Turning trash to treasure: Innovative use of exhausted desiccant waste supported zinc indium sulphide for sustainable photocatalytic abatement of tetracycline

Employing an affordable and sustainable visible-light-driven system is crucial for organic pollutant abatement, in the field of photocatalysis. In the present investigation, a pioneering photocatalyst zinc indium sulphide, ZnIn2S4 (ZIS) supported on a silica gel matrix, SiO2 (SG) which is the leftover material after multiple rounds of dehumidification processes, was synthesized. The fabrication of the heterojunction facilitated enhancement in light absorption and charge separation efficiency. The photocatalytic performance was evaluated through the degradation of tetracycline (TC) under light irradiation. The nano-photocatalyst experienced detailed analysis using spectroscopic and microscopic methods. The ZIS/SG catalyst exhibited remarkable efficiency in degrading TC under visible light conditions, achieving a nearly 98-99% degradation. This performance surpassed the degradation rates of the original ZIS and SG catalysts by 3.6 and 4.45 times, respectively. Additionally, the catalyst was effectively used to control TC levels in real-time within pharmaceutical plant effluent, resulting in a degradation efficiency of 78.2%. With affordability, enhanced TC mineralization, and recyclability for up to six runs (efficiency ∼ 85%), the ZIS/SG photocatalyst exhibits desirable qualities of an ideal one. This innovative nano-photocatalyst introduces new possibilities for improving the process of photocatalytic decontamination of tenacious emerging pollutants by providing satisfactory reusability and stability.

Silica wastes derived multifunctional coatings for formaldehyde photodegradation and autonomous indoor humidity buffering

To maintain a comfortable and healthy indoor environment without large amounts of energy consumption is of great importance. The progress of multifunctional indoor coatings with formaldehyde photodegradation and humidity buffering capability is necessary. From the viewpoints of circular economy, the preparation of effective photocatalysts (denoted as sFCC/GCN-x and ESF/GCN-y) via the decoration of recycling industrial wastes (i.e., spent fluid catalytic cracking catalysts (sFCC) and enhancement silica fume (ESF)) onto graphitic carbon nitride (GCN) by using a simple route is reported. The obtained results show that the prepared sFCC/GCN-0.15 and ESF/GCN-0.15 photocatalysts have the rate constants of formaldehyde degradation of 0.0075 and 0.0082 min-1, respectively, which are superior to that of pristine GCN (0.0044 min-1) under visible-light irradiation. The enhanced transfer kinetics of photogenerated electrons and declined recombination of electron-hole pairs may account for the surpassing photocatalytic performance. Results obtained from electron paramagnetic resonance spectra and Mott-Schottky plots indicate that the formation of ･O2- via the reaction of O2 with electrons generated on the conduction band is the major reaction pathway to photodegrade formaldehyde under visible light. To further assess the real applications of prepared photocatalysts, the sFCC/GCN-0.15 and ESF/GCN-0.15 are used to fabricate the multifunctional coatings (denoted as s- and E-coatings) with sFCC and ESF as the main compositions. Experimentally, the E-coatings could reach the formaldehyde degradation efficiency of ca. 84.5% after 3 h of visible light irradiation and excellent humidity buffering ability (293.8 g m-2) which is at least 10-folds higher than commercial coatings (28.9 g m-2). This notable progress of humidity buffering capacity on E-coatings can be attributed to their surface textural properties. Most importantly, this study exemplifies the valorization of inorganic silica wastes to produce sustainable and multifunctional coatings which may offer the practical and cost-effective applications in the indoor living space.

Antimicrobial potential and rhodamine B dye degradation using graphitic carbon nitride and polyvinylpyrrolidone doped bismuth tungstate supported with in silico molecular docking studies

The environmental-friendly hydrothermal method has been carried out to synthesize Bi2WO6 and g-C3N4/PVP doped Bi2WO6 nanorods (NRs) by incorporating different concentrations of graphitic carbon nitride (g-C3N4) as well as a specified quantity of polyvinylpyrrolidone (PVP). Bi2WO6 doped with g-C3N4 provides structural and chemical stability, reduces charge carriers, degrades dyes, and, owing to lower bandgap energy, is effective for antibacterial, catalytic activity, and molecular docking analysis. The purpose of this research is the treatment of polluted water and to investigate the bactericidal behavior of a ternary system. The catalytic degradation was performed to remove the harmful rhodamine B (RhB) dye using NaBH4 in conjunction with prepared NRs. The specimen compound demonstrated antibacterial activity against Escherichia coli (E. coli) at both high and low concentrations. Higher doped specimens of g-C3N4/PVP-doped Bi2WO6 exhibited a significant improvement in efficient bactericidal potential against E. coli (4.55 mm inhibition zone). In silico experiments were carried out on enoyl-[acylcarrier-protein] reductase (FabI) and β-lactamase enzyme for E. coli to assess the potential of Bi2WO6, PVP doped Bi2WO6, and g-C3N4/PVP-doped Bi2WO6 NRs as their inhibitors and to justify their possible mechanism of action.

Visible light enhanced photocatalytic degradation of organic pollutants with SiO2/g-C3N4 nanocomposite for environmental applications

The development of eco-friendly photocatalysts is gaining attention as an effective approach for degrading organic pollutants. In the present study, the composite materials are composed of various components with varying structures that combine to enhance their characteristics and widen their applications. This work uses the hydrothermal method for the fabrication of a novel and steady SiO2/g-C3N4 photocatalyst. The amount of SiO2 was fixed, and graphitic carbon nitride (g-C3N4) was varied in the ratio (1:x, where x = 1, 2, 3) and abbreviated as SCN1, SCN2, and SCN3. The optical properties, surface morphology, and structural analysis of the prepared nanocomposites were studied using various techniques such as FTIR, TGA, X-ray diffraction, and ultraviolet-visible spectroscopy. The results show that SCN2 nanocomposites significantly improved the photocatalytic activity, with a degradation efficiency of 70% for auramine O and 84.6% for xylenol orange dye under visible light irradiation, which is a result of their large surface area and efficient electron-hole separation rate.

Solvothermal-based synthesis of barium stannate nanosheets coupled with copper manganate nanoparticles for efficient photooxidation of tetracycline under visible light

Photocatalytic oxidation of antibiotic waste over semiconducting heterojunction photocatalysts is considered eco-friendly because it is simple and operates under light irradiation. In this work, we apply a solvothermal-based process for obtaining high surface area barium stannate (BaSnO₃) nanosheets followed by adding 3.0-12.0 wt% of spinel copper manganate (CuMn₂O₄) nanoparticles to form n-n CuMn₂O₄/BaSnO₃ heterojunction photocatalyst after calcination process. The CuMn₂O₄-supported BaSnO₃ nanosheets exhibit mesostructure surfaces with a high surface area range of 133-150 m²g^-1. Moreover, introducing CuMn₂O₄ to BaSnO₃ shows a significant broadening in visible light absorption range due to bandgap reduction down to 2.78 eV in 9.0% CuMn₂O₄/BaSnO₃ compared to 3.0 eV for pure BaSnO₃. The produced CuMn₂O₄/BaSnO₃ is used for photooxidation of tetracycline (TC) in water as emerging antibiotic waste under visible light. The photooxidation of TC exhibits the first-order reaction model. The specific dose of 9.0 wt% CuMn₂O₄/BaSnO₃ at 2.4 gL^-1 displays the highest-performed and recyclable photocatalyst for total oxidation of TC after 90 min. This sustainable photoactivity is attributed to the improved light harvesting and charges migration upon coupling between CuMn₂O₄ and BaSnO₃.

In situ formation of red/black phosphorus-modified SiO2@g-C3N4 multi-heterojunction for the enhanced photocatalytic degradation of organic contaminants

A new heterojunction material BP/RP-g-C₃N₄/SiO₂ was obtained by a one-step ball milling method, and its photocatalytic capacity was researched by the degradation of Rhodamine B (RhB) and ofloxacin (OFL) in simulated sunlight. The construction of an in situ BP/RP heterojunction can achieve perfect interface contact between different semiconductors and effectively promote the separation of photogenerated carriers. The composite material was well characterized, which proved that the multi-heterogeneous structure was prepared. Furthermore, the type II heterojunction was formed between the g-C₃N₄ and BP/RP interface, playing an important role in the degradation and promoting electron transfer. The degradation effect of BP/RP-g-C₃N₄/SiO₂ on RhB reached 90% after 26 min of simulated solar irradiation, which was 1.8 times that of g-C₃N₄/SiO₂. The degradation of OFL by BP/RP-g-C₃N₄/SiO₂ reached 85.3% after illumination for 50 min, while the degradation of g-C₃N₄/SiO₂ was only 35.4%. The mechanisms were further discussed, and ˙O₂ ^- and h⁺ were found to be the main active substances to degrade RhB. The catalyst also revealed distinguished stability of catalyst and recyclability, and the degradation effect of RhB can still realize 85% after 4 runs of experiment. Thus, this study provided a novel method for the design and preparation of multi-heterojunction catalysts in the removal of organic pollutants from wastewater.

SiC Foams for the Photocatalytic Degradation of Methylene Blue under Visible Light Irradiation

SiC foams were synthesized by impregnating preceramic polymer into polyurethane foam templates, resulting in a photo-catalytically active material for the degradation of methylene blue. The crystalline structure, electronic properties, and photocatalytic performance of the SiC foams were characterized using a series of experimental techniques, including X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy, N2 physisorption measurements, UV-visible spectroscopy, and methylene blue photodegradation tests. The original polyurethane template's microporous structure was maintained during the formation of the SiC foam, while additional mesopores were introduced by the porogen moieties added to the preceramic polymers. The prepared SiC-based photocatalyst showed attractive photocatalytic activity under visible light irradiation. This structured and reactive material offers good potential for application as a catalytic contactor or membrane reactor for the semi-continuous treatment of contaminated waste waters in ambient conditions.

Supported nanostructured photocatalysts: the role of support-photocatalyst interactions

Heterogeneous photocatalysis employing semiconductor oxide photocatalysts is a sustainable and promising method for environmental remediation and clean energy generation. In this context, nanostructured photocatalysts, with at least one dimension in the 1‒100 nm size regime, have attracted ever-growing attention due to their unique and often enhanced size-dependent physicochemical properties. While their reduced size ensures enhanced photocatalytic performance, the same makes it difficult and time/energy-demanding to remove/recover such nanostructured photocatalysts from aqueous media. This fundamental limitation has paved the way towards developing supported nanophotocatalysts where the active photocatalytic nanostructures are coated on the surface of polymeric or inorganic support materials, often in a core@shell conformation. This arrangement solves the problem of photocatalysts' recovery for effective reuse or recycling and leads to improved and desired target properties due to specific photocatalyst-support interactions. While the enhanced physicochemical properties of supported photocatalysts have been widely studied in many target applications, the role of support-photocatalysts interactions in improving these properties remains unexplored. This review article provides an updated viewpoint on the photocatalyst-support interactions and the resulting unique physiochemical properties important for diverse photochemical applications and the design of practical devices. While exploring the properties of supported nanostructured metal oxide/sulfides photocatalysts such as TiO₂ and MoS₂, we also briefly discuss the common strategies employed to coat the active nanomaterials on the surface of different supports (organic/polymeric, inorganic, active, inert, and magnetic).

Porous graphitic carbon nitride with high concentration of oxygen promotes photocatalytic H2 evolution

Porous structure design and the content regulation of heteroelements have been proved to be effective strategies to boost photocatalytic H₂ generation activity of graphitic carbon nitride (g-C₃N₄) based photocatalyst. Herein, a series of porous graphitic carbon nitride with high concentration of oxygen (g-C₃N₄-O) photocatalysts were synthesized via in situ polymerization process using colloidal SiO₂ as oxygen source. The content of oxygen within the g-C₃N₄-O photocatalysts could be tuned by adjusting the amount of added colloidal SiO₂ during the preparation procedure. The introduced oxygen replaced two-coordinated nitrogen atom, influencing band edge position and localized electron distribution, thereby enhancing visible light harvesting and photoelectric conversion. As a result, the g-C₃N₄-O photocatalyst with an optimal oxygen content (8.39 wt%) showed 10.5 fold enhancement in H₂ evolution rate compared to that of bulk g-C₃N₄, attributed to the porous structure and high concentration of incorporated oxygen.

Supramolecular Precursor Strategy to Construct g-C3N4/Silica Hybrid Nanosheets for Photocatalytic Degradation of Dye and Antibiotic Pollutants

To construct a highly active g-C₃N₄ (CN)/silica hybrid nanosystem, the supramolecular precursor strategy of introducing melamine-cyanuric acid (MCA) by synergistically using micromolecular melamine (m) and urea (u) for CN nanostructure construction on the silica nanosheets (SiNSs) surface was researched. The results showed that the introduction of MCA supramolecular aggregates promoted the generation of ordered CN nanostructures attached to SiNSs, and the morphology of the CN nanostructure could be regulated through the m/u mass ratio. When the ratio is equal to 1/30, a typical g-C₃N₄/silica hybrid nanosheet (mu-CN/SiNSs-3) was successfully prepared, which showed the ultra-high photocatalytic activity for Rhodamine B dye degradation within 25 min with an apparent rate constant of 0.186 min^-1, owing to the large surface area of highly dispersed and ordered CN nanosheets, a strong interaction between CN and SiNSs, high photogenerated carriers separation efficiency, and the more negative conduction band potential offering more active species of ¹O₂ and ^•O₂^-. Unexpectedly, the mu-CN/SiNSs-2 composite (m/u = 1/10) exhibited the highest activity for tetracycline antibiotic degradation, mainly due to the morphological advantage of a certain number of nanotubes generated on the CN/SiNSs hybrid nanosheets. It indicates that the supramolecular precursor strategy by synergistically using melamine and urea is highly efficient for the nanostructure construction of the CN/SiNSs hybrid system, enabling an appropriate nanostructure for the photodegradation of various pollutants.

A readily synthesized bismuth oxyiodide/attapulgite for the photodegradation of tetracycline under visible light irradiation

Bismuth oxyiodide and attapulgite have proven to be potential materials for the removal of emerging contaminants in wastewater.

A Review: Photocatalysts Based on BiOCl and g-C3N4 for Water Purification

Many organic pollutants are discharged into the environment, which results in the frequent detection of organic pollutants in surface water and underground water. Some of the organic pollutants can stay for a long time in the environment due to their recalcitrance. Advanced oxidation processes (AOPs) can effectively treat the recalcitrant organic compounds in water. Photocatalysis as one of the AOPs has attracted a lot of interest. BiOCl and g-C3N4 are nice photocatalysts. However, their catalytic activity should be further improved for industrial utilization. The construction of heterojunction between the two different components is deemed as an efficient strategy for developing a highly efficient photocatalyst. As a typical type-II heterojunction, g-C3N4/BiOCl heterojunctions showed better photocatalytic performance. To date, the g-C3N4/BiOCl composites were mainly studied in the field of water purification. The photoactivity of the pristine catalysts was greatly enhanced by the combination of the two materials. However, three kinds of proposed mechanisms were used to explain the improvement of the g-C3N4/BiOCl heterojunctions. But few researchers tried to explain why there were three different scenarios employed to explain the charge transfer. According to the articles reviewed, no direct evidence could indicate whether the band structures of the heterojunctions based on BiOCl and g-C3N4 were changed. Therefore, many more studies are needed to reveal the truth. Having a clearer understanding of the mechanism is beneficial for researchers to construct more efficient photocatalysts. This article is trying to start a new direction of research to inspire more researchers to prepare highly effective photocatalysts.

Unmasking the Role of an Amorphous/Amorphous Interface and a Crystalline/Amorphous Interface in the Transition of Charge Carriers on the CN/SiO2/WO3 Photocatalyst

Making heterojunctions between semiamorphous carbon nitride (CN) and other well-matched semiconductors (or even insulators) can solve many photocatalytic problems such as the recombination of charge carriers. However, many researchers encounter intrinsic problems including the lack of detailed information on contact boundaries in their heterojunctions, particularly in the amorphous/amorphous interface. In addition, the roles of contact boundaries in the photocatalytic mechanisms of many heterojunctions are still obscure. This study synthesized a novel CN/SiO₂/WO₃ photocatalyst having two different contact features by constructing an amorphous/amorphous (CN/SiO₂) interface and a crystalline/amorphous (WO₃/CN) interface to provide deep insights into heterojunction interfaces. SiO₂ plays an exceptional role as a major component in the separation and migration of charge carriers. It not only modifies the texture but also transfers electrons. Surprisingly, the amorphous/amorphous interface shows an unpredicted capability for decreasing the recombination of electron-hole pairs. Based on capturing experiments and photoluminescence investigations, the amorphous/amorphous interface is unprecedently present in the production of hydroxyl radicals, while the crystalline/amorphous interface gives more superoxide radicals. This work provides a platform that opens a new perspective on the selection of mutual photocatalysts. It extends boundaries of conventional heterojunctions.

Unique hierarchical SiO2@ZnIn2S4 marigold flower like nanoheterostructure for solar hydrogen production

The novel marigold flower like SiO2@ZnIn2S4 nano-heterostructure was fabricated using an in situ hydrothermal method. The nanoheterostructure exhibits hexagonal structure with marigold flower like morphology. The porous marigold flower assembly was constructed using ultrathin nanosheets. Interestingly, the thickness of the nanopetal was observed to be 5-10 nm and tiny SiO2 nanoparticles (5-7 nm) are decorated on the surface of the nanopetals. As the concentration of SiO2 increases the deposition of SiO2 nanoparticles on ZnIn2S4 nanopetals increases in the form of clusters. The optical study revealed that the band gap lies in the visible range of the solar spectrum. Using X-ray photoelectron spectroscopy (XPS), the chemical structure and valence states of the as-synthesized SiO2@ZnIn2S4 nano-heterostructure were confirmed. The photocatalytic activities of the hierarchical SiO2@ZnIn2S4 nano-heterostructure for hydrogen evolution from H2S under natural sunlight have been investigated with regard to the band structure in the visible region. The 0.75% SiO2@ZnIn2S4 showed a higher photocatalytic activity (6730 μmol-1 h-1 g-1) for hydrogen production which is almost double that of pristine ZnIn2S4. Similarly, the hydrogen production from water splitting was observed to be 730 μmol-1 h-1 g-1. The enhanced photocatalytic activity is attributed to the inhibition of charge carrier separation owing to the hierarchical morphology, heterojunction and crystallinity of the SiO2@ZnIn2S4.

Efficient activation of peroxymonosulfate by composites containing iron mining waste and graphitic carbon nitride for the degradation of acetaminophen

In this work, the potential to use an iron mining waste (IW), rich in α-Fe₂O₃ and α-FeOOH, for the development of composites based on graphitic carbon nitride (CN) is demonstrated. These materials were synthesized through a simple thermal treatment at 550 °C of a mixture containing melamine and different IW mass percentages, giving rise to the catalysts xIWCN (where x is related to the initial mass percentage of IW). The iron phases of the precursor were partially transformed throughout the formation of the composites, in such a way that a mixture of α-Fe₂O₃ and γ-Fe₂O₃ was observed in their final composition. Furthermore, structural defects were produced in the carbonaceous matrix of the materials, causing the fragmentation of g-C₃N₄ and an increase of surface area. The catalytic activities of these composites were evaluated in reactions of peroxymonosulfate activation for the degradation of paracetamol. Among these materials, the composite 20IWCN showed the best catalytic activity, being able to degrade almost 90 % of the total paracetamol in only 20 min of reaction. This catalyst also demonstrated high chemical stability, being successfully utilized in five consecutive reaction cycles, with negligible iron leaching.

A radially controlled ZnS interlayer on ultra-long ZnO-Gd2S3 core-shell nanorod arrays for promoting the visible photocatalytic degradation of antibiotics

Nanorod (NR) arrays offer commendable visible-light-driven photocatalytic performances. Herein, we describe the construction of a ternary ZnO-ZnS-Gd₂S₃ nanostructural array in which a sulfidation process is used to decorate a Gd₂S₃ shell layer with a ZnS interface over vapor-phase-grown vertically-aligned ZnO. With control over the shell-wall thickness, the shell layer of ∼25 nm wall thickness on the ultra-long ZnO NR arrays exhibited a higher catalytic efficiency close to 3.3, 2.0, 1.2, and 1.8 times those of the bare ZnO, the ZnO-ZnS, the Gd₂S₃-decorated (∼10 nm) and Gd₂S₃ shell-layered (∼40 nm) ZnO-ZnS core-shell structures, respectively. The core-shell geometry and the shell-wall thickness with maximized contact interface afforded increased light absorption in the visible region and effectively retarded the recombination rate of the photoinduced charge carriers by confining electrons and holes separately, thus providing advantages in terms of the degradation of the pharmaceutical residue tetracycline and the industrial pollutant 4-nitrophenol in wastewater.

Study on Visible Light Catalysis of Graphite Carbon Nitride-Silica Composite Material and Its Surface Treatment of Cement

Cement-based composite is one of the essential building materials that has been widely used in infrastructure and facilities. During the service of cement-based materials, the performance of cement-based materials will be affected after the cement surface is exposed to pollutants. Not only can the surface of cement treated with a photocatalyst degrade pollutants, but it can also protect the cement-based materials from being destroyed. In this study, graphite carbon nitride-silica composite materials were synthesized by thermal polymerization using nanosilica and urea as raw materials. The effect of nanosilica content and specific surface area were investigated with the optimal condition attained to be 0.15 g and 300 m2/g, respectively. An X-ray diffractometer, thermogravimetric analyzer, scanning electron microscope, a Brunauer–Emmett–Teller (BET) specific surface area analyzer and ultraviolet-visible spectrophotometer were utilized for the characterization of as-prepared graphite carbon nitride-silica composite materials. Subsequently, the surface of cement-based materials was treated with graphite carbon nitride-silica composite materials by the one-sided immersion and brushing methods for the study of photocatalytic performance. By comparing the degradation effect of Rhodamine B, it was found that the painting method is more suitable for the surface treatment of cement. In addition, through the reaction of calcium hydroxide and graphite carbon nitride-silica composite materials, it was found that the combination of graphite carbon nitride-silica composite materials and cement is through C-S-H gel.

Bio-inspired SiO2-hard-template reconstructed g-C3N4 nanosheets for enhanced photocatalytic hydrogen evolution

Building architectures to manipulate light propagation using a light-conversion matrix is one of the most competitive strategies to enhance photocatalytic performance.

Surface defect-abundant one-dimensional graphitic carbon nitride nanorods boost photocatalytic nitrogen fixation

Defective g-C₃N₄ nanorods enable to boots the adsorption and cleavage of N₂ molecules to achieve higher photocatalytic nitrogen fixation performance.

Study on the photoelectrocatalytic performance of a WO3thin film electrode by constructing a BiOI/WO3heterojunction

A WO₃thin film electrode containing a BiOI/WO₃heterojunction was constructed using simple hydrothermal and electrodeposition methods. This study provides a novel theoretical basis for the development of high performance WO₃photocatalytic materials.

Z-scheme inverse opal CN/BiOBr photocatalysts for highly efficient degradation of antibiotics

Optimizing the heterojunction structure of semiconductor photocatalysts is vital for utilizing their abilities in organic matter degradation.

Large enhanced photocatalytic activity of g-C3N4 by fabrication of a nanocomposite with introducing upconversion nanocrystal and Ag nanoparticles

A novel heterostructured nanocomposite UCNPs@SiO2@Ag/g-C3N4 was developed for the first time to substantially boost the solar-light driven photocatalytic activity of g-C3N4. Its photocatalytic properties and photocatalytic mechanism were investigated. The as-synthesized photocatalyst with excellent improvement in the solar absorption and separation efficiency of photoinduced electron-hole pairs exhibited optimum solar-induced photocatalytic activity in dye degradation and hydrogen production. The experimental results showed that the rates of degradation of Rhodamine B (RhB) and hydrogen evolution were about 10 and 12 times higher than that of pristine g-C3N4, respectively. The excellent photocatalytic activity was attributed to the synergetic effect of upconversion nanoparticles (UCNPs) and Ag nanoparticles (NPs) on the modification of the photocatalytic properties of g-C3N4, resulting in a broad light response range for g-C3N4 as well as the fast separation and slow recombination of photoinduced electron-hole pairs. This study provides new insight into the fabrication of g-C3N4-based nanocomposite photocatalysts with high catalytic efficiency through the artful assembly of UCNPs, Ag NPs and g-C3N4 into a hetero-composite nanostructure. The prominent improvement in photocatalytic activity enables the potential application of g-C3N4 in the photocatalytic degradation of organic pollutants and hydrogen production utilizing solar energy.

Impact of Average, Local, and Electronic Structure on Visible Light Photocatalysis in Novel BiREWO6 (RE = Eu and Tb) Nanomaterials

Crystal structures of hydrothermally synthesized BiEuWO₆ and BiTbWO₆ nanomaterials are deduced for the first time by combined Rietveld refinement of neutron and synchrotron data using the ordered and disordered models available in literature. The ordered model is validated for the average structure of these nanomaterials, and it is further supported by the local structure analysis using neutron pair distribution function. Nanomaterials are characterized by field-emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller surface area, diffused reflectance spectroscopy, and Raman Spectroscopy. Rare-earth-substituted nanomaterials are found to be efficient photocatalysts over the parent Bi₂WO₆ under visible light irradiation for Congo-red dye degradation. Particularly, BiTbWO₆ shows an enhanced photocatalytic (PC) activity compared to BiEuWO₆, as evidenced from the photoelectrochemical and time-resolved fluorescence studies. The difference in the observed PC activity of these nanomaterials is also explored through a detailed comparison of crystal structure and electronic structure calculated through the density functional theory method.

Facile synthesis of graphitic C3N4 nanoporous-tube with high enhancement of visible-light photocatalytic activity

A simple and convenient method was used to synthesize a graphitic carbon nitride (g-C₃N₄) nanoporous-tube by using SiO₂ nanoparticles as pore formers. The structure of the g-C₃N₄ nanoporous-tube was characterized by the SEM and TEM images. Taking photodegradation of RhB as an example, the photocatalytic activity of the as-prepared g-C₃N₄ nanoporous-tube was investigated. It can photodegrade 90% RhB in 40 min under visible-light irradiation and obtain a k value of 0.04491 min^-1, which is 8.16 times that of bulk g-C₃N₄, 3.09 times that of tubular g-C₃N₄ and 1.48 times that of tubular g-C₃N₄-SiO₂. The significant enhancement in photocatalytic efficiency is due to the edge effect of the pores and the special structure of the tubes. In addition, the possible mechanism of photocatalytic degradation of RhB was also proposed based on the trapping experiment of active species, which indicated that the superoxide radicals ([Formula: see text]) and the holes (h ⁺) were the main reactive species in this photocatalyst. This work may open up a new idea of innovation in g-C₃N₄ structure and inspire its follow-up study.

Synthesis of mesoporous SiO2/Cu2O–graphene nanocomposites and their highly efficient photocatalytic performance for dye pollutants

A mesoporous SiO₂/Cu₂O–graphene composite, a novel material, was successfully synthesized using a self-assembly method with tetraethyl orthosilicate (TEOS).