Ultrafast photodegradation of textile industry dyes using efficient sulfide based ternary nanocomposites

We developed novel zinc-cadmium-bismuth sulfide (Zn-Cd-Bi₂S₃) and Zn-Cd-SnS nanocomposites to fabricate a heterojunction by an easy chemical technique to improve photocatalytic degradation of textile dye. Crystalline size and lattice parameter are analyzed using X-ray diffraction (XRD) spectrometer. The obtained strong diffraction peaks with various diffraction planes confirm the fabrication of a high crystal quality nanocomposite as well as the identification of its mixed crystal structure. The morphological information is studied using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (TEM). Due to its higher surface energy, the as-prepared nanocomposite displayed agglomeration by adjoining to tiny particles. The roughness of surface is studied by atomic force microscopy (AFM). Fourier transform-infrared spectroscopy (FT-IR) used to study about presence of organic functional groups on the surface of nanocomposite. Using UV-Visible and photoluminescence spectra, the impact of shifting the positions of Sn and Bi ions on the optical characteristics is investigated. Thermal property of the nanocomposite is studied by thermogravimetric-differential thermal analysis (TG-DTA) at air atmosphere. We examine and compared the photocatalytic activity of Zn-Cd-Bi₂S₃ and Zn-Cd-SnS nanocomposites for the crystal violet (CV) dye. Under the sun light irradiation Zn-Cd-Bi₂S₃ nanocomposite demonstrated a highest percentage of degradation (88.5%) within a short period (120 min). The obtained photocatalytic results indicate that the active radicals •O_2-, h⁺, and •OH- are favourable for the photocatalytic reaction. A possible photocatalytic mechanism for the dye degradation for the photocatalyst is proposed. Due to the narrow band gap, wide range of incident light captured by the heterostructure nanocomposite and the photogenerated electrons and holes is effectively separated in the Zn-Cd-Bi₂S₃.

A Comprehensive Review on Graphitic Carbon Nitride for Carbon Dioxide Photoreduction

Inspired by natural photosynthesis, harnessing the wide range of natural solar energy and utilizing appropriate semiconductor-based catalysts to convert carbon dioxide into beneficial energy species, for example, CO, CH₄ , HCOOH, and CH₃ COH have been shown to be a sustainable and more environmentally friendly approach. Graphitic carbon nitride (g-C₃ N₄ ) has been regarded as a highly effective photocatalyst for the CO₂ reduction reaction, owing to its cost-effectiveness, high thermal and chemical stability, visible light absorption capability, and low toxicity. However, weaker electrical conductivity, fast recombination rate, smaller visible light absorption window, and reduced surface area make this catalytic material unsuitable for commercial photocatalytic applications. Therefore, certain procedures, including elemental doping, structural modulation, functional group adjustment of g-C₃ N₄ , the addition of metal complex motif, and others, may be used to improve its photocatalytic activity towards effective CO₂ reduction. This review has investigated the scientific community's perspectives on synthetic pathways and material optimization approaches used to increase the selectivity and efficiency of the g-C₃ N₄ -based hybrid structures, as well as their benefits and drawbacks on photocatalytic CO₂ reduction. Finally, the review concludes a comparative discussion and presents a promising picture of the future scope of the improvements.

Novel S-scheme 2D/2D Bi4O5Br2 nanoplatelets/g-C3N5 heterojunctions with enhanced photocatalytic activity towards organic pollutants removal

Removal of organic pollutants and pharma products in waste water using semiconductor photocatalysts has gained huge interest among recent days. However, low visible light absorption, recombination rate of charge carriers and less availability of reaction sites are still major obstacles for the photocatalysis process. Herein, an in situ-forming Bi₄O₅Br₂ nanosheets decorated on the surface g-C₃N₅ were prepared via simple hydrothermal method under ambient temperature. The basic pH condition plays a vital role in growing for Bi₄O₅Br₂ nanosheets. Various characterization studies such as TEM, SEM, PL and UV-DRS studies confirmed the formation of close contact between the Bi₄O₅Br₂ and g-C₃N₅ nanosheets. The construction of Bi₄O₅Br₂ nanoplatelets/g-C₃N₅ nanocomposite increases the surface-active sites and improving the separation efficiencies of excitons, which is greatly influenced in the degradation of ciprofloxacin and bisphenol-A pollutants. Meanwhile, the flow of electrons from the layered structured graphite carbon of g-C₃N₅ which enables excellent electrical contact in the heterojunction. Besides, the main free radicals were determined as e^- and ^•O₂^-, and production level of free radicals were confirmed by radical trapping experiments. The possible degradation mechanism was proposed and discussed. Finally, this work provides a unique approach to in-situ preparation of heterojunction photocatalysts and demonstrates the prepared Bi₄O₅Br₂ nanoplatelets/g-C₃N₅ photocatalysts have great potential in the waste water management.

Recent advances in degradation of organic pollutant in aqueous solutions using bismuth based photocatalysts: A review

Today, a major concern associated with the environment is the water pollution occurred due to the introduction of variety of persistent organic pollutants and residual dyes from different sources (e.g., dye and dye intermediates industries, paper and pulp industries, textile industries, tannery and craft bleaching industries, pharmaceutical industries, etc.) into our natural water resources. Recently, advanced oxidation processes (AOPs) by photocatalyst have garnered great attention as a new frontier promising eco-friendly and sustainable wastewater treatment technology. Utilization of the photocatalytic technology efficiently is significant for cleaner environment. Bismuth based photocatalyst have aroused widespread attention as a visible light responsive photocatalyst for waste water treatment due to their non-toxicity, low cost, modifiable morphology, and outstanding optical and chemical properties. In this review, we have dealt with the research progress on bismuth-based photocatalysts for waste water treatment. However, it seems to give limitation over pristine photocatalysts such as slow migration of charge carriers, charge carrier recombination, low visible light absorption, etc., Various bismuth based photocatalyst and its modifications via doping, heterojunction, Z-scheme etc., are discussed in detail. Further, the strategies adopted to improve the photocatalytic activity of bismuth based photocatalyst to improve the waste water treatment (mostly drugs and dyes) are critically reviewed. Also, we have discussed the bacterial inactivation by bismuth based photocatalyst. Finally, the challenges and future aspects against bismuth based photocatalyst are explored for further research.

Recent advances in g-C3N4 composites within four types of heterojunctions for photocatalytic CO2 reduction

Studies of photocatalytic conversion of CO₂ into hydrocarbon fuels, as a promising solution to alleviate global warming and energy issues, are booming in recent years. Researchers have focused their interest in developing g-C₃N₄ composite photocatalysts with intriguing features of robust light harvesting ability, excellent catalysis, and stable performance. Four types of heterojunctions (type-II, Z-scheme, S-scheme and Schottky) of the g-C₃N₄ composites are widely adopted. This review aims at presenting and comparing the photocatalytic mechanisms, characteristics, and performances of g-C₃N₄ composites concerning these four types of heterojunctions. Besides, perspectives and undergoing efforts for further development of g-C₃N₄ composite photocatalysts are discussed. This review would be helpful for researchers to gain a comprehensive understanding of the progress and future development trends of g-C₃N₄ composite heterojunctions for photocatalytic CO₂ reduction.

Bi4NbO8Cl {001} nanosheets coupled with g-C3N4 as 2D/2D heterojunction for photocatalytic degradation and CO2 reduction

Photocatalytic activity is largely restricted by insufficient photoabsorption and intense recombination between charge carriers. Here, we first synthesized Bi₄NbO₈Cl nanosheets with {001} exposing facets by a molten-salt growth method, which shows largely promoted photocatalytic performance for the degradation of tetracycline (TC) and bisphenol A (BPA) in comparison with Bi₄NbO₈Cl particles obtained by solid-state reaction. The 2D/2D Bi₄NbO₈Cl/g-C₃N₄ heterojunction photocatalysts were then fabricated via high-energy ball-milling and post-sintering to realize intimate interfacial interaction. The photocatalytic activity of all the Bi₄NbO₈Cl/g-C₃N₄ composites largely enhances compared to Bi₄NbO₈Cl nanosheets and g-C₃N₄, also far exceeding the mechanically-mixed Bi₄NbO₈Cl nanosheets and g-C₃N₄. The impact of different reaction parameters on the photocatalytic degradation activities was investigated, including catalyst concentration, pH value and TC concentration. In addition, Bi₄NbO₈Cl/g-C₃N₄ also presents improved photocatalytic CO₂ reduction activity for CO production. The large enhancement on photocatalytic activity of Bi₄NbO₈Cl/g-C₃N₄ composites is owing to the synergistic effect of favorable 2D/2D structure and construction of type II heterojunction with intimate interfacial interaction, thus boosting the charge separation. The formation of type II heterojunction was evidenced by selective photo-deposition of Pt and MnO_x, which demonstrate that the reductive sites and oxidative sites are on Bi₄NbO₈Cl nanosheets and g-C₃N₄, respectively. This work may provide some insights into fabrication of efficient visible-light driven photocatalysts for environmental and energy applications.

Controlled Microwave-Assisted Synthesis of the 2D-BiOCl/2D-g-C3N4 Heterostructure for the Degradation of Amine-Based Pharmaceuticals under Solar Light Illumination

Designing efficient 2D-bismuth oxychloride (BiOCl)/2D-g-C₃N₄ heterojunction photocatalysts by the microwave-assisted method was studied in this work using different amounts of BiOCl plates coupled with g-C₃N₄ nanosheets. The effects of coupling the 2D structure of g-C₃N₄ with the 2D structure of BiOCl were systematically examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence (PL), lifetime decay measurement, surface charges of the samples at various pH conditions, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The prepared photocatalysts were used for the degradation of amine-based pharmaceuticals, and nizatidine was used as a model pollutant to evaluate the photocatalytic activity. The UV-vis DRS and other optical properties indicated the major effect of coupling of BiOCl with g-C₃N₄ into a 2D/2D structure. The results showed a narrowing in the band gap energy of the composite form, whereas the PL and lifetime analysis showed greater inhibition of the electron-hole recombination process and slightly longer charge carrier lifetime. Accordingly, the BiOCl/g-C₃N₄ composite samples exhibited an enhancement in the photocatalytic performance, specifically for the 10% BiOCl/g-C₃N₄ sample. Moreover, the zeta potential of this sample at different pH values was evaluated to determine the isoelectric point of the synthesized composite material. Consequently, the pH was adjusted to match the isoelectric point of the complex materials, which further enhanced the activity. Further degradation of pharmaceuticals was studied under solar light irradiation, and 96% degradation was achieved within 30 min.

Novel magnetically separable Fe3O4–WSe2/NG photocatalysts: synthesis and photocatalytic performance under visible-light irradiation

Visible light responsive Fe₃O₄–WSe₂/NG (nitrogen doped graphene oxide) heterojunction nanocomposites were synthesized by a hydrothermal synthesis route, in which Fe₃O₄ and WSe₂ particles were coated on the surface of NG.

g-C3N4/Bi4O5I2 2D–2D heterojunctional nanosheets with enhanced visible-light photocatalytic activity

The 2D–2D heterojunctional g-C₃N₄/Bi₄O₅I₂ nanosheets were successfully constructed based on band gap engineering design. It exhibits high visible-light-driven photocatalytic activity for degradation of RhB and NO removal.

A self-sacrifice template route to iodine modified BiOIO3: band gap engineering and highly boosted visible-light active photoreactivity

In this work we demonstrate the continuously adjustable band gap and visible-light photocatalysis activation of WBG BiOIO₃via iodine surface modification.

Facile fabrication of BiOIO3/BiOBr composites with enhanced visible light photocatalytic activity

BiOIO₃/BiOBr composite photocatalysts were successfully fabricated through a hydrothermal and subsequent chemical precipitation method.

Synchronously Achieving Plasmonic Bi Metal Deposition and I(-) Doping by Utilizing BiOIO3 as the Self-Sacrificing Template for High-Performance Multifunctional Applications

Herein, we uncover simultaneously achieving plasmonic Bi metal deposition and I(-) doping by employing wide-band-gap BiOIO3 as the self-sacrificing template. It was synthesized via a facile NaBH4-assisted in situ reduction route under ambient conditions. The reducing extent as well as photocatalytic levels can be easily modulated by controlling the concentration of NaBH4 solution. It is interesting that the band gap of BiOIO3 can be continuously narrowed by the modification, and the photoresponse range is drastically extended to cover the whole visible region. Bi/I(-) codecorated BiOIO3 not only exhibits profoundly upgraded photoreactivity in comparison with pristine BiOIO3 but also shows universally strong photooxidation properties toward decomposition of multiple industrial contaminants and pharmaceutical, including phenol, 2,4-Dichlorophenol (2,4-DCP), bisphenol A (BPA), dye model Rhodamine (RhB), tetracycline hydrochloride, and gaseous NO under visible light (λ ≥ 420 nm) or simulated solar light irradiation. It also outperforms the well-known and important photocatalysts C3N4, BiOBr, and Bi2WO6 for NO removal. The cooperative effects from Bi SPR and I(-) doping endow BiOIO3 with a narrowed band gap and highly boosted separation of charge carriers, thus responsible for the outstanding catalytic activity. The present study provides an absorbing candidate for practical environmental applications and also furthers our understanding of developing high-performance photocatalysts by manipulating manifold strategies in a facile way.

Synthesis and properties of visible light responsive g-C3N4/Bi2O2CO3 layered heterojunction nanocomposites

A g-C₃N₄/Bi₂O₂CO₃ layered heterojunction nanocomposite exhibits more effective separation of photogenerated electron–hole pairs and a stable chemical structure, thus showing higher photocatalytic activity and stability.

A thin empty-shell bismuth tungstate hierarchical structure constructed by the acid sculpture effect with improved visible-light photocatalytic activity

A thin empty-shell Bi₂WO₆hierarchical structure is constructed using a simple acid sculpture strategy, which shows excellent photocatalytic activity.

Coupling with a narrow-band-gap semiconductor for enhancement of visible-light photocatalytic activity: preparation of Bi2S3/g-C3N4 and application for degradation of RhB

Bi₂S₃ was synthesized on the surface of g-C₃N₄ to narrow the band gap of the catalyst for a visible-light response.

Template synthesis of carbon self-doped g-C3N4 with enhanced visible to near-infrared absorption and photocatalytic performance

Carbon self-doped g-C₃N₄ with enhanced visible to near-infrared absorption and photocatalytic activity was synthesized by a soft-template method.

A general method for type I and type II g-C3N4/g-C3N4 metal-free isotype heterostructures with enhanced visible light photocatalysis

Composite precursors were used to construct type I and type II g-C₃N₄/g-C₃N₄ metal-free isotype heterostructures based on different band-alignment patterns.