Abstract
Black TiO2 with doped nitrogen and modified carbon (b-N-TiO2/C) were successfully prepared by sol-gel method in the presence of urea as a source of nitrogen and carbon. The photocatalysts were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, electron paramagnetic resonance (EPR), and UV-vis diffuse reflectance spectra (DRS). The doped nitrogen, introduced defects, and modified carbon played a synergistic role in enhancing photocatalytic activity of b-N-TiO2/C for the degradation of chlorophyll-a in algae cells. The sample, with a proper amount of phase composition and oxygen vacancies, showed the highest efficiency to degrade chlorophyll-a, and the addition of H2O2 promoted this photocatalysis degradation. Based on the trapping experiments and electron spin resonance (ESR) signals, a photocatalytic mechanism of b-N-TiO2/C was proposed. In the photocatalytic degradation of chlorophyll-a, the major reactive species were identified as OH and O2−. This research may provide new insights into the photocatalytic inactivation of algae cells by composite photocatalysts.
Highlights
Harmful algal blooms (HABs) have been a serious environmental disaster in eutrophic waters due to nutrient loading and climate change [1]
Much effort has been devoted to improving photocatalytic efficiency by narrowing its wide bandgap through element doping
The morphology and microstructure of 0.6 N are characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM)
Summary
Harmful algal blooms (HABs) have been a serious environmental disaster in eutrophic waters due to nutrient loading and climate change [1]. Microcystis aeruginosa is one of the most known harmful algae in natural waters. In view of the removal of Microcystis aeruginosa, the photocatalysis can be considered as one of the most optimal technologies to inactivate algae due to its low cost, high efficiency, and environmental friendliness [3,4]. Much effort has been devoted to improving photocatalytic efficiency by narrowing its wide bandgap through element doping. The nitrogen element has a similar characteristic to the oxygen in TiO2 , nitrogen doping is considered to be one of the most effective methods in narrowing the bandgap of TiO2 [8,9]. In order to improve the photocatalytic efficiency of doped TiO2 under visible light, engineering defects on the doped TiO2 was applied at the same
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