Continuous fabrication of hollow photocatalytic CNT/TiO2/calcium alginate microfibers via needle-based microfluidic device for environmental remediation in NO removal

NO is a common harmful air pollutant which leads to various environmental and health problems and needs to be addressed urgently. Herein, by combining sol-gel method and microfluidic approach, we successfully developed novel hollow alginate microfibers containing CNT/TiO 2 photocatalysts. The resulting fibers, with diameter of 1000 μm and adjustable wall thickness of 60-150 µm, were confirmed through microscope and SEM. The formation condition about various flow rate ratios of different phases was also investigated. Subsequently, various characterization methods including XRD, FT-IR and XPS were employed to investigate structural properties of prepared CNT/TiO 2 hybrid materials. Our findings indicate that the boosted absorption ability towards the visible light region, improved photo-generated electron transfer efficiency, as confirmed by UV-vis spectroscopy and electrochemical impedance respectively, mainly account for the enhanced photocatalytic performance in NO oxidation. The optimized CNT(10%)/TiO 2 microfibers exhibited the best NO removal efficiency of 44.3% under visible light, which is 1.59 times that of the pure TiO 2 . This study represents an interesting case for the combined preparation of CNT/TiO 2 /alginate microfibers for NO abatement. • Hollow microfibers with adjustable wall thickness containing carbon nanotube (CNT)/ titanium dioxide (TiO 2 ) photocatalysts were prepared through a need-based microfluidic device. • Optimal CNT/TiO 2 microfibers exhibited enhanced performance in the removal of NO about 44.3% and 53.9%, respectively, under visible and UV light. • Enhanced visible light absorption, improved separation efficiency of photo-generated electron-hole pairs, and narrowed energy band gaps could account for the great photocatalytic performance in NO removal.