Dynamic tracking of photocatalytic oxidation of organic micropollutant by Raman spectroscopy over Aurivillius Bi3.4La0.6Ti3O12 nanocatalyst

The need to develop an approach to gather detailed molecular information occurring on catalytic surfaces and gain deeper understanding of the structure-reactivity relationship of nanocatalysts for rational design and improved performance is essential in catalysis. In this study, we report the dynamic tracking of the degradation of a recalcitrant diazenyl-based micropollutant over Aurivillius lanthanum-doped bismuth titanate nanoparticles (BLT NPs) by Raman spectroscopy. By leveraging this powerful analytical technique, rich structural information can be retrieved, including the adsorbed species, which can provide profound insight of the degradation mechanism. Our observations show significant asymmetrical broadening in the vibrational spectra particularly within the range of 1300 cm−1 to 1400 cm−1, which can be attributed to the photo-oxidation of diazenyl derivatives within their specific chemical environment at ambient condition. The results, supported by high-performance liquid chromatography and mass spectrometry, demonstrate the selective cleavage of the pollutant's C-N and N = N bonds, likely resulting in the formation of 4-nitroazobenzene as the predominant intermediate product. [Display omitted] •Bi3.4La0.6Ti3O12 nanocatalyst was prepared via microwave-assisted hydrothermal method followed by calcination.•XRD confirmed a predominant orthorhombic phase and high crystallinity of the synthesized Bi3.4L0.6Ti3O12 nanoparticles.•The nanocrystals exhibited a Bi:La atomic concentration ratio of ~6:1 as revealed by XPS quantification.•Optical absorption reveals ~2.75 eV indirect band transition, beneficial to charge transport and photon absorption.