Search Results (293)

In this study, PTA&PMA/NiMoO₄@NF was synthesized on nickel foam through wet chemical etching to promote the kinetics of the oxygen evolution reaction (OER) effectively. OER benefits from two cationic (Ni and Mo) defects and the optimized electronic configuration of PTA&PMA/NiMoO₄@NF. Thus, it only needs 200 mV to reach the current density of 10 mA cm⁻² in 1.0 mol/L of KOH. This value is nearly 100 mV lower than the value needed by pure NiMoO₄. After being used as an anode for water splitting in an alkaline solution, the as-obtained catalyst can operate at a current density of 10 mA cm⁻² for 24 h of good stability. The synthesis strategy adopted in this study can provide an effective, low-cost, simple, and convenient strategy for improving the OER electrocatalytic performance of other transition metal oxides. Full article

Solid electrolytes, including polymer electrolytes, are a promising option for improving the performance of environmentally friendly batteries such as rechargeable lithium-ion batteries or fuel cells. Hydrogen–oxygen fuel cells producing only water under power generation are attracting widespread attention, and they need proton conductors as electrolytes. Fluoropolymer electrolytes such as Nafion^® have been utilized for hydrogen–oxygen fuel cells below 100 °C; however, they are not applicable over the working temperature. Therefore, other types of polymer electrolytes are demanded for hydrogen–oxygen fuel cells. Polyoxometalate (POM) inorganic clusters are known as proton conductors and are utilized to prepare POM–polymer composites for solid electrolyte application. In such POM–polymer composites, distinct compositions and structures are significant for improving the performance of proton conductivity. Recently, POM–polymer composites with distinct compositions and structures have been synthesized to obtain high proton conductivity. The key factor is to use single-crystalline compounds. Here, several examples are overviewed by classifying them into three categories: (i) single-crystalline POM–polymer composites, (ii) organically modified POM (org-POM) polymers, and (iii) POM hybrid polymers using polymerizable cations. The application of proton-conductive solid electrolytes is focused on. Full article

Redox Flow Batteries (RFBs) are promising large-scale Energy Storage Systems, which support the integration of renewable energies into the current electric grid. Emerging chemistries for electrolytes, such as Polyoxometalates (POMs), are being studied. POMs have attracted great interest because of their reversible multi-electron transfers and the possibility of tuning their electrochemical properties. Recently, the cobalt-containing Keggin-type species [CoW₁₂O₄₀]⁶⁻ (CoW₁₂) has been successfully implemented in a symmetric RFB, and its further implementation calls for new materials for the membrane to enhance its cell performance. In this work, different types of ion exchange membranes (Nafion™-NR212, FAPQ-330 and Amphion™) were tested. The electrolyte uptake, swelling, conductivity and permeability of the membranes in the CoW₁₂ electrolyte, as well as a detailed cell performance study, are reported herein. Better performance results ascribed to the robustness, efficiency and energy density of the system were found for Nafion™-NR212, with 88.5% energy efficiency, 98.9% capacity retention and 3.1 Wh L⁻¹ over 100 cycles at 20 mA cm⁻². FAPQ-330 and Amphion membranes showed large capacity fade (up to 0.2%/cycle). Crossover and the low conductivity of these membranes in the mild pH conditions of the electrolyte were revealed to be responsible for the reduced cell performance. Full article

Background/Objectives: This study examined the fabrication and characterization of nanosponges (NS) laden with polyoxometalates (TiW₁₁Co) with the intention of targeting malignancy. Methods: By employing the emulsion solvent diffusion technique, TiW₁₁Co-NS were generated by combining polyvinyl alcohol (PVA) and ethyl cellulose (EC) in different concentrations. Results: A significant numerical results encompassed a hydrodynamic particle diameter of 109.5 nm, loading efficiencies reaching 85.9%, and zeta potentials varying from −24.91 to −27.08 (mV). Scanning and transmission electron microscopy were employed to validate the TiW₁₁Co-NS porous structure and surface morphology. The results of the stability investigation indicated that TiW₁₁Co-NS exhibited prolonged sturdiness. Investigation examining the inhibition of enzymes revealed that TiW₁₁Co-NS exhibited enhanced effectiveness against TNAP. Pharmacological evaluations of TiW₁₁Co-NS demonstrated improved cytotoxicity and apoptotic effects in comparison to pure TiW₁₁Co, thereby indicating their potential utility in targeted cancer therapy. In vivo investigations involving mice revealed that TiW₁₁Co-NS caused a more substantial reduction in tumor weight and increased survival rates in comparison to pure TiW₁₁Co. The resemblance of TiW₁₁Co for crucial proteins associated with cancer proliferation was featured through molecular docking, thereby supporting its therapeutic potential. Conclusions: The TiW₁₁Co-laden nanosponges demonstrated superior stability, enzyme inhibition, cytotoxicity, and in vivo anticancer efficacy, underscoring their potential for targeted cancer therapy. Full article

Three new inorganic-organic hybrid compounds, (H₃DIBA)₂·SiMo₁₂O₄₀·H₂O (1), (H₃DIBA)₂·SiW₁₂O₄₀·H₂O (2), and [(H₂DIBA)(H₃DIBA)]·PMo₁₂O₄₀·2H₂O (3) (HDIBA = 3,5-di(1H-imidazol-1-yl)benzoic acid) were synthesized by the hydrothermal method. The structures were characterized by single-crystal X-ray diffraction, elemental analysis, powder X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. These three compounds are all 3D supramolecular structures formed by Keggin-type polyoxometalate anions and HDIBA through intermolecular weak interactions, which have been studied via Hirshfeld surface analysis. The electrochemistry properties of 1 and 3 have been studied, including cyclic voltammetric behaviors and electrocatalytic properties. The study on the removal of organic dye pollutants in water showed that compounds 1 and 3 had an adsorption effect on cationic dye RhB, and the adsorption process conforms to the Langmuir isotherm model. Compound 2 can photocatalytically degrade cationic organic dyes RhB, MB, and CV, and the photocatalytic mechanism study indicates that h⁺ plays a major role in the photocatalytic process. Full article

Modern research technology’s goal is to produce multifunctional materials that require low energy. In this work, we have applied polypyrrole (PPy) doped with dodecyl benzenesulfonate (DBS-) with the addition of polyoxometalates (POM) such as phosphotungstic acid (PTA) forming PPyDBS-PT composites. Two different PTA concentrations (4 mM and 8 mM) were used to form PPyDBS-PT4 and PPyDBS-PT8. The higher concentration of PTA created a highly dense and compact film which can be observed from scanning electron microscopy (SEM cross-section image), and also contains fewer phosphotungstate anions (PT³⁻) inclusion (via energy-dispersive X-ray spectroscopy, EDX). Three different aqueous electrolytes, LiCl (lithium chloride), NaCl (sodium chloride), and KCl (potassium chloride), were applied to investigate how those alkali metal ions perform as typical cation-driven actuators. Cyclic voltammetry with linear actuation revealed the tendency LiCl > NaCl > KCl in view of better strain, charge density, electronic conductivity, and Young’s modulus of PPyDBS-PT4 outperformed PPyDBS-PT8. Chronopotentiometric measurements showed high specific capacitance for PPyDBS-PT4 at 260.6 ± 21 F g⁻¹ with capacity retention after 5000 cycles of 88.5%. The sensor calibration of PPyDBS-PT4 revealed that the alkali cations (Li⁺, Na⁺, and K⁺) can be differentiated from each other. The PPyDBS-PT4 has multifunctional applications such as actuators, sensors, and energy storage. Full article

The efficient removal of dyes and Cr(VI) from wastewater is imperative. Therefore, a mixed metal oxide CuMoV(450) derived from a polyoxometalate-based metal–organic framework (POMOF) [Cu(2,2′-bipy)][Cu(2,2′-bipy)₂]₂[PMo₈V₆O₄₂]•2H₂O (CuMoV) was synthesized by calcination, fully characterized by XRD, XPS, FT-IR, and SEM methods, and explored for the heterogeneous catalytic degradation of methylene blue (MB) dye and the catalytic reduction of Cr(VI) in aqueous media over NaBH₄ under mild conditions. The removal rates for MB and Cr(VI) were 95.9% (30 min) and 96.5% (2.0 min), respectively. The pseudo-first-order rate constants of MB degradation and Cr(VI) reduction were 0.093 min⁻¹ and 1.536 min⁻¹, respectively. The highly catalytic reusability of CuMoV(450) was confirmed by the recycling experiments. Moreover, the possible mechanisms of MB degradation and Cr(VI) reduction were proposed. The catalytic activities of CuMoV(450) were much better than those of its parent compound CuMoV, proving that POMOFs were good candidates for the preparation of mixed metal oxides with excellent catalytic performances. This work not only indicates that CuMoV(450) has the potential to be a satisfied catalyst for wastewater remediation via catalytic degradation and reduction, but also gives a clue to synthesize mixed metal oxides with excellent catalytic properties by the calcination of POMOFs. Full article

The efficient utilization of lignin, a pivotal component of lignocellulosic biomass, is crucial for advancing sustainable biorefinery processes. However, optimizing lignin valorization remains challenging due to its intricate structure and susceptibility to undesirable reactions during processing. In this study, we delve into the impact of various pretreatment agents on birch lignin, aiming to enhance its catalytic oxidation and depolymerization under polyoxometalates (POMs) catalysis. Our results reveal that pretreatment with formaldehyde effectively safeguards aryl ether linkages in lignin, leading to a notable increase in aromatic compound yields under POMs catalysis. Furthermore, gel permeation chromatography (GPC) analysis underscores the inhibition of aryl ether linkage hydrolysis upon formaldehyde addition. Gas chromatography–mass spectrometry (GC–MS) analysis demonstrates that formaldehyde pretreatment boosts lignin monomer yield by 2 to 3 times compared to untreated lignin, underscoring the effectiveness of tailored pretreatment strategies. This research underscores the significance of adopting rational pretreatment methods to advance lignin valorization pathways catalyzed by POMs, thereby contributing to the evolution of sustainable biomass conversion technologies. Full article

The photoreduction method was utilized to synthesize the Ag/PW₁₂/g-C₃N₄ nanocomposite. The polyanion PW₁₂O₄₀³⁻ served as the photoreductant, and as a stabilizer and protectant for Ag nanoparticles. TEM images reveals that Ag nanoparticles with a size of approximately 5 nm were modified on the surface of g-C₃N₄. Photocatalytic experiments confirm that Ag/PW₁₂/g-C₃N₄, with the mass ratio of Ag₃PW₁₂O₄₀ to g-C₃N₄ nanosheets at 30%, exhibits high efficiency and durability in the photodegradation of Rhodamine B. Research on the photocatalytic mechanism indicates that decorating PW₁₂O₄₀³⁻ and Ag nanoparticles on the surface of g-C₃N₄ nanosheets is beneficial for improving the separation of electron–hole pairs and enhancing the capability for visible light absorption. Full article

With the increasing demand for eco-friendly water treatment solutions, the development of novel photocatalysts such as calcium polyanion (Ca-POM) plays a vital role in mitigating industrial wastewater pollution. In this research, calcium polyanion, H₆₀N₆Na₂Ca₂W₁₂O₆₀ (Ca–POM), was successfully synthesized via a self-assembly reaction from metal-oxide subunits. The synthesized Ca–POM was verified to have a polycrystalline structure with a broad size distribution, with an average particle diameter of approximately 623.62 nm. Powder X-ray diffraction (XRD) analysis confirmed the polycrystalline structure of the Ca–POM, with a calculated band gap energy of 3.29 eV. The photocatalytic behavior of the Ca-POM sample was tested with two model dyes, methylene blue (MB) and methyl orange (MO). The reaction mixture was then exposed to ultraviolet (UV) irradiation for durations ranging from 20 to 140 min. The synthesized cluster demonstrated photocatalytic efficiency (PCE%) values of 81.21% for MB and 25.80% for MO. This work offers a valuable basis for applying Ca–POM as a heterogeneous photocatalyst for treating industrial wastewater organic pollutants and highlights the potential of Ca–POM in sustainable water treatment applications. Full article

The efficient detection of volatile organic compounds (VOCs) is critically important in the domains of environmental protection, healthcare, and industrial safety. The development of metal oxide semiconductor (MOS) heterojunction gas-sensing materials is considered one of the most effective strategies to enhance sensor performance. This review summarizes and discusses the types of heterojunctions and their working principles, enhancement strategies, preparation methodologies, and applications in acetone and ethanol detection. To address the constraints pertaining to low sensitivity, sluggish response/recovery times, and elevated operating temperatures that are inherent in VOC sensors, several improvement methods are proposed, including doping with metals like Ag and Pd, incorporating additives such as MXene and polyoxometalates, optimizing morphologies through a fine design, and self-doping via oxygen vacancies. Furthermore, this work provides insights into the challenges faced by MOSs heterojunction-based gas sensors and outlines future research directions in this field. This review will contribute to foundational theories to overcome existing bottlenecks in MOS heterojunction technology while promoting its large-scale application in disease screening or agricultural food quality assessments. Full article

A series of commercial silica-supported polyoxometalate ionic liquids ([C_nmim]₃PMo₁₂O₄₀) with different substitutes in the imidazole ring were prepared via a facile ball milling method and employed as catalysts in the oxidative desulfurization of organosulfur compounds. The experimental results demonstrated that the active polyoxometalate center was successfully immobilized with a highly uniform dispersion on the silica. Without any organic solvent as the extractant, sulfur removal with the sample C₁₆PMo/SiO₂-BM reached 99.5% in 30 min under the optimal condition, which was ascribed to the high specific surface area and lipophilicity. In addition, the active site was verified by a free radical trapping experiment and an ESR spin capture experiment. In addition, the oxidative product was confirmed by GC-MS analysis. Full article

A d¹⁰-Cd cluster containing sandwich-type arsenotungstate [C₃H₁₂N₂]₆[Cd₄Cl₂(B-α-AsW₉O₃₄)₂] was synthesized and its structure characterized through elemental analyses, X-ray powder diffraction (XRPD), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and single-crystal X-ray diffraction. The X-ray analysis revealed that the molecular unit of the compound consists of a captivating tetra-Cd-substituted sandwich-type polyoxoanion, accompanied by six elegantly protonated 1,2-diaminopropane as counter ions. The further novelty of the tetranuclear cadmium cluster lies in its occupied chlorine atom sites. This makes it highly susceptible to coordinate reactions with nitrogen on polycyclic aromatic hydrocarbons, thereby exhibiting different fluorescent signals that facilitate the identification and detection of these carcinogenic substances in methanol. Full article

Reticular and cluster materials often feature complex formulas, making a comprehensive overview challenging due to the need to consult various resources. While datasets have been collected for metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and zeolites, among others, there remains a gap in systematically organized information for polyoxometalates. This paper introduces a carefully curated dataset of 1984 polyoxometalate (POM) and related cluster metal oxide formula instances, currently connecting over 2500 POM material instances. These POM instances incorporate 75 different chemical elements, with compositions ranging from binary to octonary element clusters. This dataset not only enhances accessibility to polyoxometalate data but also aims to facilitate further research and development in the study of these complex inorganic compounds. Full article