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• Biochar as a low cost and efficient carrier can alleviate the phenomenon of agglomeration of CdSe QDs. • The introduced biochar increases the active site and inhibits the recombination of photogenerated electron-hole pairs. • Biochar can improve the contact efficiency between tetracycline and photocatalyst. • CHC-3 photocatalyst has good visible light catalysis and can photodegrade 73.1% tetracycline in 80 min. In this paper, a simple in-suit method was used to load CdSe quantum dots (QDs) onto HTC (abbreviated as Hydrothermal biochar, HTC) to form CdSe/HTC composites. Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy were used to detect and analyze the surface valence and composition of CdSe/HTC composites. The photocatalytic degradation activity was judged by photodegrading tetracycline (TC). Compared with pure CdSe quantum dots, the best photocatalytic degradation efficiency of CdSe/HTC complex containing 15% HTC was 73%, which was attributed to the high carrier transport efficiency of HTC and the inhibition reorganization of photogenerated electron-hole pairs. More importantly, the hydrothermal biochar used in this paper was extracted from waste biomass and had the characteristics of economy, environmental protection and high utilization rate, and was in line with the basic viewpoint of sustainable use of resources. [ABSTRACT FROM AUTHOR]

To completely utilize the high redox ability of photo-induced charge carriers. Here, a Z-scheme photocatalyst of TiO 2 QDs/Bi 12 TiO 20 (TBT) composites with TiO 2 QDs fragment attached to the surface of Bi 12 TiO 20 (BTO) was prepared and the photocatalytic activity was evaluated by degradation of gatifloxacin (GF). The optimal photocatalytic performance of TBT displayed 3 times higher than bare BTO. The improved photocatalytic performance was ascribed to the effective separation of the charge carriers between TiO 2 QDs and BTO via the direct Z-scheme heterojunction. Such a strategy for the construction of Z-scheme TBT composites for removal of organic pollutants, proving new insights into design photocatalyst. • A TiO 2 quantum dots fragment was prepared and covered on the surface of Bi 12 TiO 20. • A Z-scheme heterojunction was formed between TiO 2 QDs and Bi 12 TiO 20. • The TOQs played as the sensitizer to increase the photocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract In this work, a simple method to load of g-C 3 N 4 quantum dots (CN QDs) onto Bi 2 Ti 2 O 7 (BTO) microsphere with the amount of CN QDs (3, 7, 10 and 15%). The photocatalyst was used for the treatment of water pollutants under visible-light illumination, which proved that CNBTO composites showed improved photocatalytic activity matched up to pure BTO. Reformation of BTO with CN QDs enhanced the light assimilation capacity, and promoted the isolation of photo-induced electron-hole pairs. The trapping experiments and ESR were announced the holes (h+) and superoxide oxide (O 2 −) played the key role, and the relative mechanism of the photocatalytic process was proposed. Meanwhile, the effects of CN QDs content, pH and initial pollutant concentration on the removal efficiency of ciprofloxacin (CIP) were studied. Results showed that the CN QDs loaded on BTO presented higher photocatalytic efficiency, and an optimum value for the dosage of photocatalytic in pH 8.0. Graphical Abstract The g-C 3 N 4 quantum dots modified Bi 2 Ti 2 O 7 microsphere for enhancing separation efficiency of electron-hole pairs. Unlabelled Image Highlights • The CN QDs have superior electron transfer ability and enriched light harvesting. • The CN QDs were coupled with Bi 2 Ti 2 O 7 microsphere have exhibited enhanced photocatalytic activity. • The CN QDs extends the light absorption of Bi 2 Ti 2 O 7 microsphere. [ABSTRACT FROM AUTHOR]

Abstract Many recent advances in constructing green metal-free materials have opened new possibilities in catalysis. To explore and enhance the photocatalytic performance of g-C 3 N 4 quantum dots (CN QDs), the metal-free materials of CN QDs embedded in the h-BN was successfully synthesized by calcination the mixture of melamine and h-BN. The studies proved the CNBN has appeared red-shift due to the quantum size effect and 2D h-BN. The CN QDs were embedded into the h-BN could not only facilitate the separation and transfer, but also the h-BN terminated with OH groups could act as active sites, thus enhanced the photocatalytic performance. Moreover, this work may pave the way for the application of CN QDs and fabricate 2D h-BN composites for green metal-free materials in another field. Graphical abstract A free-metal composites for environmental pollution treatment. Unlabelled Image Highlights • A metal-free materials were synthesized by the one-pot green procedure. • The composites were exhibited red-shift for increasing light absorption. • The efficiency of electrons separation and transfer enhanced the lifetime of active species. • The OH groups acted as active sites further improved the photocatalytic performance. [ABSTRACT FROM AUTHOR]