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Broad-spectrum heterogeneous 1 T/2H MoSe2 homojunction nanosheets were prepared using single-step solvothermal process. The 1 T and 2H phase ratios in the homojunction could be controlled by adjusting the amount of NaBH4. Moreover, the presence of 1 T phase in the 1 T/2H MoSe2 increased the absorption ability of MoSe2 and accelerated electron transport, which greatly enhances the photocatalytic degradation activity under broad-spectrum range. Radical trapping experiments indicated that ·OH and ·O2− radicals are the main active species of methylene blue degradation. Combined with the results of photocatalytic activity and band structure, the photocatalytic mechanism of the 1 T/2H MoSe2 was proposed. [ABSTRACT FROM AUTHOR]

Although TiO 2 is a wide band gap semiconductor, it demonstrates photodegradation activity under visible light irradiation after dye sensitization. Compared with esterification between the surface hydroxyl group of TiO 2 and the carboxylic group of dyes, electrostatic interaction between TiO 2 and dye shows better photosensitized performance. In this work, Bi/Al co-doping anatase titania (Ti 1-x Bi 2x/3 Al 2x/3 O 2 (0 ≤ x ≤ 0.3)) is designed to enhance the electrostatic interaction. The effect of Al ions is to enhance the solubility of Bi3+ into titania nanocrystals. A new band gap is generated after high concentration of Bi element doping, which not only promotes the absorption of visible light, but also improves the utilization of photogenerated carriers. Based on the results of transmission electron microscopy, light absorption, photodegradation activity and density functional theory calculations, it is found that bismuth dopant is the electron capture site. It first accumulates electrons through photocatalytic degradation reaction to enhance electrostatic adsorption between the catalyst and the positively charged dye molecules, and finally realizes high-efficiency photosensitization degradation of Rhodamine B. In addition, the sensitized titania has excellent photodegradation recyclability. [Display omitted] • Bi and Al co-doped titania is designed to improve electrostatic interaction. • The addition of Al ions enhances the solubility of Bi3+ into titania. • Bismuth dopant is the electron capture site. • The sensitized titania has excellent photodegradation recyclability. [ABSTRACT FROM AUTHOR]

Surface defects have a significant effect on the photocatalytic reaction of Bi 4 Ti 3 O 12 , but the mechanism is unclear. In addition, when surface defects and highly exposed facets exist at the same time, which factor plays the main role in photocatalytic activity is also controversial. Herein, it is found that Bi 4 Ti 3 O 12 with adjustable concentrations of surface defects and percentage of exposed {001} facets can be prepared by using titania of different crystal types and sizes as raw materials, which is extremely beneficial for exploring the above problems. The photocatalytic activity of Bi 4 Ti 3 O 12 nanosheets with surface defects and exposed {001} facets was the same as that of Bi 4 Ti 3 O 12 nanosheets with surface defects alone (about 72.5% of photodegradation levofloxacin under 10 min of simulated sunlight irradiation). Based on the experimental results and density functional theory calculations, the influence mechanism of surface defects was deeply studied. The surface defects resulting from partial exfoliation of the external (Bi 2 O 2)2+ layers changed band structure of Bi 4 Ti 3 O 12. More importantly, surface defects with high concentration became hole trapping sites, which was conducive to the faster participation of holes in the photocatalytic oxidation process. [Display omitted] • Bi 4 Ti 3 O 12 with surface defects and exposed {001} facets was prepared. • The surface defects resulted from partial exfoliation of (Bi 2 O 2)2+ layers. • The enhanced photocatalytic performance was determined by the surface defects. • Surface defects with high concentration served as hole trapping sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • The MoIn 2 S 4 /CQDs composite photocatalyst was prepared for the first time. • The few-layer porous structure of MoIn 2 S 4 /CQDs was induced by anhydrous citric acid. • Efficient photocatalytic degradation of MB and other pollutants by the MoIn 2 S 4 /CQDs composite. • The photocatalytic reaction mechanism for the MoIn 2 S 4 /CQDs composite was proposed. Ternary metal chalcogenides as promising photocatalysts and introducing carbon quantum dots (CQDs) as a dopant to enhance their photocatalytic activity. In this study, MoIn 2 S 4 and MoIn 2 S 4 /CQDs composite photocatalysts were successfully synthesized utilizing an in-situ hydrothermal method, in which citric acid served as both the carbon source and surfactant. Among the prepared catalysts, the MoIn 2 S 4 /CQDs composite photocatalyst with the optimal ratio (MoIS/CQDs-1.0 g) exhibited the highest photocatalytic performance, achieving a removal rate of 94.4 % for methylene blue (MB) after 60 min of simulated solar illumination. The superior performance was primarily attributed to the upconversion photoluminescence effect of CQDs, which enhanced the light absorption of MoIn 2 S 4. Also, the few-layer configuration of MoIn 2 S 4 as a matrix possessed numerous active sites to significantly minimize the aggregation of CQDs. Furthermore, the CQDs acted as electron acceptors and transport centers, inhibiting the rapid recombination of photogenerated carriers and accelerating electron transfer. Additionally, through trapping experiments and electron paramagnetic resonance (EPR) tests, the primary active species responsible for photocatalytic degradation was identified as superoxide radicals (·O 2 –). Based on these findings, a possible photocatalytic mechanism for MoIS/CQDs-1.0 g was proposed. This study provided a novel, stable and efficient MoIn 2 S 4 modified with CQDs photocatalyst for water treatment. [ABSTRACT FROM AUTHOR]

This study explores the photocatalytic activity of oxygen-deficient Bi 2 MoO 6 photocatalysts with exposed {001} crystal planes, utilizing a combined approach of experiments and Density Functional Theory (DFT) to investigate enhanced catalytic performance to unravel the underlying mechanisms. The unique interlayer structure of Bi 2 MoO 6 semiconductor facilitates the construction of surface oxygen vacancies (SOVs) on the {001} crystal plane. However, its further photocatalytic applications are limited by the inherent photogenerated electron recombination and lack of active sites. In order to improve the performance of photocatalytic reactions, a systematic study was conducted on the exposure of {001} crystal faces in Bi 2 MoO 6 crystals under hypoxia induced by chloride ions (Cl-). After 30 min of visible light irradiation, Bi 2 MoO 6-4 (with the addition of 1 mmol sodium chloride in Bi 2 MoO 6) sample showed good photocatalytic degradation activity towards Rhodamine B (RhB), reaching 99.24 %, which is 1.67 times higher than pure Bi 2 MoO 6. Furthermore, the transient photocurrent value of Bi 2 MoO 6 -4 is about 1.32×10−7A, which is about twice that of Bi 2 MoO 6 -1. The above results can be attributed to the synergistic effect of SOVs induced by Cl- and {001} crystal planes in Bi 2 MoO 6 , while the {001} crystal surface has been proven by DFT to accelerate surface charge transfer and enhance molecular oxygen activation. This study highlights the advantages of regulating crystal faces exposure in improving photocatalytic activity and provides a promising strategy for designing other Bi based photocatalysts for environmental remediation. [Display omitted] • Cl− boosts the SOVs construction on {001} facets in Bi 2 MoO 6. • Synergistic promotion to degrade Rhodamine B for BMO by using SOVs and crystal plane engineering. • Synthetizing SOVs in the [Bi 2 O 2 ]2+ layer of BMO and effectively improve the optimization path of photogenerated carriers. • The charge transfer mechanism is validated by performing DFT calculations. [ABSTRACT FROM AUTHOR]

The photocatalytic activity of Bi 4 Ti 3 O 12 is limited by the lack of active sites and rapid carrier recombination. In this work, the problems mentioned above are effectively solved by using a dual functional CuS load on the surface of Bi 4 Ti 3 O 12. The CuS can be used as electron trapping sites to play a role as a cocatalyst, and form p-n junction with the Bi 4 Ti 3 O 12 under irradiation through the properties of p-type semiconductor. The dual functionality of CuS effectively promotes carrier separation and enhances the photocatalytic degradation activity. The photocatalytic rate of Bi 4 Ti 3 O 12 with optimal loading amount of CuS is ∼1.8 and ∼2.7 times as high as that of the Bi 4 Ti 3 O 12 and the CuS, respectively. The photocatalytic mechanism of the Bi 4 Ti 3 O 12 –CuS system is investigated in detail. • CuS can be used as electron trapping sites to play a role as a cocatalyst. • CuS form p-n junction with Bi 4 Ti 3 O 12 under irradiation through the properties. • The dual functionality of CuS effectively promotes carrier separation. [ABSTRACT FROM AUTHOR]