Boosting the photocatalytic performance of Ag 2 CO 3 crystals in phenol degradation via coupling with trace N-CQDs

A Review on Carbon Quantum Dot Based Semiconductor Photocatalysts for the Abatement of Refractory Pollutants

Photocatalysis is a green approach frequently utilised to eliminate a variety of environmentally hazardous refractory pollutants. Accordingly, the modification of semiconductor photocatalysts with Carbon Quantum Dots (CQDs) is of great importance for the treatment of such pollutants due to their attractive physical and chemical properties. CQDs are a perfect candidate to handle photocatalysts of high-performance since they operate as co-catalysts and as visible light harvesters. The higher separation rate of electron-hole pairs in the photocatalytic system is attributable to better photodegradation efficiency. This review classifies CQD based photocatalysts as pure, doped and composite materials and discusses the specific advantages of CQDs in visible light-driven photocatalysis. In this work, the versatile roles of CQDs in CQD-based photocatalytic systems are thoroughly discussed and s u mmarised.

Fabrication and characterization of ZnTiO3/Zn2Ti3O8/ZnO ternary photocatalyst for synergetic removal of aqueous organic pollutants and Cr(VI) ions

Highly efficient photocatalysts have great development prospects in wastewater treatment, especially in the degradation of organic pollutants and reduction of inorganic heavy metal ions. Herein, a Z-scheme ZnTiO₃/Zn₂Ti₃O₈/ZnO ternary photocatalyst was prepared by the solvothermal-calcination method and the influence of the content of tetrabutyl titanate precursor and different reaction temperature on the crystal phase structures, photoelectrochemical properties and photocatalytic activities of the samples were investigated. Due to its unique Z-scheme structure and suitable band gap position, which is favorable for the efficient migration and separation of photo-generated electrons and holes and the improvement of photocatalytic redox reaction capability, the samples show excellent performance for the degradation of organic pollutants and reduction of heavy metal Cr(_VI) ions. Based on a series of characterization analyses, a possible Z-scheme photocatalytic mechanism is proposed. This work provides a simple preparation method for fabrication of multivariate heterojunction photocatalyst for degradation of organic pollutants and removal of heavy metal ions.

Biomass-derived Carbon Quantum Dots for Visible-Light-Induced Photocatalysis and Label-Free Detection of Fe(III) and Ascorbic acid

Visible-light-driven photocatalysts prepared using renewable resources are crucial but challenging to develop for the efficient degradation of organic pollutants, which is required to solve ever-increasing water deterioration issues. In this study, we report a visible-light-responsive photocatalyst for the efficient degradation of methylene blue (MB) as a model pollutant dye. Green-emissive carbon quantum dots (CQDs) were synthesized from pear juice via a facile, scalable, one-pot solvothermal process. The as-synthesized CQDs exhibit superior photocatalytic activity under visible-light irradiation owing to their efficient light absorption, electron transfer, and separation of photogenerated charge carriers, facilitating ~99.5% degradation of MB within 130 min. A possible mechanism for the photocatalysis is proposed on the basis of comprehensive active species trapping experiments. Furthermore, the CQDs were used in a specific sensitive assay for Fe(III) and ascorbic acid (AA), even with interference from other metal ions. The fluorescence emission of CQDs was "turned off" specifically upon binding of Fe(III) and "turned on" with AA. The prepared CQDs represent efficient photocatalysts and fluorescent probes that are not restricted by toxicity, cost, or lack of scalability.

Modification strategies for enhancing the visible light responsive photocatalytic activity of the BiPO4nano-based composite photocatalysts

The present issues related to environmental purification have led to a great need for the development of a superior oxidation process to solve the life-threatening problem. The use of the BiPO₄nanomaterial in photocatalysis is one of the best methods for the treatment of wastewater due to its less harmful nature.

An overview of recent progress on noble metal modified magnetic Fe3O4 for photocatalytic pollutant degradation and H2 evolution

Noble metal modified magnetic Fe₃O₄ catalysts for photocatalytic pollutant degradation and H₂ evolution are reviewed.

Facile Hydrothermal Synthesis of Z-Scheme Bi2Fe4O9/Bi2WO6 Heterojunction Photocatalyst with Enhanced Visible Light Photocatalytic Activity

An efficient binary Bi₂Fe₄O₉/Bi₂WO₆ Z-scheme heterojunction was fabricated through a facile hydrothermal route. The obtained Bi₂Fe₄O₉/Bi₂WO₆ displays high catalytic activity for rhodamine B (RhB) photodegradation, and 100% of RhB was photodegraded by Bi₂Fe₄O₉ (7%)/Bi₂WO₆ within 90 min, which is much better than that by pure Bi₂Fe₄O₉ and Bi₂WO₆. The effective photoinduced carrier separation, the broadened photoabsorption range, high oxidation capacity of hole, and the high reduction power of electron are in charge of the elevated catalytic activity because of the formed Z-scheme system. In addition, the effects such as pollutant concentration, pH, inorganic anions, and water sources exerted on photocatalytic performance were also investigated, and the results suggest that Bi₂Fe₄O₉/Bi₂WO₆ still possesses a high photocatalytic performance. The free-radical trapping experiments and electron spin resonance spin-trapping technology disclose that hole (h⁺), hydroxy radical (^•OH), and superoxide radical (^•O₂^-) are cardinal active radicals in the catalytic system. In terms of the above experimental analysis, a possible photodegradation mechanism of the as-fabricated photocatalyst is thoroughly elucidated. In addition, the possible RhB photodegradation pathway is also raised in the light of the analysis of liquid chromatography-mass/mass spectrometry. In addition, Bi₂Fe₄O₉/Bi₂WO₆ composite does not display dramatic reduction of the catalytic performance after five recycles. Thus, this study reveals that the as-obtained Bi₂Fe₄O₉/Bi₂WO₆ catalyst has a great prospect for the environmental purification.