In Situ Synthesis, Characterization, and Catalytic Performance of Polypyrrole Polymer-Incorporated Ag2MoO4 Nanocomposite for Detection and Degradation of Environmental Pollutants and Pharmaceutical Drugs

Tracking of structural defects induced by Eu-doping in β-Ag2MoO4: their influences on electrical properties

In this study, several methods were employed to investigate the electrical characteristics of β-Ag2MoO4 systems, both Eu-doped and undoped, synthesized using the microwave-assisted hydrothermal method. The focus extended to understanding how synthesis time influences material defects, with doping fixed at 1%. A systematic shift in the silver vacancy (VAg) concentration was observed within the doped β-Ag2MoO4 system. Specifically, this study demonstrated that the incorporation of Eu3+ into polycrystalline β-Ag2MoO4 initially increases the VAg concentration. However, as the synthesis time progresses, the VAg concentration decreases, resulting in alterations in the resulting electrical properties, arising from the intricate interplay between the number of grain boundaries and carrier density. By combining information obtained from photoluminescence, positron annihilation lifetime spectroscopy, and impedance spectroscopy, a comprehensive conduction mechanism was formulated, shedding light on both doped and undoped β-Ag2MoO4 systems.

Novel electrospun bead-like Ag2MoO4 nanofibers coated on Ni foam for visible light-driven heterogeneous photocatalysis and high-performance supercapacitor electrodes

Novel Ag2MoO4 nanocomposite fibers were designed to enhance the photocatalytic response and supercapacitor performance of MoO3 grown via the sol-gel electrospinning technique. The Ag2MoO4 nanocomposite fibers exhibit a high specific surface area of 49.3 m2 g-1 comprising nanobeads that aggregate in the fibrous structure. The photodegradation efficiency of Ag2MoO4 was evaluated as 62% under visible light irradiation which improved to 71% with heterogeneous photocatalysis. The Ag2MoO4@Ni foam exhibited a low Rct of 19.6 Ω, and an enhanced specific capacitance of 1445 F g-1 was obtained at 1 A g-1, with 93% of its initial capacitance remaining after 5000 cycles. In addition, the Ag2MoO4//activated carbon asymmetric supercapacitor possesses an excellent energy density of 76.6 W h kg-1 at 743.2 W kg-1 and a noteworthy cycling durability of 91% after 5000 cycles. Our findings demonstrate that the electrospun Ag2MoO4@Ni foam is an important and inexpensive electrode material for supercapacitor applications and visible light-driven heterogeneous photocatalysis, drawing on the synergic effects of Ag and Mo to exhibit much better performance.

Catalytic polymer nanocomposites for environmental remediation of wastewater

The removal of harmful chemicals and species from water, soil, and air is a major challenge in environmental remediation, and a wide range of materials have been studied in this regard. To identify the optimal material for particular applications, research is still ongoing. Polymer nanocomposites (PNCs), which combine the benefits of nanoparticles with polymers, an alternative to conventional materials, may open up new possibilities to overcome this difficulty. They have remarkable mechanical capabilities and compatibility due to their polymer matrix with a very high surface area to volume ratio brought about by their special physical and chemical properties, and the extremely reactive surfaces of the nanofillers. Composites also provide a viable answer to the separation and reuse problems that hinder nanoparticles in routine use. Understanding these PNCs materials in depth and using them in practical environmental applications is still in the early stages of development. The review article demonstrates a crisp introduction to the PNCs with their advantageous properties as a catalyst in environmental remediation. It also provides a comprehensive explanation of the design procedure and synthesis methods for fabricating PNCs and examines in depth the design methods, principles, and design techniques that guide proper design. Current developments in the use of polymer nanocomposites for the pollutant treatment using three commonly used catalytic processes (catalytic and redox degradation, electrocatalytic degradation, and biocatalytic degradation) are demonstrated in detail. Additionally, significant advances in research on the aforementioned catalytic process and the mechanism by which contaminants are degraded are also amply illustrated. Finally, there is a summary of the research challenges and future prospects of catalytic PNCs in environmental remediation.

Bifunctional quaternary magnetic composite as efficient heterojunctions photocatalyst for simultaneous photocatalytic visible light degradation of dye and herbicide pollutants from water and bacterial disinfection

In the present study, the magnetic Fe3O4/Ag2C2O4/Ag3PO4/Ag nanocomposite were prepared through a simple co-precipitation method by using calendula officinalis seed extract as a stabilizer. The fabricated quaternary photocatalyst was applied for to degrade food dye Brilliant Blue FCF (BB) and herbicide Paraquat (PQ) as contaminants at binary mixture in a batch and continuous flow-loop photoreactor under visible light irradiation and also the antibacterial properties was investigated. The fabricated nanocomposite was determined by XRD, FESEM, EDX, BET&BJH, UV-DRS, FT-IR and VSM methods to gain insight about structure, morphology, purity, surface area, optical, functional group and magnetic properties. The photoelectrochemical experiments, PL and DRS indicate the successful coupling of the active semiconductors. The degradation efficiency of BB and PQ was announced to be 88.9% and 92.72% under optimal conditions with a high reaction rate constant value (0.03 and 0.0326 min-1), respectively. The quaternary photocatalyst exhibited superior photocatalytic performance compared with Ag3PO4/Ag2C2O4 and Ag2C2O4. Various scavengers were used to explore the mechanism of photocatalytic performance and supports that [Formula: see text] and OH. is main active species in the degradation process of BB and PQ, respectively. Furthermore, the Fe3O4/Ag2C2O4/Ag3PO4/Ag also demonstrated bactericidal activity against Staphylococcus aureus (S. aureus) as gram-positive bacteria and Escherichia coli (E. coli) as gram-negative bacteria.

Photo-assisted "co-movement catalysis": CoFe2O4/CNS heterojunction based portable electrochemical sensor for simultaneous detection of Pb2+ and Cd2+ in natural water

Heavy metal ions (HMIs) seriously threaten human health even under trace conditions. Therefore, accurate, efficient and simultaneous detection of multiple HMIs is of great significance. Here, a strategy of "co-movement catalysis" based on photo-assisted electrochemical catalysis is proposed by constructing a flexible electrochemical sensor with CoFe2O4/CNS heterojunction-modified nickel foam as the working electrode for simultaneous detection of HMIs. Regarding photo-assisted catalysis, CoFe2O4/CNS nanocomposites formed a p-n type heterojunction, effectively separating photo-generated electron-hole pairs and reducing photo-generated carriers' recombination rate, leading to the catalytic reaction of photogenerated electrons and holes with HMIs and atoms to improve the efficiency of preconcentration and stripping, further amplifying the electrochemical signal. Regarding electrochemical catalysis, the CoFe2O4 spinel contains variable valence transition metal ions Fe2+/Fe3+ and Co2+/Co3+, which can reduce and oxidize HMIs circularly, further enhancing the sensor's sensitivity. The portable sensor based on "co-movement catalysis" exhibited sensitive detection performance. The linear range is 0.100-10.0 μM for Pb2+ and 1.00-10.0 μM for Cd2+, with the detection limit of 0.0310 μM for Pb2+ and 0.219 μM for Cd2+, respectively. The recovery rate of the sensor to natural water samples is between 96% and 105%, which proves its development potential in environmental monitoring.

In-situ formation of niobium oxide – niobium carbide – reduced graphene oxide ternary nanocomposite as an electrochemical sensor for sensitive detection of anticancer drug methotrexate

Engineering the nanostructure of an electrocatalyst is crucial in developing a high-performance electrochemical sensor. This work exhibits the hydrothermal followed by annealing synthesis of niobium oxide/niobium carbide/reduced graphene oxide (NbO/NbC/rGO) ternary nanocomposite. The oval-shaped NbO/NbC nanoparticles cover the surface of rGO evenly, and the rGO nanosheets are interlinked to produce a micro-flower-like architecture. The NbO/NbC/rGO nanocomposite-modified electrode is presented here for the first time for the rapid and sensitive electrochemical detection of the anticancer drug methotrexate (MTX). Down-sized NbO/NbC nanoparticles and rGO's high surface area provide many active sites with a rapid electron transfer rate, making them ideal for MTX detection. In comparison to previously reported MTX sensors, the developed drug sensor exhibits a lower oxidation potential and a higher peak current responsiveness. The constructed sensors worked analytically well under optimal conditions, as shown by a low detection limit of 1.6 nM, a broad linear range of 0.1-850 µM, and significant recovery findings (∼98 %, (n = 3)) in real samples analysis. Thus, NbO/NbC/rGO nanocomposite material for high-performance electrochemical applications seems promising.

Recent advances in electrochemical-based sensors amplified with carbon-based nanomaterials (CNMs) for sensing pharmaceutical and food pollutants

Foodborne-related infections due to additives and pollutants pose a considerable task for food processing enterprises. Therefore, the competent, cost-effective, and quick investigation of nutrition additives and contaminants is essential to reduce the threat of public fitness problems. The electrochemical sensor (ECS) shows facile and potent analytical approaches desirable for food protection and quality inspection over traditional methods. The consequence of a broad display of nanomaterials has paved the path for their relevance in designing high-performance ECSs appliances for medical diagnostics and conditions and food protection. This review article has discussed the importance of electrochemical-based sensors amplified with carbon-based nanomaterials (CNMs). Initially, we have demonstrated the types of pharmaceutical and food/agriculture pollutants (such as pesticides, heavy metals, antibiotics and other medical drugs) present in water. Subsequently, we have compiled the information on electrochemical techniques (such as voltammetric and electrochemical impedance spectroscopy) and their crucial parameters for detecting pollutants. Further, the applications of CNMs for sensing pharmaceutical and food pollutants have been demonstrated in detail. Finally, the topic has been concluded with existing challenges and future prospects.

Conjugated Polymer Polypyrrole Nanostructures: Synthesis and Photocatalytic Applications

Conjugated polymers (CPs) have been recently widely investigated for their properties and their applications in different fields including photocatalysis. Among the family of CPs, polypyrrole (PPy) has been the most extensively studied owing to its good environmental stability, high electrical conductivity, superior redox properties and easy synthesis. Besides, nanostructured polypyrrole-based nanomaterials are a type of active organic materials for photocatalysis, which is one of their emerging applications. Nanostructuration of polypyrrole can reduce the electron-hole recombination because of short charge transfer distances and reactant adsorption, and product desorption can be enhanced owing to the high surface area offered by nanostructures. This review summarizes synthesis of different nanostructures based on π-conjugated polymer polypyrrole and the latest developments for photocatalytic applications, including degradation of organic pollutants and hydrogen generation.

Engineering an oxygen-vacancy-mediated step-scheme charge carrier dynamic coupling WO3−X/ZnFe2O4 heterojunction for robust photo-Fenton-driven levofloxacin detoxification

Schematic representation of the photo-Fenton degradation of levofloxacin under solar-light illumination.

Conducting polymers/zinc oxide-based photocatalysts for environmental remediation: a review

The accessibility to clean water is essential for humans, yet nearly 250 million people die yearly due to contamination by cholera, dysentery, arsenicosis, hepatitis A, polio, typhoid fever, schistosomiasis, malaria, and lead poisoning, according to the World Health Organization. Therefore, advanced materials and techniques are needed to remove contaminants. Here, we review nanohybrids combining conducting polymers and zinc oxide for the photocatalytic purification of waters, with focus on in situ polymerization, template synthesis, sol-gel method, and mixing of semiconductors. Advantages include less corrosion of zinc oxide, less charge recombination and more visible light absorption, up to 53%.

Silver nanomaterials: synthesis and (electro/photo) catalytic applications

In view of their unique characteristics and properties, silver nanomaterials (Ag NMs) have been used not only in the field of nanomedicine but also for diverse advanced catalytic technologies. In this comprehensive review, light is shed on general synthetic approaches encompassing chemical reduction, sonochemical, microwave, and thermal treatment among the preparative methods for the syntheses of Ag-based NMs and their catalytic applications. Additionally, some of the latest innovative approaches such as continuous flow integrated with MW and other benign approaches have been emphasized that ultimately pave the way for sustainability. Moreover, the potential applications of emerging Ag NMs, including sub nanomaterials and single atoms, in the field of liquid-phase catalysis, photocatalysis, and electrocatalysis as well as a positive role of Ag NMs in catalytic reactions are meticulously summarized. The scientific interest in the synthesis and applications of Ag NMs lies in the integrated benefits of their catalytic activity, selectivity, stability, and recovery. Therefore, the rise and journey of Ag NM-based catalysts will inspire a new generation of chemists to tailor and design robust catalysts that can effectively tackle major environmental challenges and help to replace noble metals in advanced catalytic applications. This overview concludes by providing future perspectives on the research into Ag NMs in the arena of electrocatalysis and photocatalysis.

In-situ fabrication of novel flower like MoS2/CoTiO3 nanorod heterostructures for the recyclable degradation of ciprofloxacin and bisphenol A under sunlight

Effectual degradation of toxic water contaminants is a crucial step in water purification and designing an efficient semiconductor based hybrid structure photocatalyst is a good approach to achieve this. Benefiting from the combination of semiconductors, a series of novel visible-light active flower-like MoS₂/CoTiO₃ nanorod heterostructures with excellent morphological contact interface were prepared through a facile in-situ hydrothermal process. These heterostructures were well characterized and demonstrated high photocatalytic performance for ciprofloxacin (CIP) and bisphenol A (BPA) under sunlight irradiation. Compared to pristine CoTiO₃ and MoS₂, the optimal catalyst (5 wt% MoS₂/CoTiO₃) presented 39.97 and 22.32 times higher activity for CIP degradation and 26.85 and 15.66 times higher activity for BPA degradation, respectively. This improved activity can be accounted for the effective interfacial contact which promotes the efficient charge carriers separation and reduce its recombination. The catalyst exhibited decent stability and was potentially reused for five cycles without significant loss in activity. Furthermore, based on active species scavenging experiments the plausible photodegradation mechanism is discussed in detail.

Visible light-conducting polymer nanocomposites as efficient photocatalysts for the treatment of organic pollutants in wastewater

This review compiles recent advances and challenges on photocatalytic treatment of wastewater using nanoparticles, nanocomposites, and polymer nanocomposites as photocatalyst. The review provides an overview of the fundamental principles of photocatalytic treatment along the recent advances on photocatalytic treatment, especially on the modification strategies and operational conditions to enhance treatment efficiency and removal of recalcitrant organic contaminants. The different types of photocatalysts along the key factors influencing their performance are also critically discussed and recommendations for future research are provided.

Bismuth molybdate incorporated functionalized carbon nanofiber as an electrocatalytic tool for the pinpoint detection of organic pollutant in life samples

Herein, we fabricated a feasible and accurate sensing platform for the quantification of toxic organic pollutant 2-nitroaniline (2-NA) in water samples through electrocatalyst made up of bismuth molybdate (Bi₂MoO₆, BMO) functionalized carbon nanofiber (f-CNF) modified electrode. The preparation of BMO/f-CNF composite is of two methods, such as co-precipitation (C-BMO/f-CNF) and ultrasonication method (U-BMO/f-CNF). The physicochemical properties of the composites were characterized by XRD, FTIR, Raman, BET, FE-SEM, and HR-TEM techniques. At U-BMO/f-CNF, the charge transfer resistance was low (R_ct = 12.47 Ω) compared to C-BMO/f-CNF because nanosized U-BMO particles correctly aim at the defective sites of the f-CNF surface wall. Further, the electrocatalytic activity of C&U-BMO/f-CNF composites was examined by cyclic voltammetry (CV) and differential pulse voltammetry techniques (DPV) for the electrochemical detection of 2-nitroaniline (2-NA). The U-BMO/f-CNF/GCE shows a higher cathodic current, wide dynamic linear range of 0.01-168.01 µM, and superior electrocatalytic activity with a low detection limit (0.0437 µM) and good sensitivity (0.6857 μA μM^-1 cm^-2). The excellent selectivity nature of U-BMO/f-CNF/GCE was observed in the presence of various organic pollutants and a few toxic metal cations. The practical applicability such as stability, repeatability towards 2-NA outcomes with accepted results. Besides, the practical viability of as proposed U-BMO/f-CNF sensor was investigated in soil and lake water samples delivers good recovery results. Hence from these analyses, we conclude that U-BMO/f-CNF/GCE potential for the determination of hazardous environmental pollutant 2-NA.

Fabrication of a novel ternary heterojunction composite Ag2MoO4/Ag2S/MoS2 with significantly enhanced photocatalytic performance

A novel ternary heterojunction Ag₂MoO₄/Ag₂S/MoS₂ was successfully fabricated via a facile two-step method. The prepared ternary heterojunction showed much enhanced catalytic activity compared with monomers and binary heterojunctions.

Pyrocatalytic oxidation - strong size-dependent poling effect on catalytic activity of pyroelectric BaTiO3 nano- and microparticles

Pyrocatalysis is an emerging advanced oxidation process for wastewater remediation with the potential for thermal energy harvesting and utilization. Although several studies explored the potential of new pyrocatalyst materials to degrade harmful organic water pollutants, the role of important material properties and electric poling procedures on the pyrocatalytic activity is still unclear. In this work, we investigate the interdependence between particle size, electric poling and pyrocatalytic activity of BaTiO3 powders with nominal particle sizes of 100, 200 and 500 nm by using the dichlorofluorescein redox assay. Depending on the particle size, the influence of surface area or phase composition on the pyrocatalytic activity predominates. Moreover, we demonstrate that poling of pyrocatalysts leads to a strong size-dependent increase of pyrocatalytic activity. This poling effect increases with particle size up to +247% and can be explained with size-dependent changes in phase composition and domain structure. Combining all results, the progression of the pyrocatalytic activity as a function of particle size was derived and a future strategy for maximizing the catalytic performance of pyrocatalysts was developed. This study greatly improves the understanding about the role of important material properties and electric poling on pyrocatalytic activity, thus enabling an effective catalyst design. With the help of highly active catalysts, the pyrocatalytic process can take the next step in its development into a new and energy-efficient advanced oxidation process for water remediation.

Deep eutectic solvent-based manganese molybdate nanosheets for sensitive and simultaneous detection of human lethal compounds: comparing the electrochemical performances of M-molybdate (M = Mg, Fe, and Mn) electrocatalysts

Potentially hazardous chemical contaminants endanger the environment and human well-being, challenging scientists and policy makers to develop holistic alternative approaches for remediation. The addition or accumulation of these chemicals can have a series of far-reaching consequences and have direct and indirect effects at multiple levels of ecological organization. Therefore, the development of a sensitive tool for the comprehensive evaluation of chemical concentrations is highly relevant. Herein, we thus report the simultaneous electrochemical detection of highly toxic hydroquinone (HQ), Hg²⁺, and nitrite (NO₂^-) compounds using nanostructured metal molybdate (M = Mg, Fe and Mn) catalysts. These functional nanomaterials are synthesized using a deep eutectic solvent (DES) modified hydrothermal method that provides sustainable aspects and energy efficient synthesis strategies. Choline chloride (ChCl)-urea DES used in this study exhibits an all-in-one behaviour by simultaneously acting as a template, reducing agent, and homogeneous means for stabilizing metal ions. This stimulates the fabrication of hierarchical structures of metal molybdates with high surface activities that cause their remarkable properties with minimal waste generation. The structural, morphological, catalytic, and electrochemical capacities of the as-synthesized MgMoO₄, Fe₂(MoO₄)₃, and MnMoO₄ materials are explored through various techniques and comparatively, MnMoO₄ presents superior characterization features such as a reduced particle size, increased surface area and hierarchical architectures. Owing to the exceptional physicochemical attributes, the MnMoO₄ modified glassy carbon electrode (GCE) demonstrates superior electrochemical activities towards the individual and simultaneous detection of HQ, Hg²⁺, and NO₂^-. Well-defined and separate peaks are observed for the simultaneous detection of HQ, Hg²⁺, and NO₂^- which is influenced by the binding energies of these pollutants. Furthermore, the modified electrode exhibits a high sensitivity of 23.8, 17.7 and 10.2 μA μM^-1 cm^-2 with a limit of detection (LOD) of 0.026, 0.05, and 0.01 μM for HQ, Hg²⁺, and NO₂^- respectively under ideal conditions. Also, the reproducibility and anti-interference ability reinforce the application potential of the MnMoO₄ modified electrode for the simultaneous electrochemical detection of HQ, Hg²⁺, and NO₂^- in real samples with better recoveries, thus assessing the effect of these hazardous chemicals on humanity.

Facile Construction of a Copper-Containing Covalent Bond for Peroxymonosulfate Activation: Efficient Redox Behavior of Copper Species via Electron Transfer Regulation

Heterogeneous catalysis can be enhanced through the construction of effective atom connection for rapid electron transport on the catalyst surface. Hence, this study proposed a new strategy for electron transfer regulation to facilitate redox cycle of Cu(II)/Cu(I). The objective was achieved by successful construction of copper-containing covalent bond through the in situ growth of porous g-C₃N₄ with oxygen dopants and nitrogen defects (O-CN_D) on CuAl_xO_y substrate (CuAl@O-CN_D). On the basis of X-ray absorption fine structure (XAFS) and other characterization results, the facilitated redox behavior of copper species by electron transfer regulation was ascribed to the formation of a C-O-Cu bond on the porous-rich superficial of the catalyst; these covalent C-O-Cu bonds shortened the migration distance of electrons between Cu(II) and Cu(I) via Cu(I)-O-C-O-Cu(II) bridge. The construction of copper-containing covalent bonds in the catalyst resulted in efficient PMS activation for a rapid redox cycle of Cu(II)/Cu(I), triggering a series of reactions involving the continuous production of three highly active species (SO₄^·-, ^·OH and ¹O₂). The rapid diffusion and transportation of the generated active species from porous structures directly attack typical pharmaceutically active compounds (PhACs), achieving superior catalytic performance. This study provides a new routine to construct a C-O-Cu bond for PMS activation by regulating the electron transfer to accelerate the redox behavior of copper species for environmental remediation.

Fabrication of a Novel AgBr/Ag2MoO4@InVO4 Composite with Excellent Visible Light Photocatalytic Property for Antibacterial Use

A novel AgBr/Ag2MoO4@InVO4 composite photocatalyst with different heterojunction structures was successfully constructed by compounding InVO4 with Ag2MoO4 and AgBr. According to the degradation, antibacterial and free radical trapping data, the photocatalytic antibacterial and antifouling activities of AgBr/Ag2MoO4@InVO4 composite were evaluated, and the corresponding photocatalytic reaction mechanism was proposed. Adding AgBr/Ag2MoO4@InVO4 composite, the degradation rate of ciprofloxacin (CIP) achieved 95.5% within 120 min. At the same time, the antibacterial rates of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) achieved 99.99%. The AgBr/Ag2MoO4@InVO4 composite photocatalyst showed promising usage in photocatalytic antibacterial and purification areas.