Binary Metal Oxides Research Articles

Research Progress in the Composition and Performance of Mn-Based Low-Temperature Selective Catalytic Reduction Catalysts

NH3 selective catalytic reduction (NH3-SCR) is the most prevalent and effective method for removing nitrogen oxides. Over the past few decades, manganese (Mn)-based catalysts have demonstrated strong catalytic activity and have been extensively studied for low-temperature NH3-SCR reactions. This paper provides an in-depth introduction to four forms of Mn-based catalysts: single manganese oxide-based catalysts, binary Mn-based metal oxide catalysts, ternary and multivariate Mn-based metal oxide catalysts, and nano-Mn-based catalysts. Advances have been made in enhancing Mn-based catalysts’ redox performance and acidity, increasing the active component’s dispersion, lowering binding energy, enlarging specific surface area, raising the Mn4+/Mn3+ ratio, and enriching surface adsorbed oxygen by optimizing preparation methods, altering the oxidation state of active components, modifying crystal phases, and adjusting morphology and dispersion, along with various metal modifications. The mechanism of low-temperature NH3-SCR reactions has been elucidated using various characterization techniques. Finally, the research directions and future prospects of Mn-based catalysts for low-temperature NH3-SCR reactions are discussed, aiming to accelerate the commercial application of new Mn-based catalysts.

One-Step Fabrication of 2.5D CuMoOx Interdigital Microelectrodes Using Numerically Controlled Electric Discharge Machining for Coplanar Micro-Supercapacitors

With the increasing market demands for wearable and portable electronic devices, binary metal oxides (BMOs) with a remarkable capacity and good structure stability have been considered as a promising candidate for fabricating coplanar micro-supercapacitors (CMSCs), serving as the power source. However, the current fabrication methods for BMO microelectrodes are complex, which greatly hinder their further development and application in BMO CMSCs. Herein, the one-step fabrication of 2.5D CuMoOx-based CMSCs (CuMoCMSCs) has been realized by numerically controlled electric discharge machining (NCEDM) for the first time. In addition, the controllable capacity of CuMoCMSCs has been achieved by adjusting the NCEDM-machining voltage. The CuMoCMSCs machined by a machining voltage of 60 V (CuMoCMSCs60) showed the best performance. The fabricated CuMoCMSCs60 with binary metal oxides could operate at an ultra-high scanning rate of 10 V s−1, and gained a capacity of 40.3 mF cm−2 (1.1 mA cm−2), which is more than 4 times higher than that of MoOx-based CMSCs (MoCMSCs60) with a single metal oxide. This is because CuMoOx BMOs materials overcome the poor electroconductivity problem of the MoOx single metal oxide. This one-step and numerically controlled fabrication technique developed in this research opens a new vision for preparing BMO materials, BMO microelectrodes, and BMO microdevices in an environmental, automatic, and intelligent way.

The Elevated Temperature Tribological Performance of Tough and Superhard TaMoN-Ag films with Solute and Nanocomposite Structures

Abstract Films have been prepared with not only high hardness to guarantee excellent wear resistance but also high toughness to prevent brittle fracture at low to middle-high temperatures. On the basis of ternary transition metal nitrides with significantly improved hardness and toughness, TaMoN-Ag films with solute and nanocomposite structure were prepared by DC magnetron sputtering technology. Friction wear tests were performed between room temperature (RT) and 700 °C. When doping with trace amounts of Ag atoms (∼1.12 at.%, 4 W), TaMoN-Ag films maintain solid solution structure. TaMoN-Ag films with the Ag target power is 4 W show the highest hardness (H∼62.1 GPa), which is 58% higher than TaMoN film and 44% better than that of TaMoN films. Meanwhile, a lower wear rate (KIC∼5.87×10-7 mm3/N·m) is obtained. The tribological properties of TaMoN-Ag films at room temperatures are related to the H3/E2 and lubricious Ag phase, while the tribological properties at high temperatures are mainly due to the formation of lubricating binary metal oxides (AgxTMyOz (Magnéli phases)). The composite films generally have good resistance to plastic deformation.

An Efficient Approach for Advancing Performance in Rapid Detection Based on Molybdenum Disulfide Nanoflower Supported Binary Transition Metal Oxides.

Binary transition metal oxides (BTMOs) have drawn considerable attention in recent years for their excellent catalytic properties and chemical stability in the sensing field. Regrettably, the loss of active site exposure originating from the agglomerate during preparation largely restricted their sensing applications. In this work, we report an efficient strategy for advancing the performance of BTMOs in rapid detection based on a 3D molybdenum disulfide nanoflower. The larger surface area, multiple active site exposures, and higher electrical conductivity promote the dispersion of BTMOs and the redox reaction of analytes on the surface of nanocomposites, thereby enhancing the sensitivity and widening the quantitative range. As a proof-of-method application, ferric vanadate (FeVO4) and ciprofloxacin (CIP) were chosen as model catalysts and analytes, respectively. This approach exhibits excellent sensitivity, selectivity, repeatability, and stability. The detection limit could be as low as 26.6 nM, and the linear range covered 3 orders of magnitude (from 0.1 to 500 μM). It also demonstrated good practicality in milk, honey, and drinking water with a recovery of 90.6% to 100.8%. To our knowledge, this is the first report on incorporating MoS2 into BTMOs for augmenting sensing performance in rapid detection.

A Lean Six Sigma approach aided improvement for simultaneous electrochemical determination of antiviral drug favipiravir and levodropropizine as an option in the treatment of COVID-19 using glassy carbon electrode modified NiFe2O4 nanocomposite in different matrices

Favipiravir (FPV) is a widely used drug that works well against a variety of infectious RNA viruses. It is commonly used as an anti-influenza medication. To treat patients infected with RNA viruses, combination therapy consisting of FPV and levodropropizine (LDP) is required. As a result, an effective electrochemical sensor for identifying FPV in human plasma samples has been developed. The hydrothermal method is used to synthesize NiFe2O4NPs, a binary transition metal oxide comprising iron and nickel. The effective synthesis of these materials is verified by energy-dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). The developed nanocomposite underwent physicochemical and electrochemical characterization, and the experimental setup was refined. Two broad linear dynamic ranges were obtained for both medications using Differential Pulse Voltammetry (DPV): 0.5 µM–200 µM for FPV and 1.0 µM–110 µM for LDP. For FPV, the computed detection and quantitation limits were 0.148 µM and 0.45 µM, while for LDP, they were 0.297 µM and 0.9 µM. The recommended technique was successfully used to analyze both medications at the same time in human plasma samples, and acceptable percentage recoveries were attained. In terms of greenness, EcoScale and GAPI greenness tools were used to evaluate the analytical methodology. Additional studies on repeatability, stability testing, interference analysis, and greenness evaluation supported the validity of the recommended method for the simultaneous measurement of FPV and LDP in laboratories for quality assurance. Additionally, Lean Six Sigma (LSS) quality technique is regarded as a collection of management disciplines for continuous improvement and method control. It is thought to offer the most practical way to address the negative effects of variation by taking steps toward analytical process improvement. As a result, LSS can be considered an invaluable tool in any laboratory, serving as a standard method for process optimization and problem solutions as well as a managerial discipline. Furthermore, it guarantees a strong method specification at a high degree of statistical confidence and targeted performance.

New Suggestion of Highly Durable Electrode Design for Ordered Mesoporous Ni-Mn Binary Transition Metal Oxide Anode Material in Lithium-Ion Batteries.

Anode materials storing large-scale lithium ions gradually decrease electrochemical performance due to severe volume changes during cycling. Therefore, there is an urgent need to develop anode materials with high electrochemical capacity and durability, without deterioration arising due to the volume changes during the electrochemical processes. To date, mesoporous materials have received attention as anode materials due to their ability to mitigate volume expansion, offer a short pathway for Li+ transport, and exhibit anomalous high capacity. However, the nano-frameworks of transition metal oxide collapse during conversion reactions, demanding an improvement in nano-framework structure stability. In this study, ordered mesoporous nickel manganese oxide (m-NMO) is designed as an anode material with a highly durable nanostructure. Interestingly, m-NMO showed better cycle performance and higher electrochemical capacity than those of nickel oxide and manganese oxide. Operando small-angle X-ray scattering and ex situ transmission electron microscopic results confirmed that the binary m-NMO sustained a highly durable nanostructure upon cycling, unlike the single metal oxide electrodes where the mesostructures collapsed. Ex situ X-ray absorption spectroscopy proved that nickel and manganese showed different electrochemical reaction voltages, and thus undergoes sequential conversion reactions. As a result, both elements can act as complementary nano-propping buffers to maintain stable mesostructure.

Pt-decorated binary transition metal oxides (MnO-NiO, MnO-TiO2) for enhanced electrocatalysis of oxygen reduction and borohydride oxidation

Integrating transition metal oxides with precious metals is a strategic approach to designing cost-effective electrocatalysts with enhanced stability. Herein, platinum (Pt) nanoparticles (NPs) were prepared by microwave irradiation and anchored onto MnO and two binary metal oxides, MnO-NiO and MnO-TiO2, obtained by solid-state dispersion. Voltammetric and electrochemical impedance spectroscopy techniques evaluated their performance for oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) in alkaline media. Tafel slope and the number of exchanged electrons, n, were determined to compare the three electrocatalysts’ performance for fuel cell applications. Pt/MnO-NiO revealed a Tafel slope of 177 mV dec–1 for ORR and an n value of ca. 4 and 3 e- for ORR and BOR, respectively. These findings demonstrate that Pt NPs supported on binary metal oxide supports, particularly Pt/MnO-NiO, are promising electrocatalysts for ORR and BOR in alkaline media, thus recommending their use in direct borohydride fuel cells.

Molten salt electrolytic CO2-derived NiCo2@C catalysts with enhanced oxygen evolution reaction

Carbon-based nonprecious metallic electrocatalysts have garnered considerable attention due to their tunable structures, rapid electron transfer, and easy characterization. There is great anticipation for the development of green and controllable methods for metal-carbon-based electrocatalysts. Molten salts synthesis offers a green, facile and effective approach for fabricating carbon-based materials, utilizing carbon dioxide (CO2) as the carbon source. In this study, the co-electroreduction of CO2 and the binary metal oxide NiCo2O4 is carried out in a mixture of Li2CO3, Na2CO3, and K2CO3 at 500oC. This process leads to the formation of metal alloy nanoparticles encapsulated in a carbon matrix derived from CO2, referred to as NiCo2@C. The resulting NiCo2@C exhibits low overpotential and Tafel slope (340mV@10mAcm−2, 67mV dec−1) in 0.1M KOH solution for OER, which is superior to the commercial RuO2 (360mV@10mAcm−2, 88mV dec−1). Both experimental and theoretical findings indicate the synergistic effects of Ni/Co bimetallic sites. Spontaneous adsorption of hydroxide ion on the bridging sites of heterologous diatoms facilitates the adsorption and desorption of intermediates during the OER process.

Bioflocculant polymer reduced CuO/NiO binary transition metal oxide nanocomposite: Application as an effective non-enzymatic glucose sensor

A bimetallic copper oxide/nickel oxide nanocomposite (CuO/NiO NCs) was synthesized via direct carbonization method by using microbial polymer as reducing agent. This nanocomposite was employed as a viable non-enzymatic electrocatalyst in the glucose detection. It was completely characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopic (EDX) methods and revealed the obtained porous nanoflower morphology with particle sizes of 100–200 nm in a monoclinic face-centered cubic crystalline structure. FT-IR spectra confirmed the presence of functional groups and the purity of the nanocomposite. Electrocatalytic performance for glucose oxidation was evaluated through cyclic voltammetric (CV) and amperometric i-t techniques. The observation demonstrated that the CuO/NiO NCs exhibited a remarkable electro-oxidation activity against glucose, attributed to the synergistic effects of the bimetallic components. As an electrode surface modifier, the CuO/NiO NCs facilitated an enhanced glucose oxidation over a linear range of 1–9 mM via CV, while amperometric i-t measurements achieved a detection range from 0.04 μM to 4.86 mM in a 0.1 M NaOH (pH ∼ 13) electrolyte solution. These eco-friendly and in-expensive nanoflowers displayed excellent selectivity, stability, and reproducibility, underscoring their potential in diabetes monitoring and the subsequent scientific analysis.

Data-driven catalyst design for oxidative dehydrogenation of propane with CO2 using decision tree regression

Interpretable machine learning (ML) techniques have made significant progress in the design of high-performance materials. Here we employ decision tree (DT) models to discover and optimize multicomponent catalysts for the oxidative dehydrogenation of propane with CO2 (ODPC). While DT models have been used to improve a single target variable, this study leverages interpretable models by simultaneously considering the criteria for improving all the multiple target variables of ODPC, namely C3H8 conversion, CO2 conversion, and C3H6 yield. Instead of using literature data, we establish a consistent laboratory-scale database, and DT models are trained on multiple target variables representing catalytic performance. The trained DT models identify key input variables, including active metals, compositions, and support materials and provide criteria in the form of inequalities for the design of new ODPC catalysts. Despite using a database of binary and ternary metal oxides only, the fulfilment of all criteria suggests quaternary metal oxides with Cr, Ni, Mo, and ZrOx. The DT-proposed multicomponent catalysts show superior ODPC performance to the database catalysts, with a synergistic effect between the active elements. This exploitation of the relationship information between catalyst components and performance highlights the benefit of interpretable ML techniques in the design of high-performance multicomponent catalysts.

Dual polarization in CoMoO4-NiMoO4 heterojunction boosted electrochemical charge storage

Binary transition metal oxides (BTMOs) stand out as a focal point due to their distinctive electrochemical properties. However, they encounter challenges like low conductivity and limited active sites. To tackle these obstacles, we have meticulously designed a CoMoO4-NiMoO4 (CMNM) heterostructure featuring significant compressive-tensile strain. This design facilitates the robust integration of CoMoO4 (CM) and NiMoO4 (NM), initiating interfacial polarization, and establishing a built-in electric field (BIEF) that significantly enhances electron transfer between the phases. Moreover, the strain serves as a driving force for the electric field, promoting the rearrangement of interface electrons and further boosting interfacial polarization. This avant-garde approach propels the CMNM electrode to achieve a remarkable specific capacity of 530.45 C g−1 at 1 A g−1, maintaining 327 C g−1 even at 10 A g−1, thus showcasing a superior rate capability. Furthermore, an asymmetric supercapacitor employing CMNM as the positive and FeOOH as the negative achieves a high energy density of 78.9 Wh kg−1 at a power density of 927.02 W kg−1. Our methodology, leveraging heterostructures coupled with the interfacial strain tactics, paves a novel avenue for high-performance supercapacitors.

Ultra-small one-dimensional rice-like CoMoO4 nanorods as a promising pseudocapacitive electrode for high-performance supercapacitors

The demand for sustainable energy sources increases as society progresses. Supercapacitors possess a long lifespan, have a high power density, are ecologically sound, and have the ability to rapidly charge and discharge. Among the several binary transition metal oxides (BTMOs), metal molybdates (AMoO4) are notable for their significant redox activity, widespread availability, affordability, and small ecological footprint. The exceptional theoretical capacitance of CoMoO4, resulting from the presence of active cobalt ions, distinguishes it from other materials. However, the synthesis of CoMoO4 in nanostructured forms presents a challenge. This study introduces a straightforward one-pot solvothermal technique for producing ultra-small, one-dimensional (1D) rice-like CoMoO4 nanorods. The electrochemical performance of rice-like CoMoO4 nanorods as a supercapacitor electrode material was thoroughly investigated, along with larger CoMoO4 nanorods made using the hydrothermal process for comparison. The structural, morphological, and surface characteristics of the rice-like CoMoO4 nanorods were comprehensively examined. The nanorods, formed like rice grains, exhibited exceptional ability to store electric charge, with an outstanding specific capacitance of 1608.8 F g−1. They demonstrated remarkable cycling stability, retaining 96 % of their capacitance after numerous charge and discharge cycles, indicating their durability and reliability. The nanorods also exhibited a high rate capability of 71 %, which is crucial for applications that demand quick energy delivery. This capability enables the nanorods to maintain considerable capacitance even at higher charge-discharge rates. The results indicate that rice-like CoMoO4 nanorods can be used as a material in supercapacitors.

Facile construction of binary metal oxide heterojunction with hexagonal boron nitride nanohybrid electrocatalyst for the detection of flutamide

BackgroundFlutamide (FU) is a potential anti-androgen drug significantly prescribed to all human beings. The high solubility and poor degradability of its metabolites can adversely affect the balance of the ecosystem. Therefore, developing an efficient and reliable technique to detect this pollutant is essential. Consequently, electrochemical sensors have been widely used for the monitoring of various real-world samples. MethodsHence, nickel-zinc oxide (NZO) with hexagonal boron nitride (h-BN) nanocomposite was prepared as a proficient electrocatalyst in FU detection. Several spectroscopic measurements were carried out to characterize the prepared materials. Our NZO/h-BN nanocomposite was utilized to modify the glassy carbon electrode (GCE) and its relative catalytic activity was scrutinized with impedance and various voltammetric techniques. Significant findingsBased on the results, our NZO/h-BN/GCE sensor exhibited high conductance, appreciable linear ranges, low detection limit (0.002 μM), optimal sensitivity (2.149 µA µM−1 cm−2), and high selectivity with good repeatability, and reproducibility results. Furthermore, the practical utility of the sensor was studied by monitoring FU in human and environmental samples. Based on the outcomes, our NZO/h-BN/GCE is a promising electrochemical platform for the detection of FU.

Using Nanoscale Metal Oxide Films to Investigate the Influence of Anode Interfaces on Lithium Battery Performance

As renewable energy and battery-powered technologies become more widespread, high energy-density and high-performing batteries are required to meet society’s needs. While lithium-ion batteries have been the staple, their energy density development has been slow, and at gravimetric energy densities of around 250 Wh/kg, they are approaching their theoretical limit.1 The lithium-metal battery (LMB) is considered a next-generation battery due to high theoretical energy densities (ex: Lithium-Sulfur, 2600 Wh/kg), and lithium metal’s high gravimetric capacity (3860 mAh/g) and low reduction potential (-3.04 V vs S.H.E.). However, commercialization of LMBs has been limited due to various issues.Two properties that dictate the performance of the LMBs are: 1. The composition of the solid electrolyte interphase (SEI), an electronically conducting, yet passivating, layer at the anode-electrolyte interface, and 2. The morphology of the lithium deposited at the anode. Morphological studies focus on creating dense, low surface area, deposits that limit SEI fracturing and the formation of electronically disconnected lithium. SEI quality is improved by incorporating inorganic or anion-rich SEIs, formed from the electrolyte salt, to promote SEIs that are mechanically robust, ionically conducting, and homogeneous. Our group’s previous work aimed to improve LMB performance via both routes by growing resistive Al2O3 coatings on the copper (Cu) current collector using atomic layer deposition (ALD). Defects in the thin film create areas of low resistance that behave like ultramicroelectrodes which encourage radial diffusion of lithium ions to the nuclei promoting lateral growth and producing low surface area, dense, planar lithium deposits. Simultaneously, the Al2O3 coating’s Lewis acidic properties promote the decomposition and subsequent incorporation of inorganic electrolyte species into the SEI.We present a study of how the different interfaces present at the anode in LMBs impact SEI composition and battery performance. To hold the Li nucleation morphology at the anode constant, we deposit metal oxide films of a fixed resistance onto the Cu current collector, generating planar, low surface area, lithium deposits. This experimental design allows us to decouple the effect of the metal oxide thin film-electrolyte interface on SEI quality and battery performance from that of the lithium morphology. First, as shown in Fig. 1a, different metal oxide films of equal resistance, but different thicknesses, are grown via ALD, confirmed by measuring the first-cycle nucleation overpotential. The resistive metal oxides investigated are Al2O3, HfO2, AlHfxOy, and ZrO2. Scanning electron microscopy results indicate that all cells modified with equal resistance metal oxide films exhibit the same low surface area, dense, planar Li nucleation morphology. However, long-term cycling tests show differences in cell performance and life cycle. Subsequently, the composition of the SEI is investigated using X-ray photoelectron spectroscopy (XPS). Through XPS, an elemental atomic ratio analysis is conducted to investigate the relative number of species derived from the anion of the electrolyte versus the solvent of the electrolyte to reflect the anion-derived nature of the SEI. Additionally, high-resolution peaks are used to determine the relative abundance of high-quality SEI species such as lithium fluoride. This analysis confirms that the metal oxide thin film tunes the SEI composition. Additionally, we identify trends present between the SEI quality of the ALD-modified cell and its performance.To further investigate the thin film-electrolyte interface, a set of cells modified with binary stacked metal oxide thin films with two different stack orders were created, as shown in Fig. 1b. Investigating SEI composition and LMB performance, with the morphology fixed by the nucleation overpotential, allowed for deconvolution of the impact of the Cu-thin film interface and thin film-electrolyte interface. Both interfaces can in principle impact the battery’s function because 1. The Cu-thin film interface controls the electron transport to form Lio from Li+ ion during electrodeposition, and 2. The thin film-electrolyte interface can modulate the SEI. Our results indicated that the SEI and performance were both primarily regulated by the thin film-electrolyte interface. Based on our fixed-resistance and binary stack experimental design, we propose that modulation of the SEI composition by the metal oxide coating controls LMB performance when the Li nucleation morphology is fixed. This result suggests the potential for tuning LMB performance by careful selection of the metal oxide interfacial coating. References (1) Cheng, X.-B., et al. Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review. Chem. Rev. 2017, 117 (15), 10403–10473. https://doi.org/10.1021/acs.chemrev.7b00115.(2) Oyakhire, S. T., et al. Electrical Resistance of the Current Collector Controls Lithium Morphology. Nature Communications 2022, 13 (1), 3986. https://doi.org/10.1038/s41467-022-31507-w. Figure 1

Earth-Abundant Metal Oxides as Oxygen Evolution Electrocatalysts in 1 M H2SO4

Water splitting is a very hot research topic as a preferred source for green hydrogen, as a key vector to facilitate a transition into an environmentally friendly and sustainable energy economy in the mid-term. But it is still far from being economically competitive with respect to current hydrogen production technologies based on fossil fuels. One of the major economic hurdles to reduce electrolysis costs is the lack of low-cost catalysts for hydrogen evolution and, more importantly, for oxygen evolution. The water oxidation process is considered the main bottleneck in the advancement of water splitting devices, since it is the rate limiting process, and the main cause of poor long-term performance.Most recent advances in the field of water oxidation catalysis are based on transition metal oxides, operating exclusively in alkaline electrolysis conditions. Unfortunately, these excellent oxygen evolution catalysts in basic pH ( > 13) rapidly lose their activity when the pH is lowered, and are far away from the performance exhibited by noble metals in acid solution. McCrory et al. established in 2013 1a benchmarking protocol to identify the potential of new OER electrocatalysts (and extended in 2015 2 to HER) comparing the initial activity and stability of the materials as a function of pH and showed how no other known catalysts at that time came close to the performance of IrOx-based materials.A simple processing technique using a partially hydrophobic binder has been proved to stabilize Co oxide, resulting in electrodes able to reach high current densities (> 10 mA cm-2) at competitive overpotentials and with long term stability for acidic OER catalysis3. Following this strategy, we have been able to conduct an extensive survey of the activity and stability of monometallic, binary and ternary earth-abundant transition metal oxides during electrocatalytic OER in 1 M H2SO4. Our results confirm the general validity of the strategy in using a partially hydrophobic electrode to confer high stability to common metal oxides under these harsh conditions.[1] C.C.L. McCrory, S. Jung, J.C. Peters, T.F. Jaramillo, Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction, J. Am. Chem. Soc. 135 (2013) 16977–16987.[2] C.C.L. McCrory, S. Jung, I.M. Ferrer, S.M. Chatman, J.C. Peters, T.F. Jaramillo, Benchmarking Hydrogen Evolving Reaction and Oxygen Evolving Reaction Electrocatalysts for Solar Water Splitting Devices, J. Am. Chem. Soc. 137 (2015) 4347–4357.[3] J. Yu, F.A. Garcés-Pineda, J. González-Cobos, M. Peña-Díaz, C. Rogero, S. Giménez, M.C. Spadaro, J. Arbiol, S. Barja, J.R. Galán-Mascarós, Sustainable oxygen evolution electrocatalysis in aqueous 1 M H2SO4 with earth abundant nanostructured Co3O4, Nat. Commun. 13 (2022) 4341. Figure 1

Electrocatalytic Conversion of CH4 to High Value-Added Liquid Fuel over Binary Metal Oxide Tandem Catalysts

As the main component (> 85%) of combustible ice and shale gas, methane (CH4), plays a significant role in the greenhouse effect.(1) Although CH4 was widely used to synthesize high value-added Cx oxygenates via indirect industrial reforming with high-energy consumption. The accurate control of oxidation degree in CH4 conversion remains a great challenge.(2) Therefore, it is difficult to achieve high conversion rate and high selectivity at the same time. The convenience and reliability of the control of reaction potential, as one of the advantages of electrocatalysis technology, can effectively address the above problems.(1, 3) Electrochemical technologies of CH4-to-Cx oxygenates are regarded as one of the most attractive pathways to produce bulk industrial liquid fuels.(4) Especially in the premise of clean energy as an energy source, the electrochemical conversion of methane demonstrates very advantageous market potential. In this work, we prepared a ZrO2 modified FeOx binary metal oxides tandem catalyst to accelerate partial oxidation of CH4 under ambient condition. With CO3 2- as an oxidant, ZrO2@FeOx tandem catalyst shows remarkable CH4 conversion performance with large current density gap (13.65 mA cm-2) and long-term electrochemical stability (negligible attenuation (8 %) after 48 hours) in three-electrodes cell. In addition, in a flow reactor, ZrO2@FeOx-based electrode also exhibits a highly stable operating lifespan over 72 hours at a large current density 50 mA cm-2 and achieve a feasible CH4-liqid fuel conversion with high total faradaic efficiency.References F. Liu, Y. Yan, G. Chen and D. Wang, Green Chemistry, 26, 655 (2024).S. Yuan, Y. Li, J. Peng, Y. M. Questell-Santiago, K. Akkiraju, L. Giordano, D. J. Zheng, S. Bagi, Y. Román-Leshkov and Y. Shao-Horn, Advanced Energy Materials, 10, 2002154 (2020).M. R. A. Kishore, S. Lee and J. S. Yoo, Adv Sci (Weinh), 10, e2301912 (2023).L. Fu, R. Zhang, J. Yang, J. Shi, H. Y. Jiang and J. Tang, Advanced Energy Materials, 13 (2023).

Eley−Rideal path enhanced NH3-SCR: Central Fe atoms activation for electron transfer promotion

Manganese modified Fe2O3 catalyst is a promising candidate to replace the commercial NH3-SCR catalyst for controlling NOx emission due to its superior performance and N2 selectivity at low temperature. In order to elucidate the effects of different modification methods of Mn on physicochemical properties and reaction mechanism in Fe-Mn binary catalysts, two kinds of Mn modified Fe2O3 are prepared by co-precipitation and impregnation method, respectively. Compared with MnO2 loaded Fe2O3, Mn doped Fe2O3 achieves above 85 % of NOx conversion with 20 % increase in N2 selectivity within 100–200°C. Transient reaction experiments and DFT calculation results prove that doping Mn effectively increases the reaction rate of the main reaction and reduces the formation of N2O through Eley−Rideal path. The formation of multiple Fe-O-Mn structures after Mn doping facilities the formation of coordination bond between the central Fe atoms and NH3 via modulating local charge density of Fe atoms, effectively improving the adsorption of NH3 and preventing its excessive oxidation, which leads to high activity and N2 selectivity at low temperature. This mechanism provides theoretical support for increasing the activity and N2 selectivity of NH3-SCR catalysts at low temperature and gains clear insight on the interaction between binary metal oxides.

Alkaline metal tungstate anchored on functionalized-MWCNT: A co-active electrocatalyst for the detection of levofloxacin

The widespread usage of levofloxacin (LVF) intake is executed for several urinary and respiratory systems infections in human. But, its over intake leads to severe damage to humans and the environment by its exposure. Hence the detection of LVF is concerned and we herein developed an electrocatalyst, strontium tungsten oxide nanospheres and later decorated onto the functionalized multiwall carbon nanotubes (SrWO4/f-MWCNT) to perform effective electrochemical recognition of LVF in aquatic and biological samples. Binary metal oxide with carbon composite SrWO4/f-MWCNT was developed due to its specific features as nanostructures. Various methods of investigation have been examined to identify the physiochemical characteristics like X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and morphological characteristics including field emission scanning electron microscopy, and transmission electron microscopy. The synthesized SrWO4/f-MWCNT sample crystalline size was around 32.9 nm. The SrWO4/f-MWCNT modified glassy carbon electrode (GCE) has been subjected to electrochemical investigation with a wide linear range of 0.049 μM–574.73 μM with good sensitivity 2.86 μA μM−1 cm2, the limit of detection at 14.9 nM for LVF sensing. Furthermore, the designed LVF detection exhibited excellent anti-interference, stability, reproducibility, and repeatability. The as-developed sensor's electrochemical outcomes indicate the superior performance inherent in the developed composite.

Bi2WO6 and TiS2 composite nanostructures displaying synergetic boosted energy storage in supercapacitor

The enhancement in the capacitance of a supercapacitor has been successfully achieved by synthesizing Bi2WO6 (BW), TiS2 (T), and Bi2WO6/TiS2 (BW/T) composites utilizing the hydrothermal process. The possible growth mechanism has also been presented. The morphological and structural characteristics of the cultivated samples were observed using FT-IR, XRD, SEM, EDS, and UV–vis spectroscopy techniques. TiS2 nano platelets uniformly dispersed across the hierarchically opened surface of Bi2WO6 in the synthesized hierarchical composite. This leads to an increase in surface porosity and surface area, which in turn enhances the transport of electrons and ions on the composite BW/T surface. The optimal electrode BW/T@40 % composite electrode shown a substantial enhancement in particular capacitance (1153.3 F/g) compared to the separate BW (523.7 F/g) and T (453.3 F/g) electrodes due to its rapid ion transfer, many active sites on its large surface area, and strong synergistic impact. Furthermore, the BW/T@40 % combination demonstrated exceptional stability, with over 92 % of its capacitance maintained after 4500th cycles and b value (0.71) proved the supercapacitor behavior. Therefore, BW/T@40 % binary metal oxide and sulfide composites exhibit improved specific capacitance and greatly prolonged life-cycle, confirming its potential use in high-performance energy storage devices.

Controlling Oxygen Vacancy Content by Varying Calcination Temperature to Enhance the Gas Sensing Performance of BiVO4 Material

Compared to gas sensors based on single metal oxide, gas sensors based on binary metal oxide semiconductors (MOS) offer a rich variety of structural types and hold great potential for excellent selectivity. Inspired by this, we synthesized BiVO4 powder through a stepwise reaction combining calcination with hydrothermal bath and investigated the influence of different calcination temperatures on its gas sensitivity performance. Our study revealed that BiVO4-600 exhibited optimal TEA gas sensing behavior at 225 °C, showing high response values (Ra/Rg = 43.4) and fast response/recovery times (15 s/52 s). Additionally, the sensor displayed high stability, repeatability, and exceptional selectivity. Preliminary research indicates that calcination temperature induces changes in the oxygen vacancy content of BiVO4, thus affecting its sensing performance.