Manganese Oxide Research Articles

(Industrial Electrochemistry and Electrochemical Engineering Division H. H. Dow Memorial Student Achievement Award) Tailoring Electrode-Electrolyte Interfaces through Non-Covalent Interactions for Electrochemical Energy Storage and Conversion

Li-ion batteries and fuel cells play essential roles in electrifying transportation. Central to the electrochemical systems is the electrode-electrolyte interface, where (electro)chemical surface reactions or intercalation occur, and its thermodynamic and kinetic properties determine the energy density, power density, and lifetime of the electrochemical devices. However, the molecular structures at the electrical double layer and reaction mechanisms remain poorly understood, hindering the rational material design for more efficient electrochemical devices. This talk focuses on the mechanisms of (electro)chemical reactions and charges transfer kinetics at the electrode-electrolyte interface, providing design principles based on non-covalent interactions in electrolytes.First, an in situ Fourier-transform infrared spectroscopy (FTIR) method was developed for Li-ion batteries, which revealed unique evidence for dehydrogenation of carbonate electrolytes on Ni-rich lithium nickel, manganese and cobalt oxides (NMC), accounting for interface impedance build-up and battery capacity fading. Based on the proposed mechanism, strategies on suppressing electrode and electrolyte reactivity were demonstrated to improve battery cycling. Next, the kinetic mechanism for ion intercalation at the electrode-electrolyte interface will be discussed. Li-ion concentration-dependent intercalation kinetics was demonstrated from charge-adjusted electrochemical experiments and fit into a coupled ion-electron transfer mechanism, which governed the current-dependent maximum capacity and power density of intercalation batteries. Finally, for electrocatalytic reactions central to fuel cell technologies, we demonstrated tuning interfacial hydrogen bonding through protic ionic liquids with different acid dissociation constants and organic solvents with different donor numbers to tailor oxygen-reduction reaction (ORR) and hydrogen evolution reaction (HER). Strengthening hydrogen bonding between ORR products and ionic liquids, or between interfacial water molecules facilitated proton-coupled electron transfer kinetics, revealed by in situ surface-enhanced infrared absorption spectroscopy and density functional theory (DFT) calculations. The study can pave the way for the electrolyte and electrode design of electrochemical storage devices with improved energy and power density and cycle life.

Grain Analysis of NCM Cathode Materials by ASTAR Technique and Its Effect on Battery Performance

Lithium-ion batteries (LIBs) are one of the most promising energy storage systems for portable electronic devices, electric vehicles, and renewable energy systems. Among the various cathode materials for LIBs, nickel cobalt manganese (NCM) oxide has attracted considerable attention due to its high specific capacity, good cycling stability, and appropriate cost for commercialization. However, Ni-rich NCM (Ni >80%) showed poor cyclability and huge gas evolution because of surface instability.Single crystal NCM has been suggested as a solution to these issues due to its excellent properties. However, it is difficult to quantify the degree of single crystallinity because it is so far subjective. In this study, we employed ASTAR technique (transmission electron microscopy combined with electron backscatter diffraction) to investigate the microstructural features of NCM cathode materials. Our ASTAR analysis showed that NCM cathode materials consist of complex grain and grain boundary structures with varying orientations and sizes. By analyzing the grain size and its morphology, we were able to define the single crystallinity of NCM cathode materials, including the poly NCM and single crystal NCM particles.Furthermore, we found that the grain size and its distribution significantly affects the battery performance and lifespan of NCM cathode materials. Specifically, the poly NCM particles exhibited a larger grain boundary and surface area compared to the single crystal NCM particles. The poly NCM particles also showed a faster DC-IR increase and a shorter lifespan than the single crystal NCM particles, indicating that the grain size has a critical influence on the battery performance and lifespan of NCM cathode materials.Our results provide insights into the design and optimization of NCM cathode materials for next-generation LIBs. By controlling the grain size and its distribution of NCM cathode materials, it is possible to enhance the battery performance and lifespan. Therefore, our study highlights the importance of understanding the microstructural features of NCM cathode materials for developing high-performance and stable LIBs.

Exploration of Local-Structure and Electrochemical Supercapacitive Performance of Hydrothermally Synthesized α-Fe2O3@Mn3O4@G Composite Electrodes

Due to growth in human population and upsurge in the energy needs, researchers have concentrating on the development of novel/advanced electrode materials. Batteries and supercapacitors (SCs) are most significant energy storage technologies present in contemporary gadgets like smartphones, medical equipment’s, electronic devices etc. However, in comparison to SCs, batteries have higher energy densities and lower power. To increase the energy density of SCs, researchers are engaging on developing hybrid SCs based on low-cost metal oxides/carbon based composite electrodes. Herein, we apply a hydrothermal approach to synthesize graphene supported iron and manganese oxide composite for SCs for the first time. The crystalline structure, phase purity, surface morphology, chemical bonding states, elemental composition of the synthesized samples were characterized by XRD, TEM, FE-SEM, XPS and EDS analysis. In addition, XAS (XANES and EXAFS) technique is used to examine the local structure of the composite samples. After confirming all the basic characterizations, the SC electrodes were constructed using synthesized samples, exhibiting a maximum specific capacitance of about 410 F/g at 5 mV/s and 800 F/g at 1 mA/cm2 in an aqueous electrolyte, which is quite higher than that of pristine Fe2O3, pristine Mn3O4, and Fe2O3-Mn3O4 composite electrodes. Furthermore, even after 2,000 cycles, the graphene composite electrode exhibits a capacitance retention of roughly 85% and a coulombic efficiency of nearly 80%. Furthermore, an asymmetric SC device was designed employing graphene composite as the positive electrode and AC as the negative electrode and investigated their performance using CV, GCD, and EIS analyses, These SC device exhibits extraordinary device performance. As a result, the present study provides a new path to fabricate affordable and flexible SC devices for use in real time applications in near future.

Construction of magnetic bimetallic oxide‐decorated attapulgite‐based adsorbents for arsenic ion adsorption

AbstractBACKGROUNDArsenic contamination can exert severe detrimental effects on the ecological environment and human health. It can cause acute or chronic poisoning, resulting in cell distortion or cancer when humans come into contact with or consume arsenic‐containing water. Adsorption technology is one of the effective methods for arsenic removal. In this study, using attapulgite (ATP) as a support for bimetallic iron–manganese oxides, a series of adsorbents (Fe‐Mn/ATP) with different manganese‐to‐iron molar ratios were prepared via the coprecipitation method. Scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy mapping, X‐ray diffraction and zeta potential measurements were used to analyze the structure and properties of Fe‐Mn/ATP. In addition, the adsorption performance of the material for arsenic ions was investigated by static adsorption and dynamic adsorption experiments.RESULTSA novel Fe‐Mn/ATP adsorbent was prepared using ATP as the raw material and manganese‐to‐iron molar ratio was 1:3 by coprecipitation at 60 °C for 1 h. The adsorption efficiency of arsenic ions was optimal at an Fe‐Mn/ATP dosage of 2 g L−1, pH 4 and a contact time of 10 min, reaching a maximum adsorption capacity of 38.27 mg g−1 at room temperature. The adsorption process followed the pseudo‐second‐order kinetic model and the Langmuir isotherm adsorption model, indicating that arsenic ion adsorption by Fe‐Mn/ATP was mainly monolayer chemical adsorption. Furthermore, Fe‐Mn/ATP showed a removal rate for arsenic ions of over 80% after four cycles of regeneration, revealing a great potential for practical application.CONCLUSIONThis study offers a promising Fe‐Mn/ATP adsorbent for removal of arsenic ions from wastewater. © 2024 Society of Chemical Industry (SCI).

Next-Generation Batteries through Advanced 3D Electrode and Material Concepts

With the rise of renewable energy sources, energy storage solutions become increasingly important as they represent a key feature for secure and constant power supply. In this regard, battery systems play a crucial role in accelerating the transition towards sustainable and green energy sources. To meet the rising global demand, further advancement of the battery technology is imperative. One optimization pathway is to use battery materials that are more sustainable while also yielding improved electrochemical performance, contributing to both environmental and functional advancements. However, innovation must go beyond the material level, and new electrode design approaches for an efficient combination of high power and high energy systems are necessary.In this context, the three-dimensional (3D) battery concept with its increased exposed electrode surface, shows a great promise for enhanced electrochemical performance compared to the conventional flat designs of state-of-the-art electrodes. Targeting at the bottleneck of high power/high energy density systems, the incorporation of micro-structured channels within the electrodes improves lithium-ion diffusion pathways and minimize strain from volume expansion during electrochemical cycling.Our focus is the investigation of 3D electrode architectures generated by laser-processing techniques such as ultrafast laser ablation and laser-assisted printing. Working with ultrafast lasers offers the possibility to process materials while reducing thermal impact and allows the creation of well-designed and controllable electrode surface topographies. The adoption of this concept has already shown great impact in enhancing the high-rate capability and lifetime of conventional electrodes in lithium-ion batteries.[1-3] Expanding the scope, this work explores the applicability of laser-generated 3D electrode architectures to next-generation battery active materials such as high-voltage lithium nickel manganese oxide (LNMO) composites. On anode side, silicon/graphite and amorphous carbon is extensively investigated for lithium-ion batteries and sodium-ion batteries, respectively. To understand the impact of the manufacturing process, electrochemical evaluations are complemented by findings from laser-induced breakdown spectroscopy, SEM-EDX, Raman measurements, and Auger electron spectroscopy.In conclusion, this contribution highlights the promising advancements achieved by applying laser-generated 3D electrode architectures to next-generation battery materials and aims to provide valuable insights into this exciting frontier of battery research.[1] W. Pfleging, Nanophotonics 7 (2018) 549–573.[2] W. Pfleging, Int. J. Extrem. Manuf. 3 (2021) 012002.[3] M. Zaeh, Appl. Energy 303 (2021), 117693.

Development of Organic Positive Electrodes for Rechargeable Aqueous Zinc-Ion Batteries for Stationary Energy Storage Systems

The rising concern towards the amount of anthropogenic carbon emissions and their effects on the environment has motivated the transition away from fossil fuels. The implementation of renewable energy sources has promoted the decarbonization of the power sector, but the variability of wind and solar energy necessitates the parallel deployment of high-performance energy storage infrastructure to ensure a reliable on-demand supply of green electricity to the grid. To this end, aqueous rechargeable zinc-ion batteries (ZIBs) are a promising new option for stationary energy storage owing to their high safety and low cost, when compared to established storage technologies like lithium-ion batteries. However, ZIBs are still limited by several technological challenges that hinder their uptake for commercial energy storage installations. In particular, the positive electrode materials, mostly comprised of metal oxides, are restraining the energy density and stability of the batteries and are yet under investigation. Low cost, long cycle life, and natural abundance are required properties of materials used in batteries for stationary energy storage. The search for materials with these properties has motivated the investigation of alternatives to metal oxides. One group of materials attracting considerable research attention is organic compounds which offer advantages like their natural abundance and high theoretical capacities. In this work, we developed an organic positive electrode for ZIBs using carbonyl groups as redox-active centers to provide energy storage capacity at round-trip energy efficiencies that are higher than the conventionally utilized manganese oxide electrodes. Furthermore, we investigated the effects of the conductive carbon additive on the deliverable capacity of the battery and elucidated the charge storage mechanism of this positive electrode material through detailed characterization. The results indicated that both Zn2+ and H+ are involved in the energy storage process of this organic electrode material. In addition to studying the energy storage process, degradation mechanisms were identified through nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Both dissolution of the reduced form of the active material from the electrode and the formation of unwanted decomposition products are important contributors to the capacity fade of the battery. The technological and scientific insights provided in this presentation will thereby contribute towards the development of high-performance and naturally abundant electrode materials for the next generation of ZIBs to enable clean energy grid storage.

Highly efficient adsorption of congo red and methyl orange dyes using mesoporous α-Mn2O3 nanoparticles synthesized with Pyracantha angustofolia fruit extract

Due to the many applications of manganese oxides in water treatment, this research aimed to synthesize α-Mn2O3 nanoparticles through a green method and investigate the dye adsorption capacity of them. The α-Mn2O3 nanoparticles were successfully synthesized using KMnO4 and aqueous extract of Pyracantha angustofolia fruits under hydrothermal conditions and calcination. The products were identified using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM) analyses. The adsorption capacity of methyl orange (MO) and Congo red (CR) dyes were evaluated at different concentrations (25, 50, and 75 ppm) using α-Mn2O3 nanoparticles. Results revealed the spherical and porous structure of α-Mn2O3 nanoparticles with a specific surface area of 21.7 m2.g-1. Dye removal significantly increased with pH decrement. The adsorption capacity for MO and CR was 73.07 and 70.70 mg.g−1, respectively. The adsorption data of both dyes followed a pseudo-second-order kinetic model. The best fitted models for MO and CR adsorption were the Langmuir isotherm and the Dubinin–Radushkevich, respectively. In addition, a possible adsorption mechanism was proposed for both dyes. The findings showed that α-Mn2O3 nanoparticles are very efficient adsorbents for removing anionic dyes.

Zinc-Lithium Dual Ion Deep Eutectic Mixtures As Electrolyte for Stable Zinc-Based Hybrid Batteries

Anode-free zinc batteries (AFZBs) are proposed as promising energy storage systems due to their high energy density, low cost, high safety, and easy production characteristics. However, the high reactivity of water molecules can induce passivation and dendritic growth within zinc-based aqueous batteries, thereby affecting the durability of the battery.A deep eutectic solvent (DES) is a solvent created through a suitable combination of salts or zwitterions, acting as hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD). Its melting point is considerably lower than the combined melting points of its components, attributed to its engagement in a complex network of hydrogen bonds. Due to the distinctive properties of deep eutectic solvents, they possess a notable ability to decrease water activity substantially Consequently, we design a novel deep eutectic electrolyte and examine its performance on zinc-based batteries.This electrolyte design composed of 1 mole of zinc chloride combing with 1 mole of lithium acetate as the ion sources. Subsequently, 4 moles of N-methyl acetamide are added to the mixture, and the resulting mixture is heated to 353 K with continuous stirring until a liquid state of deep eutectic electrolyte is achieved. Due to the high viscosity of the electrolyte, different cosolvents, namely 2 moles of methanol and 2 moles of acetonitrile, are introduced after cooling to improve the viscosity. The positive electrode material, lithium manganese oxide (LiMn2O4, LMO), is employed to construct a Zn//LMO half-cell and conduct electrochemical tests.The study commences by investigating the electrochemical performance of Zn//Zn symmetric cells, Zn//Cu asymmetric cells, Zn//LMO half-cell, and Cu//LMO anode-free cells, both with and without the addition of cosolvents (methanol, acetonitrile). Various electrochemical tests, including AC impedance, cyclic voltammetry (CV), and linear sweep voltammetry (LSV), are then performed. In addition, Raman spectroscopy and Fourier-transform infrared spectroscopy techniques will be utilized to glean the solvation structure of the electrolyte. Lastly, viscosity, conductivity, and differential scanning calorimetry (DCS) tests will be also performed.The results demonstrate that in the Zn//Zn symmetric cell, the addition of cosolvent reduces the overpotential of Zn plating/stripping by 0.6 V compared to the case without cosolvent. Furthermore, in the Zn//Cu asymmetric cell, the inclusion of cosolvent exhibits a remarkable Coulombic efficiency of 99.9% after 450 cycles at a current density of 0.5 mA/cm². In the Zn//LMO half-cell, the best cyclic performance is observed with 2 moles of methanol, maintaining a specific capacity of 80 mAh/g after 900 cycles at a current density of 100 mA/g, with a capacitance retention of 97.5%. For the Cu//LMO anode-free cell, a specific capacity of 70 mAh/g is retained with a capacitance retention of 96.5% after 900 cycles at a current density of 100 mA/g. Additionally, a Coulombic efficiency of 96.5% is maintained after 900 cycles. Compared to methanol cosolvent, acetonitrile as cosolvent in the Zn//LMO half-cell and Cu//LMO anode-free cell exhibit inferior performance. After 900 cycles at a current density of 100 mA/g, exhibits a significantly reduced specific capacity of only 20 mAh/g, with a capacitance retention of only 62.5%.The electrolyte analysis reveals that the Raman peak at 870 cm-1 and the FTIR peak at 990 cm-1, corresponding to N-CH3 vibrations, for electrolytes showing blue shift compared to pure N-methyl acetamide. Additionally, a blue shift is also observed in the Raman peak at 1340 cm-1 and the FTIR peak at 1160 cm-1 in, corresponding to N-C vibrations. These shifts suggest that N-methyl acetamide coordinates with zinc ion and lithium ion, forming a deep eutectic electrolyte and altering the structure of the solvated shell as results. The addition of 2 moles of methanol, the conductivity is improved and the viscosity reduced significantly. The DCS shows the freezing point of the deep eutectic electrolyte is decreased compared to N-methyl acetamide, reaching a temperature of around 214 K.This study demonstrate that deep eutectic solvents can alter the structure of the solvated shell within the electrolyte, significantly reduce the activity of free water, and mitigate passivation and dendrite formation on the zinc anode surface. This leads to enhanced stability in the electrochemical performance of the battery. Figure 1

Enhancing low-temperature lithium-ion battery performance under high-rate conditions with niobium oxides

Low-temperature operation (−20 °C and below) under high-rate conditions is a critical deficiency for lithium-ion batteries. To achieve size, weight, and power requirements tailored for demanding applications, novel materials are needed to sustain high performance. In the present study, we synthesize a series of niobate anode materials (Nb2O5, Nb2O5–x, and Nb12O29) and tailor their particle size, defect nature, and electrical/ionic conductivity to enable high-performance operation at −20 °C under high-rate conditions (1.2C–2C). When paired with lithium manganese oxide (LMO) in a full-cell configuration, the Nb2O5–x-based full-cells achieve high-rate capability (∼90 mAh/g up to 2C cycling rate at −20 °C) and great long-term stability (>98% retention up to 50 cycles at −20 °C). During a simulated 30 min duty cycling test synthesized from measured data from an actual drone flight (continuous range of 1.2C–2C cycling rates), the Nb2O5–x||LMO cell enables full discharge at −20 °C, with only a 0.3 V voltage drop when compared to duty cycling at room temperature. The work presented herein demonstrates the future possibilities of expanding the operational capabilities of lithium-ion batteries.

Unveiling the role of heterophase nanostructure in MnO2-based colorimetric sensors for ascorbic acid detection.

Nanozymes based on manganese oxide (MnO2) are demonstrated to be promising probes in colorimetric sensing applications. In this study, the r-MnO2/β-MnO2 heterophase nanostructure was simply prepared by a calcination process with controllable temperature. The characterization of the nanostructured material was confirmed by SEM, UV-vis spectroscopy, Raman, TGA-DSC, and XRD analysis. The r-MnO2/β-MnO2 exhibits a remarkably good catalytic activity in the oxidation process of 3,3',5,5'-tetramethylbenzidine (TMB) compared withthe r-MnO2 or Mn2O3 nanostructure owing to its heterophase junctions. The enhanced performance of the colorimetric sensor for ascorbic acid (AA) detection was investigated using the r-MnO2/β-MnO2 heterophase nanostructure as probe. The r-MnO2/β-MnO2 material enhanced the monitoring of AA in the wide linear range from 1µM to 50μM with alimit of detection of0.84µM. This work presents a promising and straightforward approach for the construction of MnO2-based colorimetric sensor and their practical application in plant growth monitoring.

Effect of hydrothermal temperature variation on electrochemical performance of manganese oxide thin films for supercapacitor application

Effect of hydrothermal temperature variation on electrochemical performance of manganese oxide thin films for supercapacitor application

Optimizing Energy Storage Performance: In situ Synthesized Manganese Oxide (Mn3O4) Nanoparticle‐Based Symmetric Supercapacitor on a Paper Substrate

AbstractIn this study, a redox reaction is employed to synthesize manganese oxide (Mn3O4) nanoparticles using potassium permanganate as a precursor in the presence of diethyl amine. The structural characterization reveals the formation of the tetragonal phase of Mn3O4 nanoparticles with a space group of I41/amd. A free‐standing Mn3O4‐based paper electrode is fabricated and its electrochemical performances are investigated. The electrode exhibits a maximum specific capacitance value of ~353 F g−1 and an areal capacitance of ~530 mF cm−2 at a current density of 0.2 A g−1. A symmetric supercapacitor‐based device is also designed using Mn3O4 nanoparticles as an active material in a gel electrolyte configuration. The Mn3O4 device achieves specific and areal capacity values of ~208 mAh g−1 and 260 mA cm−2, respectively, at a current density of 0.3 A g−1. The device delivers maximum energy and power density values of ~104 Wh kg−1 and ~220 W kg−1, respectively, with ~92 % specific capacity retention at 0.3 A g−1 after 5000 cycles. The above results suggest that the Mn3O4‐based device has the potential for energy storage applications.

Tagetes erecta-Mediated Biosynthesis of Mn3O4 Nanoparticles: Structural, Electrochemical, and Biological Investigations.

Mn3O4 nanoparticles (NPs) find diverse applications in the fields of medicine, biomedicine, biosensors, water treatment and purification, electronics, electrochemistry, and photoelectronics. The production of Mn3O4 NPs was reported earlier through various physical, chemical, and green routes, but no studies have still been performed on their biosynthesis from Tagetes erecta. We synthesized manganese oxide NPs, i.e., (Mn3O4)L and (Mn3O4)P NPs, by utilizing leaves and petals, respectively, of T. erecta as reducing and stabilizing agents. The investigated green path is eco-friendly and does not involve any hazardous raw materials. The structural properties of NPs were determined by X-ray diffraction (XRD) analysis, spectroscopies (Fourier transform infrared (FTIR), Raman, and UV-visible), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The NPs were also evaluated for their electrochemical properties by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). XRD analysis was performed to verify their tetragonal geometry, and the crystallite size (19.24 nm) of (Mn3O4)P was smaller than that (20.84 nm) of (Mn3O4)L NPs. SEM images displayed a porous and spherical morphology with a diameter of 14-35 nm. FTIR spectra of (Mn3O4)L and (Mn3O4)P displayed Mn-O vibrations at 605.69 and 616.87 cm-1, respectively, and the hydrous nature of the material. Raman spectroscopy revealed the existence of tetrahedral and octahedral units along with A1g, T2g, and Eg active modes of Mn3O4 and 2TO mode. UV-visible analyses of (Mn3O4)L and (Mn3O4)P NPs showed absorption peaks at 272.3 and 268.8 nm, along with band gaps of 4.83 and 5.49 eV, respectively. TGA curves displayed good thermal stabilities up to 600 °C and a loss of moisture content. DSC curves exhibited exothermic/endothermic peaks with glass transition temperatures of 258.9 and 308.7 °C for (Mn3O4)P and (Mn3O4)L, respectively. The CV curves showed redox peaks and confirmed that the electrochemical reaction takes place in the Mn3O4 material. GCD scans revealed the capacitive behavior of NPs and their suitability as electrodes in energy storage devices. However, (Mn3O4)L will act as a good material for energy storage applications as compared to (Mn3O4)P NPs. The synthesized NPs were also tested for their antibacterial efficacy by biofilm inhibition and agar well diffusion methods. The NPs showed higher activities against Staphylococcus aureus (Gram-positive) than against Escherichia coli (Gram-negative), and (Mn3O4)P was more bioactive than (Mn3O4)L.

Unlocking enhanced new type of safe open system lithium-ion battery performance: Mn3O4 nano-cubes and their sulfur mixers cathode material

In the pursuit of advancing lithium-ion (Li-ion) battery technology towards enhanced safety and performance, we present research study on the synthesis and evaluation of manganese oxide-based cathode materials. Different phases of manganese oxides (Mn3O4 and MnO2), alongside their different ratio of two manganese oxides phases and Mn3O4 with sulfur (S) combination, we employed a simple hydrothermal and solid-state grinding techniques. Characterized by field emission transmission electron microscopy (FE-TEM), our synthesized materials revealed distinct phases of MnO2 and Mn3O4 accompanied by nanorods (NRs) and nanocubes (NCs) morphologies, respectively. We conducted a comprehensive assessment of the Li-ion battery performance of these materials, initially without S, within a new type of safe open system framework. Notably, Mn3O4 NCs (MNCs) developed as important, exhibiting a maximum discharge capacity of 346.03 mAh/g at a constant current discharging rate of 0.5 A/g. We introduced 30 % of S into 70 % of the MNCs matrix to form the MNCSs-73 composite, resulting in rather moderate enhancement in capacity performance. The MNCSs-73 displayed an exposed discharge capacity of approximately 394.8 mAh/g under identical testing conditions. Our findings underscore the exceptional potential of MNCs and MNCSs-73 composites cathode materials for highly suitable for open system novel safe Li-ion battery applications and other energy storage research field.

Unlocking the potential of cation vacancy-enriched ZnMn1.75O4 cathode for advanced aqueous aluminum-ion batteries

Manganese oxides are widely utilized in aqueous aluminum-ion batteries (AIBs) due to their high voltage and diverse crystal structures. However, the Jahn-Teller effect induced by Mn-O6 units results in irreversible structural damage. Here, we synthesized ZnMn1.75O4 (ZMO) cathodes loaded onto a carbon framework with manganese vacancies (VMn) for AIBs through ion substitution, manganese extraction, and carbonization on Mn-MIL. VMn stabilizes the ZMO structure by damping Mn-O bond vibrations and fosters Mn-O-C bonds between oxide particles and the carbon framework, effectively suppressing irreversible Mn2+ dissolution. Vacancy-modified cathodes provide more ion insertion sites, promoting ion diffusion. Ex-situ characterization revealed dominant H+ and Al3+ insertion behavior during different voltage regimes. Upon initial discharge, ion insertion into vacant lattice sites causes lattice distortions in adjacent unit cells, prompting ZMO to undergo a crystal structure transition and partial zinc deintercalation, resulting in a more stable cathode structure. Therefore, Al/ZMO batteries exhibit enhanced electrochemical performance.

Gravure Printed Composites Based on Lithium Manganese Oxide: A Study Case for Li‐Ion Batteries Manufacturing

AbstractAimed by the increasing interest in the field of printed batteries, the study recently has demonstrated the possibility to successfully gravure print composites working as electrodes for Li‐ion batteries. Gravure is one of the most appealing printing technique for the mass production of functional layers due to its unique ability to couple high speed and high resolution. The ink formulation is challenging because of the low viscosity ink requirement which makes difficult to obtain the proper functionality of the layer, especially in case of composite materials like electrodes, and a mass loading suitable for practical applications. Changing a material of the composite implies the study of a new gravure ink in terms of formulation and preparation process. Ruling the ink preparation can strongly decrease the process time promoting the industrial use of the gravure printing. For this reason, the study proposes a methodology, mainly based on the capillary number, able to suggest the best receipt for each specific ink. Here, a study case is reported, using lithium manganese oxide (LMO) as active material for the gravure printed cathode manufacturing. Such work gives the possibility to show the proposed methodology for ruling the ink preparation.

Fabrication of iron manganese oxide-reduced graphene oxide nanocomposite: A highly effective synergistic electrocatalyst for sensitive metronidazole detection

Efficient 2D-inorganic spinel perovskites nanostructure materials are used as potential candidates for highly sensitive detection of harmful substances present in the environment. In this regard, a facile one-pot hydrothermal synthesis was employed to fabricate nanocomposite material containing iron manganese oxide (FeMn2O4) decorated with reduced graphene oxide (rGO) which is used as an electrochemical detection of metronidazole (MTZ). The crystalline nature and structural insights of the as-synthesized FeMn2O4-rGO nanocomposite were established using various spectroscopic and electrochemical techniques. Distinctively FeMn2O4-rGO nanocomposite fashioned glassy carbon electrode (GCE) showed excellent linear range (0.01–512.2 μM), sensitivity (71.4 μA mM−1 cm−2), limit of detection (0.0129 μM), reproducibility, stability and resist-interference capability towards metronidazole (MTZ) antibiotic drug. In addition, the fabricated FeMn2O4-rGO/GCE electrochemical sensor exhibited a remarkable MTZ detection in spiked water as well as urine samples with better recovery percentages supporting its facile and feasible nature for environmental applications. The present work established the fabrication of FeMn2O4-rGO/GCE nanocomposite for effective determination of antibiotic drugs in real sample analysis.

Plasma‐assisted Surface Engineering to Stabilize Mn3+ in Electrodeposited Manganese Oxide Films for Water Oxidation

Manganese oxide is a unique type of transition metal oxide that effectively functions as a catalyst for the oxygen evolution reaction (OER). Here, manganese oxide (MnOx) polymorphs are synthesized through electrochemical deposition and treated with an atmospheric pressure plasma jet (APPJ). The APPJ surface treatment can generate numerous oxygen vacancies and modify the crystallinity of the MnOx films, which can enhance the long‐term stability of the MnOx films by stabilizing the Mn3+ content in the highly oxidizing environment. The increase in Mn3+ content and concentration of oxygen vacancies in the material synergistically increase the adsorption capacity of OH* and the electron‐transferring capacity of MnOx films in the OER process, making them more stable and effective for OER. MnOx films treated with APPJ exhibit significantly higher activity, better stability, and lower Tafel slopes for OER than untreated MnOx films. The MnOx films treated with APPJ can remain stable for up to 92 hours during OER with a current density of 10 mA cm‐2, with an onset overpotential of 310 mV. This strategy, which combines APPJ surface treatment techniques with electrodeposition methods, is innovative in the surface modification of manganese oxides with mixed valences to create OER catalysts with stable Mn3+ content.

The potential linkage between sediment oxygen demand and microbes and its contribution to the dissolved oxygen depletion in the Gan River.

The role of sediment oxygen demand (SOD) in causing dissolved oxygen (DO) depletion is widely acknowledged, with previous studies mainly focusing on chemical and biological SOD separately. However, the relationship between the putative functions of sediment microbes and SOD, and their impact on DO depletion in overlying water, remains unclear. In this study, DO depletion was observed in the downstream of the Gan River during the summer. Sediments were sampled from three downstream sites (YZ, Down1, and Down2) and one upstream site (CK) as a control. Aquatic physicochemical parameters and SOD levels were measured, and microbial functions were inferred from taxonomic genes through analyses of the 16S rRNA gene. The results showed that DO depletion sites exhibited a higher SOD rate compared to CK. The microbial community structure was influenced by the spatial variation of Proteobacteria, Chloroflexi, and Bacteroidota, with total organic carbon (TOC) content acting as a significant environmental driver. A negative correlation was observed between microbial diversity and DO concentration (p < 0.05). Aerobic microbes were more abundant in DO depletion sites, particularly Proteobacteria. Microbes involved in various biogeochemical cycles, such as carbon (methane oxidation, methanotrophs, and methylotrophs), nitrogen (nitrification and denitrification), sulfur (sulfide and sulfur compound oxidation), and manganese cycles (manganese oxidation), exhibited higher abundance in DO depletion sites, except for the iron cycle (iron oxidation). These processes were negatively correlated with DO concentration and positively with SOD (p < 0.05). Overall, the results highlight that aerobic bacteria's metabolic processes consume oxygen, increasing the SOD rate and contributing to DO depletion in the overlying water. Additionally, the study underscores the importance of targeting the removal of in situ microbial molecular mechanisms associated with toxic H2S and CH4 to support reoxygenation efforts in rehabilitating DO depletion sites in the Gan River, aiding in identifying factors controlling DO consumption and offering practical value for the river's restoration and management.

Effect of Manganese Oxide Doping of Tin Oxide Thin Films on the Optical and Structural Properties

Tin oxide pure and manganese oxide doped (SnO2:Mn2O3) films were grown on a glass substrate in vacuum by pulsed laser deposition (PLD) technique (using Nd: YAG Laser) at different ratios of Mn2O3 (0, 3, 5, 7, 9) % wt. The structural and optical properties were studied. The X-ray diffraction (XRD) studies showed the structure nature of the films to be polycrystalline and rutile tetragonal. The optical transmittance spectra and optical constants of the prepared thin films, such as extinction coefficient (k), refractive index (n), and real (εr) and imaginary parts (εi) of the dielectric constant, were investigated. The values of the energy band gap increased from 3.5 eV to 3.55 eV with increasing the doping concentration.