Construction of CaTiO3 nanosheets with boron nitride quantum dots as effective photogenerated hole extractor for boosting photocatalytic performance under simulated sunlight

Herein, titanate-based perovskite CaTiO3 nanosheets were successfully designed via boron nitride quantum dots (BNQDs) to fabricate CaTiO3/BNQDs catalyst. The as-fabricated composite catalysts were analysed by transmission electron microscope (TEM), scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), X-ray diffraction (XRD), UV-vis spectroscopy (UV-DRS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) techniques. SEM-Mapping analysis showed that the boron and nitrogen elements dispersed well over the CaTiO3 surface which was useful for building electronic channels for rapid transport of photo-induced charge pairs. TEM images verified the attachment of BNQDs around the surface of host CaTiO3 forming intimate interface while the distribution of chemical states was observed by XPS analysis demonstrating strong coupling effect between BNQDs and CaTiO3 through Ti-O-N and Ti-O-B bonds. Moreover, PL and light absorption properties enhanced with the quantum confinement effect of BNQDs. As expected, the photocatalytic degradation rate of CaTiO3/BNQDs was increased to k(app) = 0.015 min(-1) with optimum BNQDs loading, which was 2.31 times folder than that of bare CaTiO3 (0.006 min(-1)). The enhanced photocatalytic efficiency was observed for CaTiO3/BNQDs than pristine perovskite on account of formation of electron tapping sites, decreased band gap energy and hindered recombination rate. On the other hand, in the presence of H2O2, the degradation percentage increased from 88.5% to 92.1% at the end of 120 min of irradiation while 96.8% of TC was quickly degraded within 60 min after activating with peroxymonosulfate which created strong sulphate radicals. Radical trapping tests indicated that the photo-generated holes were the primary active species in the photocatalytic mechanism. Moreover, CaTiO3/BNQDs catalyst showed excellent stability in recycling tests. Besides, the possible degradation mechanism was proposed. This study shed light on the significance of BNQDs in the enhancement of the photocatalytic activities of titanate-based perovskite for effective degradation of tetracycline antibiotic in contaminated water.

Automated summary

In this study, titanate-based perovskite CaTiO3 nanosheets were successfully designed using boron nitride quantum dots (BNQDs) to create a CaTiO3/BNQDs catalyst. The as-fabricated composite catalysts were characterized using various techniques, and it was found that CaTiO3/BNQDs catalyst exhibited enhanced photocatalytic efficiency and stability, making it a promising material for degrading antibiotics in contaminated water.