Properties, optimized morphologies, and advanced strategies for photocatalytic applications of WO3 based photocatalysts

Prohibiting the electron-phonon coupling effect in tungsten trioxide nanosheet colloid with enhanced photocatalytic antibacterial capacity

The serious combination of abundant electrons/holes in bulk primarily hinders the efficiency in the photocatalytic reaction. It is crucial to control the spatial charge dynamics through delicately designing the crystal configuration of photocatalyst. In this work, a modified tungsten trioxide nanosheet colloid (M-WO3) was synthesized by an ion exchange method. Compared to pristine WO3 (P-WO3), the crystal lattice vibration frequency of M-WO3 increases from 2.8 meV to 4.3 meV, which effectively prohibits electron-phonon coupling and powerfully accelerates the separation and transfer of photoinduced charge carriers. Irradiated by visible-light, M-WO3 shows much higher photocatalytic bacterial inactivation performance than P-WO3. In addition, this regulation method increases the surface charges of the WO3 colloid to improve its stability, which endows this colloid photocatalyst with broad prospects in practical photocatalytic antibacterial applications. This work offers guidance to construct efficiently separated photoinduced electron/hole pairs of the colloid photocatalyst by designing its crystal structure.

Anelosimuseximius bioinspired ZnO nano cobwebs for environmental remediation of drugs and endocrine disruptors from water

The pollution of wastewater with pharmaceuticals and endocrine-disrupting chemicals (EDCs) in populated areas poses a growing threat to humans and ecosystems. To address this serious problem, various one-dimensional (1D) hierarchical ZnO-based nanostructures inspired by Anelosimus eximius cobwebs were developed and successfully grown on a glass substrate through simple hydrothermal synthesis. The nanorods (nr) obtained during primary growth were chemically etched with KOH (ZnOnr-KOH), followed by the secondary growth of nano cobweb-like (ncw) structures using polyethyleneimine (ZnOnr/ncw). These structures were further decorated by the photoreduction of Ag nanoparticles (ZnOnr/ncw/Ag). The feasibility of ZnO-based 1D nanostructures to remove pollutants was demonstrated by degrading commonly prescribed pharmaceutical drugs (diclofenac and carbamazepine) in a miniature cuvette reactor. The photocatalytic activities for drug degradation generally decreased in the order ZnOnr/ncw/Ag > ZnOnr/ncw > ZnOnr-KOH. Additionally, the suitability of the samples for scaling up and practical application was demonstrated by photocatalytic degradation of the hormone estriol (E3) in a flow-through photoreactor. The photocatalytic degradation efficiency of E3 followed the same trend observed for drug degradation, with the complete elimination of the endocrine disruptor achieved by the best-performing ZnOnr/ncw/Ag within 4 h, due to optimized charge transfer and separation at the heterostructure interface.

Visible light-induced photocatalytic degradation of tetrabromobisphenol A on platinized tungsten oxide

In this study, we investigated the degradation of the flame retardant tetrabromobisphenol A (TBBPA) using platinized tungsten oxide (Pt/WO3), synthesized via a simple photodeposition method, under visible light. The results of degradation experiments show a significant enhancement in TBBPA degradation upon surface platinization of WO3, with the degradation rate increasing by 13.4 times compared to bare WO3. The presence of Pt on the WO3 surface stores conduction band electrons, which facilitates the two-electron reduction of oxygen and enhances the production of valence band holes (hVB+) and hydroxyl radicals (●OH). Both hVB+ and ●OH are significantly involved in the degradation of TBBPA in the visible light-irradiated Pt/WO3 system. This was verified through fluorescence spectroscopy employing coumarin as a chemical probe and oxidizing species-quenching experiments. The analysis of degradation products and their toxicity assessment demonstrate that the toxicity of TBBPA-contaminated water is significantly reduced after Pt/WO3 photocatalysis. The degradation rate of TBBPA increased with increasing Pt/WO3 dosage, reached an optimum at a Pt content of 0.5 wt%, but decreased with increasing TBBPA concentration. The decrease in degradation efficiency of Pt/WO3 was minor, both in the presence of various anions and after repeated use. This study proposes that Pt/WO3 is a viable photocatalyst for the degradation of TBBPA in water under visible light.

Reduction-Assisted Calcination Enhances the Photocatalytic Activity of ZnO and WO3 Nanoparticles in Biomass Conversion

Rising energy needs and environmental issues have prompted the creation of effective and affordable photocatalysts for converting biomass. Utilizing abundant biomass, oxidation of 5-hydroxymethylfurfural (HMF) emerges as a method for generating high-value chemicals from biomass, offering an alternative to fossil fuels. We synthesized defect-engineered metal oxides (ZnO and WO3) by calcination with NaBH4 as a reducing agent. Atomic-level analyses identified oxygen vacancy defects induced by the reduction of metal ions within the metal oxide nanoparticles. Further analysis showed an unchanged band gap but an up to 4-fold increase in current density. This enhancement is attributed to the trapping of electrons in defect sites created during the calcination process. The formation of new electron donor states hindered photogenerated electron-hole recombination, enhancing the photocatalytic efficiency of the metal oxide. The photocatalytic degradation yield of HMF was over 95%, and the selective organic products 2,5-diformylfuran (DFF) and 2,5-furandicarboxylic acid (FDCA) were obtained without byproducts. Kinetic studies demonstrated that the photocatalytic conversion reaction rates were accelerated by up to 3.5-fold. Improved photocatalytic activity for HMF oxidation was achieved by introducing oxygen vacancy defects upon the reduction of metal ions within the metal oxides. Our results provide a promising approach for designing efficient photocatalysts.

Synthesis and Characterization of Composite WO3 Fibers/g-C3N4 Photocatalysts for the Removal of the Insecticide Clothianidin in Aquatic Media

Photocatalysis is a prominent alternative wastewater treatment technique that has the potential to completely degrade pesticides as well as other persistent organic pollutants, leading to detoxification of wastewater and thus paving the way for its efficient reuse. In addition to the more conventional photocatalysts (e.g., TiO2, ZnO, etc.) that utilize only UV light for activation, the interest of the scientific community has recently focused on the development and application of visible light-activated photocatalysts like g-C3N4. However, some disadvantages of g-C3N4, such as the high recombination rate of photogenerated charges, limit its utility. In this light, the present study focuses on the synthesis of WO3 fibers/g-C3N4 Z-scheme heterojunctions to improve the efficiency of g-C3N4 towards the photocatalytic removal of the widely used insecticide clothianidin. The effect of two different g-C3N4 precursors (urea and thiourea) and of WO3 fiber content on the properties of the synthesized composite materials was also investigated. All aforementioned materials were characterized by a number of techniques (XRD, SEM-EDS, ATR-FTIR, Raman spectroscopy, DRS, etc.). According to the results, mixing 6.5% W/W WO3 fibers with either urea or thiourea derived g-C3N4 significantly increased the photocatalytic activity of the resulting composites compared to the precursor materials. In order to further elucidate the effect of the most efficient composite photocatalyst in the degradation of clothianidin, the generated transformation products were tentatively identified through UHPLC tandem high-resolution mass spectroscopy. Finally, the detoxification effect of the most efficient process was also assessed by combining the results of an in-vitro methodology and the predictions of two in-silico tools.

WO3-x nanorods/rGO/AgBiS2 Z-scheme heterojunction with comprehensive spectrum response and enhanced Fenton and photocatalytic activities

Tetracycline (TC) antibiotics and dyes are the prevalent water contaminants, and their removal from the water through photocatalysis is a plausible approach. However, most semiconductors in their pristine form need to be improved to be exploited in photocatalysis owing to poor photoresponse, intense carrier recombination, and inertness without irradiation. Herein, we demonstrate the modification of defective WO3-x by rGO and AgBiS2 in the form of WO3-x/rGO/AgBiS2 (R2). It exploits the superior conductivity and synergism of rGO to inhibit carrier recombination; thereby, Z-scheme heterojunction with AgBiS2 provides high redox potential. Defects in WO3-x enable electron (e-) storage in R2, which decomposes H2O2 to generate ROS without irradiation. Owing to these essences and broad-spectrum response, it removed 93.72, 82.77, and 84.82% of TC during photo-Fenton (PFR), night-Fenton (NFR), and photocatalytic (PCR) reactions, respectively. Its removal rates reached 94.74, 81.54, and 87.50% against rhodamine B (RhB) during PFR, NFR, and PCR, respectively. It is superior to memory catalysis (MC) and conventional Fenton reactions (CFR) because it can perform without and with irradiation across a broader pH range. So, this work is conducive to designing WO3-x-based catalysts to combat environmental and energy crises.

A novel nanocomposite for photocatalytic rhodamine B dye removal from wastewater using visible light

Providing safe access to water and addressing the impact of waterborne diseases, which claim over two million lives annually, is a major contribution to water purification. The study introduces a novel nanocomposite, Ch/Fe3O4/α-MoO3, which exhibits outstanding photocatalytic efficacy under visible light. An in-depth investigation of the nanocomposite's synthesis, characterization, and photodegradation mechanisms reveals its outstanding capabilities. Photocatalytic activity is influenced by the catalytic dose, pH, dye concentration, and reaction time, according to the study. A response surface method is used to determine the optimal conditions for Rhodamine B degradation, which results in 96.3% removal efficiency at pH 8.5, dye concentration 25 mg/L, nanocomposite dose at 22 mg/L, and reaction time 50 min. As a result of its high surface area, biocompatibility, availability, and magnetization with iron compounds, Chitosan is an excellent substrate for enhancing the photocatalytic properties of MoO3 nanoparticles. A nanocomposite with an energy band of 3.18 eV exhibits improved visible light absorption. This study confirms the nanocomposite's recyclability and stability, affirming its practicality. Besides dye removal, it offers hope for the global quest for clean water sources by addressing a broader range of waterborne contaminants. By combining molybdenum and magnetite, nanocomposite materials facilitate the degradation of pollutant and bacteria, contributing positively to society's quest for clean and safe water. It emphasizes the role nanotechnology plays in preserving human health and well-being in combating waterborne diseases.

Enhanced photocatalytic ammonia oxidation over WO3@TiO2 heterostructures by constructing an interfacial electric field

WO3 nanorods and xWO3@TiO2 (WO3/TiO2 mass ratio (x) = 1-5) photocatalysts were synthesized using the hydrothermal and sol-gel methods, respectively. The photocatalytic activities of xWO3@TiO2 for NH3 oxidation first increased and then decreased with a rise in TiO2 content. Among them, the heterostructured 3WO3@TiO2 photocatalyst showed the highest NH3 conversion (58 %) under the simulated sunlight irradiation, which was about two times higher than those of WO3 and TiO2. Furthermore, the smallest amounts of by-products (i.e., NO and NO2) were produced over 3WO3@TiO2. The enhancement in photocatalytic performance (i.e., NH3 conversion and N2 selectivity) of 3WO3@TiO2 was mainly attributed to the formed interfacial electric field between WO3 and TiO2, which promoted efficient separation and transfer of photogenerated charge carriers. Based on the results of reactive species trapping and active radical detection, photocatalytic oxidation of NH3 over 3WO3@TiO2 was governed by the photogenerated holes and superoxide radicals. This work combines two strategies of morphological regulation and interfacial electric field construction to simultaneously improve light utilization and photogenerated charge separation efficiency, which promotes the development of full-spectrum photocatalysts for the removal of ammonia.

Photocatalytic degradation of tetracycline using a novel WO3-ZnO/AC under visible light irradiation: Optimization of effective factors by RSM-CCD

Mitigating pharmaceutical pollution in the global environment is imperative, and tetracycline (TC) is a commonly utilized antibiotic in human and veterinary medicine. The persistent existence of TC highlights the necessity of establishing efficient measures to protect water systems and the environment from detrimental contaminants. Herein, a novel rhubarb seed waste-derived activated carbon-supported photocatalyst (WO3-ZnO/RUAC) was synthesized by combining wet impregnation and ultrasonic methods. The activated carbon (AC) was obtained from rhubarb seed waste for the first time via chemical activation. The function of AC as an electron acceptor and in separating electron-hole pairs was illuminated by characterization analyses that included XRD, FTIR, XPS, SEM, TEM, PL, EIS, TPC, and UV-DRS. Using the response surface methodology-central composite design (RSM-CCD) technique, the synthesis parameters of the composite were systematically optimized. Under ideal conditions, with a TC concentration of 33 mg. L-1, pH of 4.57, irradiation time of 108 min, and catalyst dose of 0.85 g. L-1, the highest degradation efficiency of TC by this composite, achieved 96.5%, and it was reusable for five cycles. Subsequently, trapping tests and electron spin resonance (ESR) analysis were conducted, elucidating that •OH and •O2- radicals played pivotal roles in the photocatalytic degradation of TC. This research offers valuable insights into utilizing the AC-based photocatalyst to degrade pharmaceutical micropollutants effectively.

Organic Donor-Acceptor Systems for Photocatalysis

Organic semiconductor materials are considered to be promising photocatalysts due to their excellent light absorption by chromophores, easy molecular structure tuning, and solution-processable properties. In particular, donor-acceptor (D-A) type organic photocatalytic materials synthesized by introducing D and A units intra- or intermolecularly, have made great progress in photocatalytic studies. More and more studies have demonstrated that the D-A type organic photocatalytic materials combine effective carrier separation, tunable bandgap, and sensitive optoelectronic response, and are considered to be an effective strategy for enhancing light absorption, improving exciton dissociation, and optimizing carrier transport. This review provides a thorough overview of D-A strategies aimed at optimizing the photocatalytic performance of organic semiconductors. Initially, essential methods for modifying organic photocatalytic materials, such as interface engineering, crystal engineering, and interaction modulation, are briefly discussed. Subsequently, the review delves into various organic photocatalytic materials based on intramolecular and intermolecular D-A interactions, encompassing small molecules, conjugated polymers, crystalline polymers, supramolecules, and organic heterojunctions. Meanwhile, the energy band structures, exciton dynamics, and redox-active sites of D-A type organic photocatalytic materials under different bonding modes are discussed. Finally, the review highlights the advanced applications of organic photocatalystsand outlines prospective challenges and opportunities.

Cu2O/WO3 S-scheme heterojunctions for photocatalytic degradation of levofloxacin based on coordination activation

Heterogeneous photocatalytic degradation of antibiotic involves the activation of antibiotic molecules and the photocatalytic oxidation process. However, the simultaneous improvement of these processes is still a challenge. Herein, S-scheme heterojunctions consisted of Cu2O nanocluster with defective WO3 nanosheets were constructed for efficient photocatalytic degradation of levofloxacin (LVX). The typical CNS-5 composite (5 wt% Cu2O/WO3) achieves an optimal LVX degradation efficiency of 97.9% within 80 min. The spatial charge separation and enhancement of redox capacity were realized by the formation of S-scheme heterojunction between Cu2O and WO3. Moreover, their interfacial interaction would lead to the loss of lattice oxygen and the generation of W5+ sites. It is witnessed that the C-N of piperazine ring and CO of carboxylic acid in LVX are coordinated with W5+ sites to build the electronic bridge to activate LVX, greatly promoting the further degradation. This work highlights the important role of selective coordination activation cooperated with S-type heterojunctions for the photocatalytic degradation and offers a new view to understand the degradation of antibiotics at molecular level.

Highly efficient ZnO/WO3 nanocomposites towards photocatalytic gold recovery from industrial cyanide-based gold plating wastewater

Discharging the gold-contained wastewater is an economic loss. In this work, a set of ZnO/WO3 was facile synthesized by hydrothermal method in order to recover gold from the industrial cyanide-based gold plating wastewater by photocatalytic process. Effect of ZnO contents coupled with WO3 was first explored. Then, effects of operating condition including initial pH of wastewater, type of hole scavenger, concentration of the best hole scavenger and photocatalyst dose were explored. A series of experimental results demonstrated that the ZnO/WO3 nanocomposite with 5 wt% ZnO (Z5.0/WO3) depicted the highest photocatalytic activity for gold recovery due to the synergetic effect of oxygen vacancies, a well-constructed ZnO/WO3 heterostructure and an appropriate band position alignment with respect to the redox potentials of [Au(CN)2]- and hole scavengers. Via this ZnO/WO3 nanocomposite, approximately 99.5% of gold ions was recovered within 5 h using light intensity of 3.57 mW/cm2, catalyst dose of 2.0 g/L, ethanol concentration of 20 vol% and initial pH of wastewater of 11.2. In addition, high stability and reusability were observed with the best nanocomposite even at the 5th reuse. This work provides the guidance and pave the way for designing the ZnO/WO3 nanocomposite for precious metal recovery from a real industrial wastewater.

Carbonized polymer dots modified ZnIn2S4 microspheres for visible-light-driven hydrogen evolution promotion performance

To effectively separate electron-hole pairs produced by light, a heterojunction arrangement can be employed, thereby improving photocatalytic efficiency. In this study, a simple hydrothermal process is used to manufacture carbonized polymer dots/ZnIn2S4 (CPDs/ZIS) heterostructure, which enhances the light absorption and charge carrier lifetime in comparison to bare ZnIn2S4 (ZIS). Upon irradiation with visible light, the 3-CPDs/ZIS composite generates hydrogen at a rate of 133 μmol g-1 h-1, which is 8.9 times faster than that of pure ZIS. The addition of CPDs can increase the range of light that can be absorbed, extend the service life of the optical charge, increase the specific surface area, and promote charge separation and transmission, which could effectively accelerate the photocatalytic reduction reaction. The presence of CPDs results in the introduction of multiple transition energy states and a decrease in the H* adsorption free energy, which enhances the hydrogen evolution activity according to the theoretical calculation findings of density functional theory (DFT) and Gibbs free energy of the hydrogen evolution process. Combining theoretical calculations and experimental results, a direct Z-type heterojunction mechanism is proposed for the hydrogen evolution promotion effectiveness of CPDs/ZIS under visible light.

Synthesis of novel solid scale inhibitors based on silver tungstate loaded KIT-6 for scale removal from produced water: static and modeling evaluation

Oilfield scaling is a major problem in the oil and gas industry. Scaling issues cost the industry millions of dollars in damage and lost production every year as scaling is one of the main causes of global production decline. In this study, solid scale inhibitors based on silver tungstate loaded KIT-6 were synthesized and evaluated using a static scale inhibition test. The synthesized materials were characterized using wide and low XRD, N2 adsorption-desorption, TGA, and FTIR, SEM, and XPS analyses. Small-angle XRD patterns showed that KIT-6 had 3D-mesopore diffraction peaks with a cubic Ia3d space group. Wide-angle XRD patterns of silver tungstate loaded KIT-6 confirmed the crystallinity. The prepared catalysts are characterized by higher surface areas (394-918 m2 g-1), large pore volumes (0.63-0.98 cm3 g-1), narrow pore size distributions (5.3 nm), and high thermal stability up to 1000 °C. The results of this study demonstrate that the inhibition efficiency of the scale inhibitor increases and that of the calcite scale inhibitor decreases with increasing pH (2 to 8). This proposes that the scale inhibitor is more effective under alkaline conditions. An inhibition efficiency of 99% on calcium carbonate can be achieved at an optimal dosage of 7.5 ppm at 55 °C, indicating that the scale inhibitor exhibits a relatively good inhibition performance on calcium carbonate. The use of these materials can potentially lead to more efficient and cost-effective solutions for scale inhibition in various industrial processes.

Transition metal compounds: From properties, applications to wettability regulation

Transition metal compounds (TMCs) have the advantages of abundant reserves, low cost, non-toxic and pollution-free, and have attracted wide attention in recent years. With the development of two-dimensional layered materials, a new two-dimensional transition metal carbonitride (MXene) has attracted extensive attention due to its excellent physicochemical properties such as gas selectivity, photocatalytic properties, electromagnetic interference shielding and photothermal properties. They are widely used in gas sensors, oil/water separation, wastewater and waste-oil treatment, cancer treatment, seawater desalination, strain sensors, medical materials and some energy storage materials. In this view, we aim to emphatically summarize MXene with their properties, applications and their wettability regulation in different applications. In addition, the properties of transition metal oxides (TMOs) and other TMCs and their wettability regulation applications are also discussed.

Penta-MP5 (M = B, Al, Ga, In) monolayers as high-performance photocatalysts for overall water splitting

Two-dimensional (2D) phosphorus-rich phosphides generally preserve the excellent electronic properties of phosphorene, making them promising photocatalysts for water splitting. Despite tremendous efforts in the search for potential photocatalysts in 2D phosphides, few known 2D phosphides fully meet the requirements for photocatalytic water splitting. Herein, we systemically investigate a set of penta-MP5 (M = B, Al, Ga, and In) monolayers by first-principles calculations and identify them as potential photocatalysts for water splitting. These penta-MP5 monolayers are found to feature favorable bandgaps of about 2.70 eV with appropriate band edge positions, a high carrier mobility of 1 × 104 cm-2 V-1 s-1, an excellent optical absorption coefficient (OAC) of 1 × 105 cm-1, and a good solar-to-hydrogen (STH) efficiency of 8%. Meanwhile, free energy calculations indicate that these penta-MP5 monolayers present both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) photocatalytic activities under light conditions. All these excellent properties demonstrate that penta-MP5 monolayers are suitable candidates as photocatalysts for promising applications in overall water splitting.

Construction of 2D/2D Mesoporous WO3/CeO2 Laminated Heterojunctions for Optimized Photocatalytic Performance

Photocatalytic elimination of antibiotics from the environment and drinking water is of great significance for human health. However, the efficiency of photoremoval of antibiotics such as tetracycline is severely limited by the prompt recombination of electron holes and slow charge migration efficacy. Fabrication of low-dimensional heterojunction composites is an efficient method for shortening charge carrier migration distance and enhancing charge transfer efficiency. Herein, 2D/2D mesoporous WO₃/CeO₂ laminated Z-scheme heterojunctions were successfully prepared using a two-step hydrothermal process. The mesoporous structure of the composites was proved by nitrogen sorption isotherms, in which sorption-desorption hysteresis was observed. The intimate contact and charge transfer mechanism between WO₃ nanoplates and CeO₂ nanosheets was investigated using high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy measurements, respectively. Photocatalytic tetracycline degradation efficiency was noticeably promoted by the formation of 2D/2D laminated heterojunctions. The improved photocatalytic activity could be attributed to the formation of Z-scheme laminated heterostructure and 2D morphology favoring spatial charge separation, confirmed by various characterizations. The optimized 5WO₃/CeO₂ (5 wt.% WO₃) composites can degrade more than 99% of tetracycline in 80 min, achieving a peak TC photodegradation efficiency of 0.0482 min^-1, which is approximately 3.4 times that of pristine CeO₂. A Z-scheme mechanism is proposed for photocatalytic tetracycline by from WO₃/CeO₂ Z-scheme laminated heterojunctions based on the experimental results.

Shaddock peel-derived N-doped carbon quantum dots coupled with ultrathin BiOBr square nanosheets with boosted visible light response for high-efficiency photodegradation of RhB

In the present work, we constructed a serials of novel shaddock peel-derived N-doped carbon quantum dots (NCQDs) coupled with BiOBr composites. The result showed that the as-synthesized BiOBr (BOB) was composed of ultrathin square nanosheets and flower-like structure, and NCQDs were uniformly dispersed on the surface of BiOBr. Furthermore, the BOB@NCQDs-5 with optimal NCQDs content displayed the top-flight photodegradation efficiency with ca. 99% of removal rate within 20 min under visible light and possessed excellent recyclability and photostability after 5 cycles. The reason was attributed to relatively large BET surface area, the narrow energy gap, inhibited recombination of charge carriers and excellent photoelectrochemical performances. Meanwhile, the improved photodegradation mechanism and possible reaction pathways were also elucidated in detail. On this basis, the study opens a novel perspective to obtain a highly efficient photocatalyst for practical environment remediation.

Application of Micro-Arc Discharges during Anodization of Tantalum for Synthesis of Photocatalytic Active Ta2O5 Coatings

Ta₂O₅ coatings were created using micro-arc discharges (MDs) during anodization on a tantalum substrate in a sodium phosphate electrolyte (10 g/L Na₃PO₄·10H₂O). During the process, the size of MDs increases while the number of MDs decreases. The elements and their ionization states present in MDs were identified using optical emission spectroscopy. The hydrogen Balmer line H_β shape analysis revealed the presence of two types of MDs, with estimated electron number densities of around 1.1 × 10²¹ m^-3 and 7.3 × 10²¹ m^-3. The effect of MDs duration on surface morphology, phase and chemical composition, optical absorption, and photoluminescent, properties of Ta₂O₅ coatings, as well as their applications in photocatalytic degradation of methyl orange, were investigated. The created coatings were crystalline and were primarily composed of Ta₂O₅ orthorhombic phase. Since Ta₂O₅ coatings feature strong absorption in the ultraviolet light region below 320 nm, their photocatalytic activity is very high and increases with the time of the MDs process. This was associated with an increase of oxygen vacancy defects in coatings formed during the MDs, which was confirmed by photoluminescent measurements. The photocatalytic activity after 8 h of irradiation was around 69%, 74%, 80%, and 88% for Ta₂O₅ coatings created after 3 min, 5 min, 10 min, and 15 min, respectively.

Anchored Cu single atoms on porous g-C3N4 for superior photocatalytic H2 evolution from water splitting

One of the most promising strategies for producing hydrogen is photocatalytic water splitting, in which the photocatalyst is a key component. Among many semiconductor photocatalysts, g-C₃N₄ has attracted great attention due to its narrow band gap, excellent stability and low cost. However, practical application is limited by its poor intrinsic activity. In this work, a high-performance porous g-C₃N₄ (PCN) photocatalyst with anchored Cu single atoms (CuSAs) was synthesized by a one-step co-heating approach. The obtained Cu1.5-PCN displays an excellent hydrogen evolution rate (HER) of 2142.4 μmol h^-1 g^-1 under visible light (=420 nm), which is around 15 and 109 times higher than those of PCN and bulk g-C₃N₄, respectively. In addition, it also shows good stability during H₂ evolution. The results of experimental research and DFT simulations indicate that the single Cu ions formed bonds with the N-ring and these remain stable. Meanwhile, the special electronic structure of the Cu-N charge bridge extends the light absorption band to the visible-light region (380-700 nm). This high-performance and low-cost photocatalyst has great potential in solar energy conversion.

Regulation of the Work Function Difference Promotes In Situ Phase Transition of WO3-x for Efficient Formate Electrooxidation

Direct formate fuel cells (DFFCs) have drawn tremendous attention because they are environmentally benign and have good safety. However, the lack of advanced catalysts for formate electrooxidation hinders the development and applications of DFFCs. Herein, we report a strategy of regulating the metal-substrate work function difference to effectively promote the transfer of adsorbed hydrogen (Had), thus enhancing formate electrooxidation in alkaline solutions. By introducing rich oxygen vacancies, the obtained catalysts of Pd/WO3-x-R show outstanding formate electrooxidation activity, exhibiting an extremely high peak current of 15.50 mA cm-2 with a lower peak potential of 0.63 V. In situ electrochemical Fourier transform infrared and in situ Raman measurements verify an enhanced in situ phase transition from WO3-x to HxWO3-x during the formate oxidation reaction process over the Pd/WO3-x-R catalyst. The results of experimental and density functional theory (DFT) calculations confirm that the work function difference (ΔΦ) between the metal (Pd) and substrate (WO3-x) would be regulated by inducing oxygen vacancies in the substrate, resulting in improved hydrogen spillover at the interface of the catalyst, which is essentially responsible for the observed high performance of formate oxidation. Our findings provide a novel strategy of rationally designing efficient formate electrooxidation catalysts.

Interfacial engineering of Ti3C2 MXene/CdIn2S4 Schottky heterojunctions for boosting visible-light H2 evolution and Cr(VI) reduction

Developing efficient heterojunction photocatalysts that have a high charge carrier separation rate and improved light-harvesting capacity is a crucial step in solving energy crisis and reducing environmental pollution. Herein, we synthesized few-layered Ti₃C₂ MXene sheets (MXs) by a manual shaking process, and combined with CdIn₂S₄ (CIS) to construct novel Ti₃C₂ MXene/CdIn₂S₄ (MXCIS) Schottky heterojunction through a solvothermal method. The strong interface between two-dimensional (2D) Ti₃C₂ MXene and 2D CIS nanoplates led to enhanced light-harvesting capacity and promoted charge separation rate. Additionally, the presence of S vacancies on the MXCIS surface helped to trap free electrons. The optimal sample, 5-MXCIS (with 5 wt% MXs loading), exhibited outstanding performance for photocatalytic hydrogen (H₂) evolution and Cr(VI) reduction under visible light due to the synergistic effect of enhanced light-harvesting capacity and charge separation rate. The charge transfer kinetics was thoroughly studied using multiple techniques. The reactive species of ^•O₂^-, ^•OH and h⁺ were generated in 5-MXCIS system, and e^- and ^•O₂^- radicals were found to be the main contributors to Cr(VI) photoreduction. Based on the characterization results, a possible photocatalytic mechanism for H₂ evolution and Cr(VI) reduction was proposed. On the whole, this work provides new insights into the design of 2D/2D MXene-based Schottky heterojunction photocatalysts for boosting photocatalytic efficiency.

Construction of an S-scheme TiOF2/HTiOF3 heterostructures with abundant OVs and OH groups: Performance, kinetics and mechanism insight

Developing efficient photocatalysts is of crucial significance for the development of photocatalysis techniques. In this work, an S-scheme alkaline-washed TiOF₂/HTiOF₃(OHTOF) heterostructures with abundant Oxygen vacancies (Ovs) and OH groups was successfully constructed and used to remedy antibiotic wastewater under simulated sunlight. The generation of HTiOF₃ was induced by g-C₃N₄ regulation. The results displayed that OHTOF15 composite possessed the best photocatalytic performance, which could degrade 94.2% tetracyclinehydrochloride (TCH) at a rate speed constant of 1.077 min^-1 in 2.5 h. The after-alkali-washing process increased the concentration of OH groups and Ovs defects, and greatly enlarged the surface area. The abundant Ovs and OH groups were conducive to the formation of free radicals' and the transport of charge carriers. Compared with the pristine TiOF₂, the absorption sidebands of OHTOF series were greatly red-shifted, which indicated that the increase of OH groups and the etching of the morphology of OHTOF further enhanced its visible-light harvesting ability. Furthermore, the metal cycle of the variable state of Ti⁴⁺/Ti³⁺ in OHTOF15 compensated for the charge balance and promoted the efficient separation of the carriers. Additionally, the apparent quantum efficiency (AQE) of the TCH photodegradation system based on Chemical Oxygen Demand (COD) removal efficiency was calculated to be 0.32%. It was confirmed that the electron transport path in TiOF₂/HTiOF₃ nanocomposites system followed the S-scheme type, which increased the charge carriers' separation rate and maintained a strong redox capacity. This work could provide some enlightenment for the construction of the semiconducting heterojunction and controllable surface defects engineering.

Photocatalytic Synthesis of Materials for Regenerative Medicine Using Complex Oxides with β-pyrochlore Structure

Graft copolymerization of methyl methacrylate onto cod collagen was carried out under visible light irradiation (λ = 400-700 nm) at 20-25 °C using the RbTe_1.5W_0.5O₆, CsTeMoO₆, and RbNbTeO₆ complex oxides with β-pyrochlore structure as photocatalysts. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. It was also found that RbNbTeO₆ with β-pyrochlore structure was not able to photocatalyze the reaction. Enzymatic hydrolysis of the obtained graft copolymers proceeds with the formation of peptides with a molecular weight (MW) of about 20 and 10 kDa. In contrast to collagen, which decomposes predominantly to peptides with MW of about 10 kDa, the ratio of fractions with MW of about 10 kDa and 20 kDa differs much less, their changes are symbatic, and the content of polymers with MW of more than 20 kDa is about 70% after 1 h in the case of graft copolymers. The data obtained indicate that synthetic fragments grafted to the collagen macromolecule do not prevent the hydrolysis of the peptide bonds but change the rate of polymer degradation. This is important for creating network matrix scaffolds based on graft copolymers by cross-linking peptides, which are products of enzymatic hydrolysis.

Heterogeneous photocatalytic oxidation for the removal of organophosphorus pollutants from aqueous solutions: A review

Organophosphorus pollutants (OPs), which are compounds containing carbon‑phosphorus bonds or phosphate derivatives containing organic groups, have received much attention from researchers because of their persistence in the aqueous environment for long periods of time and the threat they pose to human health. Heterogeneous photocatalysis has been widely applied to the removal of OPs from aqueous solutions due to its better removal effect and environmental friendliness. In this review, the removal of OPs from aqueous matrices by heterogeneous photocatalysis was presented. Herein, the application and the heterogeneous photocatalysis mechanism of OPs were described in detail, and the effects of catalyst types on degradation effect are discussed categorically. In particular, the heterojunction type photocatalyst has the most excellent effect. After that, the photocatalytic degradation pathways of several OPs were summarized, focusing on the organophosphorus pesticides and organophosphorus flame retardants, such as methyl parathion, dichlorvos, dimethoate and chlorpyrifos. The toxicity changes during degradation were evaluated, indicating that the photocatalytic process could effectively reduce the toxicity of OPs. Additionally, the effects of common water matrices on heterogeneous photocatalytic degradation of OPs were also presented. Finally, the challenges and perspectives of heterogeneous photocatalysis removal of OPs are summarized and presented.

Experimental and ab initio studies on the structural, magnetic, photocatalytic, and antibacterial properties of Cu-doped ZnO nanoparticles

Copper-doped ZnO nanoparticles with a dopant concentration varying from 1-7 mol% were synthesized and their structural, magnetic, and photocatalytic properties were studied using XRD, TEM, SQUID magnetometry, EPR, UV-vis spectroscopy, and first-principles methods within the framework of density functional theory (DFT). Structural analysis indicated highly crystalline Cu-doped ZnO nanoparticles with a hexagonal wurtzite structure, irrespective of the dopant concentration. EDX and EPR studies indicated the incorporation of doped Cu2+ ions in the host ZnO lattice. The photocatalytic activities of the Cu-doped ZnO nanoparticles investigated through the degradation of methylene blue demonstrated an enhancement in photocatalytic activity as the degradation rate changed from 9.89 × 10-4 M min-1 to 4.98 × 10-2 M min-1. By the first-principles method, our results indicated that the Cu(3d) orbital was strongly hybridized with the O(2p) state below the valence band maximum (VBM) due to covalent bonding, and the ground states of the Cu-doped ZnO is favorable for the ferromagnetic state by the asymmetry of majority and minority states due to the presence of unpaired electron.

Tungsten-based Nanomaterials in the Biomedical Field: A Bibliometric Analysis of Research Progress and Prospects

Tungsten-based nanomaterials (TNMs) with diverse nanostructures and unique physicochemical properties have been widely applied in the biomedical field. Although various reviews have described the application of TNMs in specific biomedical fields, there are still no comprehensive studies that summarize and analyze research trends of the field as a whole. To identify and further promote the development of biomedical TNMs, a bibliometric analysis method is used to analyze all relevant literature on this topic. First, general bibliometric distributions of the dataset by year, country, institute, referenced source, and research hotspots are recognized. Next, a comprehensive review of the subjectively recognized research hotspots in various biomedical fields, including biological sensing, anticancer treatments, antibacterials, and toxicity evaluation, is provided. Finally, the prospects and challenges of TNMs are discussed to provide a new perspective for further promoting their development in biomedical research.

Fabrication of g-C3N4@Bi2MoO6@AgI floating sponge for photocatalytic inactivation of Microcystis aeruginosa under visible light

In this work, a floating photocatalyst was constructed by loading g-C₃N₄@Bi₂MoO₆@AgI (GBA) nanocomposite on a modified polyurethane sponge via a simple dip-coating method and applied for the inactivation of Microcystis aeruginosa under visible light. GBA ternary photocatalyst was fabricated successfully and the morphology, structure, chemical state, and optical properties were characterized systematically. The floating catalyst achieved near 100% removal efficiency of algae cells under 6 h visible light irradiation and also could be retrieved and used at least three times repeatedly. The influences of various conditions on photocatalytic performance such as loading content of nanoparticles, algae density, and concentration of natural organic matters were also studied, which revealed that the GBA floating catalyst exhibited excellent photocatalytic performance of algae removal under different conditions. Furthermore, the physiological characteristics of algae cells during the photocatalytic process, including cell morphology, membrane permeability, Zeta potential, photosynthetic system, antioxidant system, and the metabolic activity were investigated. Results confirmed that the algae cells were severely damaged during the photocatalytic inactivation and the normal physiological functions were significantly affected, which resulted in the death of algae cells at last. Finally, a possible photocatalytic inactivation mechanism of algae cells was proposed. In summary, GBA floating catalyst can effectively inactivate Microcystis aeruginosa under visible light, which confirmed the high efficiency of the novel photocatalytic algae removal technology. Meanwhile, the recyclable floating material also makes the practical application in eutrophic waters of the algae removal technology possible.

Tungsten oxide supported on copper ferrite: a novel magnetic acid heterogeneous catalyst for biodiesel production from low quality feedstock

This study aims to synthesize a WO3/CuFe2O4 catalyst through a wet impregnation method and use it as a new magnetic acid catalyst in the transesterification process of waste cooking oil (WCO). The results of the characterization by XRD, FTIR, SEM, EDS, TG/DTG, VSM and Surface Acidity showed that the obtained bifunctional catalyst has been successfully synthesized. The study of the reaction parameters, such as reaction temperature (140-180 °C), reaction time (1-5 h), molar ratio MeOH : oil (25 : 1-45 : 1) and catalyst loading (2-10% m m-1) was performed in the conversion of WCO into biodiesel via transesterification. The reactional behavior showed the following optimal reaction conditions: reaction temperature of 180 °C, reaction time of 3 h, molar ratio MeOH : oil of 45 : 1 and catalyst loading of 6%. Based on the results, biodiesel with a maximum ester content of 95.2% was obtained using the WO3/CuFe2O4 magnetic catalyst under the optimal reaction conditions. The magnetic catalyst showed excellent catalytic and magnetic performance and it was applied in five reaction cycles with ester content above 80%. Biodiesel properties were found in accordance with ASTM limits. This research provided the development of a stable and reusable WO3/CuFe2O4 bifunctional catalyst for potential application in biodiesel production.

Construction of WO3 nanocubes@Loess for rapid photocatalytic degradation of organics in wastewater under sunlight

In nowadays, environmental pollution has been greatly improved, but the development of low-cost and environmentally friendly materials are still challenge in the field of water treatment. Herein, a cheap and eco-friendly natural loess particle (LoP) was used for in situ growth of tungsten trioxide nanocubes (WO3NCs) on its surface via a simple one-pot hydrothermal method, which afforded a stable loess-based photocatalyst (WO3NCs@LoP). It was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) analysis, UV-Vis diffuse reflectance spectra (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performances of WO3NCs@LoP were applied to photodegradation of organics under visible-light illumination. It was found that the removal rate of methylene blue (MB) got to 99% within 20 min, which was higher than that of materials, such as pure LoP and WO3NCs. Moreover, the photocatalytic activity of WO3NCs@LoP remained 85% after 9 cycling times, indicating its high stability and reusability. It was suggested that the synergy of the well narrowed band gap and effectual control of e--h+ recombination in WO3NCs@LoP improve its photodegradation efficiency. In summary, using natural minerals (LoP) as carrier, a novel eco-friendly photocatalyst could be explored for photodegradation of organic pollutions in wastewater treatment.

Robust Porous TiN Layer for Improved Oxygen Evolution Reaction Performance

The poor reversibility and slow reaction kinetics of catalytic materials seriously hinder the industrialization process of proton exchange membrane (PEM) water electrolysis. It is necessary to develop high-performance and low-cost electrocatalysts to reduce the loss of reaction kinetics. In this study, a novel catalyst support featured with porous surface structure and good electronic conductivity was successfully prepared by surface modification via a thermal nitriding method under ammonia atmosphere. The morphology and composition characterization-confirmed that a TiN layer with granular porous structure and internal pore-like defects was established on the Ti sheet. Meanwhile, the conductivity measurements showed that the in-plane electronic conductivity of the as-developed material increased significantly to 120.8 S cm−1. After IrOx was loaded on the prepared TiN-Ti support, better dispersion of the active phase IrOx, lower ohmic resistance, and faster charge transfer resistance were verified, and accordingly, more accessible catalytic active sites on the catalytic interface were developed as revealed by the electrochemical characterizations. Compared with the IrOx/Ti, the as-obtained IrOx/TiN-Ti catalyst demonstrated remarkable electrocatalytic activity (η10 mA cm−2 = 302 mV) and superior stability (overpotential degradation rate: 0.067 mV h−1) probably due to the enhanced mass adsorption and transport, good dispersion of the supported active phase IrOx, increased electronic conductivity and improved corrosion resistance provided by the TiN-Ti support.

Altered zirconium dioxide based photocatalyst for enhancement of organic pollutants degradation: A review

Heterogeneous advanced oxidation processes are a promising approach for cost-efficient removal of pollutants using semiconductors. Zirconium dioxide (ZrO₂) is an auspicious material for photocatalytic activity owning to its suitable bandgap, stability, and low cost. However, ZrO₂ suffers from fast recombination rate, and poor light harvesting ability. Nonetheless, extra modification has also shown improvements and therefore is worth investigating. The endeavour of this paper initially discusses the fundamentals with respect to reactive species, classification, and synthesis methods for ZrO₂. Furthermore, with particular consideration to stability and reusability, several additional modification approaches for ZrO₂-based photocatalysts such as doping and noble metals loading. Furthermore, the formation of heterojunctions has also been shown to boost photocatalytic activity while inhibiting charge carrier recombination. Finally, photocatalyst separation via magnetic-based photocatalysts are elucidated. As a result, ZrO₂-based photocatalysts are regarded as a promising emerging technology that warrants further development and research.

Efficient degradation of VOCs using semi-coke activated carbon loaded ternary Z-scheme heterojunction photocatalyst BiVO4-BiPO4-g-C3N4 under visible light irradiation

The coal chemical industry generates large amounts of solid waste and volatile organic compounds (VOCs). In this study, the solid waste semi-coke powder obtained in the semi-coke production process was used as a raw material to prepare high-specific surface area semi-coke activated carbon (SAC) by a carbonization and activation process, and a ternary z-scheme heterojunction photocatalyst with high catalytic performance was loaded for synergistic treatment by adsorption and photodegradation to achieve waste treatment with waste. The prepared semi-coke activated carbon has a specific surface area of 619.27 m² g^-1, which can achieve effective adsorption of VOCs. The ternary z-scheme heterojunction photocatalyst BiPO₄-BiVO₄-g-C₃N₄ (PVCN) was supported on a semi-coke activated carbon substrate by a one-step sol-gel method. Based on the synergistic effect of adsorption and photocatalysis, the obtained PVCN/SAC material can degrade toluene by 85.6% within 130 minutes under simulated sunlight irradiation, which is 2.43 times that of pure photocatalyst. The rate of degrading toluene can be increased by 4.43 times. Capture experiments showed that superoxide radicals (_˙O₂^-) and hydroxyl radicals (_˙OH) were the key active species in the degradation pathway. Even after five cycles, the material maintained 81.6% of the degradation performance. In this work, we deeply investigate the mechanism of semi-coke activated carbon as a matrix for enhancing photocatalytic degradation performance. The findings of this work provide new insights into the efficient degradation of VOCs and provide a good theoretical basis for the development of high-performance photocatalysts.

Photocatalytic Water Splitting Promoted by 2D and 3D Porphyrin Covalent Organic Polymers Synthesized by Suzuki-Miyaura Carbon-Carbon Coupling

This work deals with the synthesis of metal-free and porphyrin-based covalent organic polymers (COPs) by the Suzuki-Miyaura coupling carbon-carbon bond forming reaction to study the photocatalytic overall water splitting performance. Apart from using 5,10,15,20-Tetrakis-(4-bromophenyl)porphyrin, we have chosen different cross-linker monomers to induce 2-dimensional (2D) or 3-dimensional (3D) and different rigidity in their resulting polymeric molecular structure. The synthesised COPs were extensively characterised to reveal that the dimensionality and flexibility of the molecular structure play an intense role in the physical, photochemical, and electronic properties of the polymers. Photoinduced excited state of the COPs was evaluated by nanosecond time-resolved laser transient absorption spectroscopy (TAS) by analysing excited state kinetics and quenching experiments, photocurrent density measurements and photocatalytic deposition of Ru³⁺ to RuO_2, and photocatalysis. In summary, TAS experiments demonstrated that the transient excited state of these polymers has two decay kinetics and exhibit strong interaction with water molecules. Moreover, photocurrent and photocatalytic deposition experiments proved that charges are photoinduced and are found across the COP molecular network, but more important charges can migrate from the surface of the COP to the medium. Among the various COPs tested, COP-3 that has a flexible and 3D molecular structure reached the best photocatalytic performances, achieving a photocatalytic yield of 0.4 mmol H₂ × g_COP-3^-1 after 3 h irradiation.

In Situ Coupling Carbon Defective C3N5 Nanosheet with Ag2CO3 for Effective Degradation of Methylene Blue and Tetracycline Hydrochloride

The development of novel catalysts for degrading organic contaminants in water is a current hot topic in photocatalysis research for environmental protection. In this study, C₃N₅ nanosheet/Ag₂CO₃ nanocomposites (CNAC-X) were used as efficient photocatalysts for the visible-light-driven degradation of methylene blue (MB), and tetracycline hydrochloride (TC-HCl) was synthesized for the first time using a simple thermal oxidative exfoliation and in situ deposition method. Due to the synergistic effect of nanosheet structures, carbon defects, and Z-scheme heterojunctions, CNAC-10 exhibited the highest photocatalytic activity, with photodegradation efficiencies of 96.5% and 97.6% for MB (60 mg/L) and TC-HCl (50 mg/L) within 90 and 100 min, respectively. The radical trapping experiments showed that ·O₂^- and h⁺ played major roles in the photocatalytic effect of the CNAC-10 system. Furthermore, intermediates in the photodegradation of MB and TC-HCl were investigated to determine possible mineralization pathways. The results indicated that C₃N₅ nanosheet/Ag₂CO₃ photocatalysts prepared in this work could provide an effective reference for the treatment of organic wastewater.

Improving Photoelectrochemical Activity of Magnetron-Sputtered Double-Layer Tungsten Trioxide Photoanodes by Irradiation with Intense Pulsed Ion Beams

The photoelectrochemical (PEC) activity of metal oxide photoelectrodes for water-splitting applications can be boosted in several different ways. In this study, we showed that PEC activity can be significantly improved with a double-layer (crystalline-amorphous) configuration of WO₃ thin films irradiated with intense pulsed ion beams (IPIB) of a nanosecond duration. It was found that IPIB irradiation promotes the formation of crystalline and sponge-like WO₃ structures on the surface. Due to an increase in the active surface and light scattering in irradiated samples, photocurrent generation increased by ~80% at 1.23 reversible hydrogen electrodes (RHE).

Recent advances in visible-light graphitic carbon nitride (g-C3N4) photocatalysts for chemical transformations

Graphitic carbon nitride (g-C3N4) has emerged as a new research hotspot, attracting broad interdisciplinary attention in the form of metal-free and visible-light-responsive photocatalysts in the field of solar energy conversion and environmental remediation. These photocatalysts have evolved as attractive candidates due to their non-toxicity, chemical stability, efficient light absorption capacity in the visible and near-infrared regions, and adaptability as a platform for the fabrication of hybrid materials. This review mainly describes the latest advances in g-C3N4 photocatalysts for chemical transformations. In addition, the typical applications of g-C3N4-based photocatalysts involving organic transformation reactions are discussed (synthesis of heterocycles, hydrosulfonylation, hydration, oxygenation, arylation, coupling reactions, etc.).

Photocatalytic hydrogen production and storage in carbon nanotubes: a first-principles study

As it is a promising clean energy source, the production and storage of hydrogen are crucial techniques. Here, based on first-principles calculations, we proposed an integral strategy for the production and storage of hydrogen in carbon nanotubes via photocatalytic processes. We considered a core–shell structure formed by placing a carbon nitride nanowire inside a carbon nanotube to achieve this goal. Photo-generated holes on the carbon nanotube surface promote water splitting. Driven by intrinsic electrostatic field in the core–shell structures, protons produced by water splitting penetrate the carbon nanotube and react with photo-generated electrons on the carbon nitride nanowire to produce hydrogen molecules in the carbon nanotube. Because carbon nanotubes have high hydrogen storage capacity, this core–shell structure can serve as a candidate system for photocatalytic water splitting and safe hydrogen storage.

The production and storage of hydrogen in CNNW/CNT core–shell structures via photocatalytic processes.

Enhanced photocatalytic H2 evolution over covalent organic frameworks through an assembled NiS cocatalyst

Covalent organic frameworks (COFs) have been investigated in the field of photocatalysts for H₂ evolution because of their crystalline structure and diversity. However, most of them need the help of noble metals as co-catalysts to realize a high hydrogen evolution. Herein, we chose typical COFs as a platform and constructed NiSX-BD (X: weight fraction of NiS) composites by assembling NiS at room temperature. The NiS nanoparticles are shown to tightly adhere to the COFs surface. Under visible light irradiation (wavelength > 420 nm), the optimized sample with 3 wt% NiS loading exhibits a photocatalytic H₂ evolution rate of 38.4 μmol h⁻¹ (3840 μmol h⁻¹ g⁻¹), which is about 120 folds higher than that of the pure TpBD-COF and better than TpBD-COF/Pt with the same Pt loading (3 wt%). NiS3-BD shows stable hydrogen evolution in at least six consecutive cycle tests totaling 18 h. Further investigation reveals that the loaded NiS can facilitate the transfer of photogenerated electrons from TpBD-COF to the co-catalyst, leading to efficient and high photocatalytic activity. Combining the significant feature of COFs, this study opens up a feasible avenue to boost the photocatalytic H₂ performance by constructing the synergetic effects between COFs and cost-effective material.

We constructed a novel hybrid photocatalyst by assembling NiS through a milder method. Under visible light irradiation, controlled NiS/TpBD-COF composites can readily optimize photocatalytic performances without a noble cocatalyst.

Electrochemical Synthesis-Dependent Photoelectrochemical Properties of Tungsten Oxide Powders

A rapid, facile, and environmentally benign strategy to electrochemical oxidation of metallic tungsten under pulse alternating current in an aqueous electrolyte solution was reported. Particle size, morphology, and electronic structure of the obtained WO3 nanopowders showed strong dependence on electrolyte composition (nitric, sulfuric, and oxalic acid). The use of oxalic acid as an electrolyte provides a gram-scale synthesis of WO3 nanopowders with tungsten electrochemical oxidation rate of up to 0.31 g·cm−2·h−1 that is much higher compared to the strong acids. The materials were examined as photoanodes in photoelectrochemical reforming of organic substances under solar light. WO3 synthesized in oxalic acid is shown to exhibit excellent activity towards the photoelectrochemical reforming of glucose and ethylene glycol, with photocurrents that are nearly equal to those achieved in the presence of simple alcohol such as ethanol. This work demonstrates the promise of pulse alternating current electrosynthesis in oxalic acid as an efficient and sustainable method to produce WO3 nanopowders for photoelectrochemical applications.

Synthesis, Characterization, Photocatalysis, and Antibacterial Study of WO3, MXene and WO3/MXene Nanocomposite

Tungsten oxide (WO₃), MXene, and an WO₃/MXene nanocomposite were synthesized to study their photocatalytic and biological applications. Tungsten oxide was synthesized by an easy and cost-effective hydrothermal method, and its composite with MXene was prepared through the sonication method. The synthesized tungsten oxide, MXene, and its composite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), energy-dispersive X-ray analysis (EDX), and Brunauer–Emmett–Teller (BET) for their structural, morphological, spectral, elemental and surface area analysis, respectively. The crystallite size of WO₃ calculated from XRD was ~10 nm, the particle size of WO₃ was 130 nm, and the average thickness of MXene layers was 175 nm, which was calculated from FESEM. The photocatalytic activity of as-synthesized samples was carried out for the degradation of methylene blue under solar radiation, MXene, the WO₃/MXene composite, and WO₃ exhibited 54%, 89%, and 99% photocatalytic degradation, respectively. WO₃ showed maximal degradation ability; by adding WO₃ to MXene, the degradation ability of MXene was enhanced. Studies on antibacterial activity demonstrated that these samples are good antibacterial agents against positive strains, and their antibacterial activity against negative strains depends upon their concentration. Against positive strains, the WO₃/MXene composite’s inhibition zone was at 7 mm, while it became 9 mm upon increasing the concentration. This study proves that WO₃, MXene, and the WO₃/MXene nanocomposite could be used in biological and environmental applications.

Unveiling the charge transfer behavior within ZSM-5 and carbon nitride composites for enhanced photocatalytic degradation of methylene blue

ZSM-5/graphitic carbon nitride (g-C₃N₄) composites were successfully prepared using a simple solvothermal method. By varying the amount of ZSM-5 and g-C₃N₄ in the composites, the charge carrier (electrons and holes) transfer within the materials, which contributes to the enhanced photocatalytic performance, was unraveled. The X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM) analysis revealed that more ZSM-5 component leads to a stronger interaction with g-C₃N₄. The photocatalytic performance test toward methylene blue (MB) degradation shows that more ZSM-5 in the composites is beneficial in enhancing photocatalytic activity. Meanwhile, the impedance electron spectroscopy (EIS) and photoluminescence (PL) analysis revealed that ZSM-5 facilitates the charge carrier transfer of photogenerated electrons and holes from g-C₃N₄ to the catalyst surface due to its lower charge transfer resistance. During the charge carrier migration, the interface between g-C₃N₄ and ZSM-5 particles may induce higher resistance for the charge carrier transfer, however after passing through the interface from g-C₃N₄ to ZSM-5 particles, the charge carrier can be efficiently transferred to the surface, hence suppressing the charge carrier recombination.

Review on Nanoparticles and Nanostructured Materials: Bioimaging, Biosensing, Drug Delivery, Tissue Engineering, Antimicrobial, and Agro-Food Applications

In the last few decades, the vast potential of nanomaterials for biomedical and healthcare applications has been extensively investigated. Several case studies demonstrated that nanomaterials can offer solutions to the current challenges of raw materials in the biomedical and healthcare fields. This review describes the different nanoparticles and nanostructured material synthesis approaches and presents some emerging biomedical, healthcare, and agro-food applications. This review focuses on various nanomaterial types (e.g., spherical, nanorods, nanotubes, nanosheets, nanofibers, core-shell, and mesoporous) that can be synthesized from different raw materials and their emerging applications in bioimaging, biosensing, drug delivery, tissue engineering, antimicrobial, and agro-foods. Depending on their morphology (e.g., size, aspect ratio, geometry, porosity), nanomaterials can be used as formulation modifiers, moisturizers, nanofillers, additives, membranes, and films. As toxicological assessment depends on sizes and morphologies, stringent regulation is needed from the testing of efficient nanomaterials dosages. The challenges and perspectives for an industrial breakthrough of nanomaterials are related to the optimization of production and processing conditions.