Exploring the Influence of Carbonaceous Material on the Photocatalytic Performance of the Composites Containing Bi–BiOBr and P25 TiO₂ for NO_x Remediation

The Bi-BiOBr-P25 TiO₂ composite material exhibits high and synergistic improvements in the photocatalytic activity for nitrogen oxides (NO_x = NO + NO₂) removal. Herein, the influence of adding carbonaceous material to this composite, namely graphene (G), graphene oxide (GO), carbon nanotubes (CNT), and buckminsterfullerene (F) is explored; all at 1 wt%. Samples are synthesised using a one-pot solvothermal method. The structural and morphological properties, composition, and photocatalytic performance of all samples are examined using scanning electron microscopy, carbon-hydrogen-nitrogen elemental analysis, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray photoelectron spectroscopy, N₂ sorption at 77 K, photoluminescence spectroscopy, diffuse reflectance transient absorption spectroscopy), and photocatalytic testing against NO_x gas in accordance with ISO protocol (22197-1:2016). Among the studied carbonaceous composites, the composite including GO shows the highest performance toward NO_x remediation. For reactions in NO gas, it shows a combined higher NO_x removal rate (21.9%) than its parent materials P25 (8.7%), Bi-BiOBr (6.5%), and GO (0%). For reactions in NO₂ gas, it shows a higher NO_x removal rate (≈15%) than its parent materials P25 (≈10%), Bi-BiOBr (≈5%), and GO (0%).