)Bi_(2)I_(9), in which cation A~(+) = Rb~(+) or Cs~(+) or CH_(3)NH_(3)~(+) (MA~(+)), were synthesized with a novel ultrasonication top-down method. PeNC of Cs_(3)Bi_(2)I_(9) had the best photocatalytic activity for the reduction of CO_(2) at the gas–solid interface with formation yields 14.9 μmol g~(–1) of methane and 77.6 μmol g~(–1) of CO, representing a much more effective catalyst than TiO_(2) (P25) under the same experimental conditions. The products of the photocatalytic reactions were analyzed using a gas chromatograph coupled with a mass spectrometer. According to electron paramagnetic resonance and diffuse-reflectance infrared spectra, we propose a reaction mechanism for photoreduction of CO_(2) via Bi-based PeNC photocatalysts to form CO, CH_(4), and other possible side products.