In-situ nitrogen-doped black TiO2 with enhanced visible-light-driven photocatalytic inactivation of Microcystis aeruginosa cells: Synthesization, performance and mechanism

• Published in: Applied catalysis. B, Environmental Vol. 272; p. 119019
• Main Authors: Zhou, Li, Cai, Min, Zhang, Xu, Cui, Naxin, Chen, Guifa, Zou, Guo-yan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.09.2020; Elsevier BV
• Subjects: Algae; Atmosphere; Bandgap narrowing; Catalytic activity; Chlorophyll; Deactivation; Degradation; Electromagnetic absorption; Energy gap; Free radicals; Inactivation; Metabolites; Microcystis; Microcystis aeruginosa; Nitrogen; Nitrogen impurity; Nitrogen-doped black TiO2; Organic matter; Oxygen; Oxygen vacancies; Photocatalysis; Photocatalysis mechanism; Precursors; Roasting; Synthesis; Titanium dioxide; Urea; Vacancies; Oxygen vacancies; Bandgap narrowing; Photocatalysis mechanism; Nitrogen impurity; Nitrogen-doped black TiO2
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119019

The intermediated band states exist in black nitrogen-doped TiO2 with N doping and oxygen vacancies, and reactive oxygen species produced under visible light irradiation to damage algae cells and degrade released organic matters. [Display omitted] •The calcination in an N2 atmosphere completed simultaneously N doping and oxygen vacancies production in nitrogen-doped black TiO2.•The urea addition as N precursor inhibited N incorporation and the oxygen vacancies production in nitrogen-doped black TiO2.•The sample nitrogen-doped black TiO2 with urea as N precursor showed higher photocatalytic activity to damage algae cells.•The process of inactivation algae cells included adsorption, damage of cells and release of DOM, and the degradation of DOM. A series of nitrogen-doped black TiO2 nanocatalysts were successfully synthesized by a one-step method. It is novel to find that calcination in an N2 atmosphere completed N doping and oxygen vacancies production simultaneously. In contrast, the urea addition as N precursor inhibited the nitrogen incorporation and the oxygen vacancies production. However, it is the sample using urea as N precursor that had the higher visible-light absorption, the narrower bandgap, the more efficient excited charges separation and higher degradation efficiency for removing chlorophyll-a in Microcystis aeruginosa algae cells. Mechanism exploration indicated that the intermediate energy states existed within the bandgap of TiO2, and O2− and OH were the dominant radicals responsible for algae cell damage and organic matter degradation. This research will provide additional insight into the roles of N precursors and a calcining atmosphere to improve the photocatalytic activity of nitrogen-doped black TiO2 for algae inactivation and metabolites degradation.