Active site-exposed Bi2WO6@BiOCl heterostructure for photocatalytic hydrogenation of nitroaromatic compounds

Abstract

Constructing heterostructured photocatalysts with highly exposed active sites proves to be an efficient strategy to improve the photocatalytic performance of bismuth-based photocatalysts. In this work, the active site-exposed Bi2WO6@BiOCl (BWO@BOC) heterostructure composites based on two bismuth-based materials were fabricated by an in situ growth method towards improving the photocatalytic hydrogenation of 4-aniline (4-NA) to p-phenylenediamine (PPD). The BWO@BOC exhibited enhanced photoactivity of 4-NA hydrogenation than pure BWO and BOC. The optimal BWO@BOC composites displayed the highest conversion rate of 4-NA to PPD up to 99.3% within 12 min, with an apparent reaction rate constant of 0.414 min-1, which is 3.3 times that of pure BOC. The photoactivity enhancement is mainly ascribed to the construction of a tight Z-scheme heterostructure with improved light harvesting properties and charge carrier transport efficiency, which were revealed by optical and photoelectrochemical characterizations, respectively. Furthermore, the products of the hydrogenation process were monitored by in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) to gain a better insight into the 4-NA hydrogenation mechanism.