Abstract
Hydrogenated crystalline TiO2 with oxygen vacancy (OV) defect has been broadly investigated in recent years. Different from crystalline TiO2, hydrogenated amorphous TiO2−x for advanced photocatalytic applications is scarcely reported. In this work, we prepared hydrogenated amorphous TiO2−x (HA-TiO2−x) using a unique liquid plasma hydrogenation strategy, and demonstrated its highly visible-light photoactivity. Density functional theory combined with comprehensive analyses was to gain fundamental understanding of the correlation among the OV concentration, electronic band structure, photon capturing, reactive oxygen species (ROS) generation, and photocatalytic activity. One important finding was that the narrower the bandgap HA-TiO2−x possessed, the higher photocatalytic efficiency it exhibited. Given the narrow bandgap and extraordinary visible-light absorption, HA-TiO2−x showed excellent visible-light photodegradation in rhodamine B (98.7%), methylene blue (99.85%), and theophylline (99.87) within two hours, as well as long-term stability. The total organic carbon (TOC) removal rates of rhodamine B, methylene blue, and theophylline were measured to 55%, 61.8%, and 50.7%, respectively, which indicated that HA-TiO2−x exhibited high wastewater purification performance. This study provided a direct and effective hydrogenation method to produce reduced amorphous TiO2−x which has great potential in practical environmental remediation.
Highlights
Hydrogenated crystalline TiO2−x (C-TiO2−x ) has been extensively investigated owing to its full-spectra absorption and effective solar energy conversion, deriving from the selfdoped states created by oxygen vacancy (OV) and Ti3+ species [1,2,3]
The weakened intensity in diffraction peaks can be explained by long-range lattice disorder, which verified that amorphous TiO2 was generated on the Ti mesh surface, and in particular its concentration increased with the treatment time
Our results proved that OV disordered surface induced a narrow bandgap by introduced shallow states which was responsible for the low-energy photon absorption
Summary
Hydrogenated crystalline TiO2−x (C-TiO2−x ) has been extensively investigated owing to its full-spectra absorption and effective solar energy conversion, deriving from the selfdoped states created by OV and Ti3+ species [1,2,3]. TiO2 as a common type of titanium oxide has not been reported on after hydrogenation for its photoactivity utilization. In order to tailor more narrower bandgap and acquire more photons utilization, amorphous TiO2 should be considered as an ideal candidate for hydrogenation treatments, which could largely boost the photoactivity and bring about some original and significant physicochemical observations. Owing to its poor solar energy conversion and ineffective charge separation, amorphous. Hydrogenation with amorphous TiO2 inevitably calls for annealing or thermal hydrogenation, which
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