Manganese Oxide Nanoparticles Research Articles

Room‐Temperature Solvent‐Free Synthesis of Three‐Dimensional Flower‐Like α‐MnO2 Microspheres for Supercapacitor Application

AbstractConstructing manganese oxide nanoparticles with different crystal structures and morphologies is crucial for the development of improved supercapacitors. Here, zero‐dimensional (0D) α‐MnO2 and δ‐MnO2 nanoparticles were first synthesized by an ultra‐simple solvent‐free synthetic strategy. The α‐MnO2 nanoparticles exhibited better performance for supercapacitors than δ‐MnO2 nanoparticles due to a higher specific surface area and accelerated electrical charge transfer. Two‐dimensional (2D) α‐MnO2 nanosheets and three‐dimensional (3D) flower‐like α‐MnO2 microspheres were also fabricated by the inclusion of surfactants to investigate the effects of morphology on electrochemical storage capacity with the assistance of different surfactants. Notably, 3D α‐MnO2 microspheres exhibited enhanced electrochemical properties than 0D α‐MnO2 nanoparticles and 2D α‐MnO2 nanosheets for supercapacitors, and generated a favorable specific capacitance of 212.8 F g−1 at 1 A g−1, primarily originating from high porosity, which allows the full infiltration of electrolytes and the rapid shuttling of ions. This work thus describes a simple strategy for the synthesis of 2D nanosheets and 3D self‐assembled nanostructures of MnO2 for application in supercapacitor development.

Electrochemical Fabrication and Characterization of a Gold-Polyaniline /Multi-walled Carbon Nanotubes/Manganese Dioxide Composite Electrode

Objectives: Electrochemical fabrication and characterization of a gold-polyaniline/multi-walled carbon nanotubes/manganese dioxide (Au-PANI/MWCNT/MnO2) composite electrode. Methods: The MnO2 nanoparticles (NPs) were prepared by heating 1% Mn(NO3)2.4H2O at 100 0C for 24 h and characterized by using Fourier transform infrared spectroscopy (FTIR) and Ultraviolet/visible (UV/Vis) spectrophotometry. The size and shape of the NPs were determined from the transmission electron microscopic image. MWCNTs were functionalized with carboxyl groups on their sidewalls by sonicating in H2SO4:HNO3 (3:1, v/v) for 12 h at 40 kHz. The functionalization was further confirmed through UV/Vis spectrophotometry. The working Au surface was first activated and then electropolymerized by using 50 μl of 0.005% C6H5NH2 in 01 N HCl followed by electrodeposition with 0.1% each of the c-MWCNTs and manganese oxide NPs through 20 cycles of cyclic voltammetry (-0.2-0.9 mV) at the rate of 20 mV/s. The Au-PANI/MWCNT/MnO2 composite was then characterized by using FTIR spectra and scanning electron microscopy. Findings: An Au-PANI/MWCNT/MnO2 composite electrode was fabricated and characterized. Novelty: The nanocomposite electrode was designed by using screen printed electrode, which is very simple to construct, portable, and economic. The composite can be used to design a sensors or sensor array in future. Keywords: Electrochemical Fabrication, Manganese Dioxide, Multi-walled Carbon Nanotubes, Nanocomposite Synthesis, Screen Printed Electrodes

Investigations on Electrochemical Performance of Hausmannite Manganese Oxide Nanoparticles in KOH and Na2SO4 Electrolytes for Energy Storage Applications

The hausmannite phase manganese oxide nanoparticles (NPs) were prepared by a simple chemical reflux method. Powder X-ray diffraction shows the well-crystalline structure of Mn3O4 spinel. Fourier-transform infrared spectroscopy study exhibited the Mn–O functional group vibrations in the hausmannite NPs. UV–visible spectroscopy study reveals that the optical bandgap energy of the manganese oxide nanoparticles is about 3.1[Formula: see text]eV. The scanning electron microscopy (SEM) analysis shows that the surface morphologies of the manganese oxide nanoparticles are wrinkle structures. Cyclic voltammetry studies were carried out to the electrode of Mn3O4 NPs in KOH and Na2SO4. The charge–discharge analysis and impedance spectroscopy method analysis were made on Mn3O4 NPs to understand the electrochemical performance. The ability of synthesized Mn3O4 NPs electrodes was analyzed and compared with the existing materials for the supercapacitor applications.

HMO-incorporated electrospun nanofiber recyclable membranes: Characterization and adsorptive performance for Pb(II) and As(V)

In the present work, hydrous manganese oxide (HMO) nanoparticles have been synthesized and successfully impregnated into polyacrylonitrile (PAN) nanofibers to obtain HMO-PAN composite electrospun nanofiber membranes (ENMs), via electrospinning technique. Characterization of the synthesized nanoparticles and composite ENMs using techniques high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X-ray diffraction was performed. The adsorption viability of HMO-PAN composite ENMs as for removal of lead (Pb(II)) and arsenic (As(V)) from aqueous solution was evaluated using batch adsorption technique. HMO-PAN composite ENM preferably sequestrate As(V) and Pb(II) ions at pH 5.0 and 7.0, respectively. The maximum Langmuir adsorption capacity obtained for lead and arsenic was 194.4 mg/g and 95.7 mg/g, respectively at 318 K. During regeneration the material retained about 88% (for lead) and 83% (for arsenic) of adsorption capacity after five adsorption-desorption cycles indicating high potential for long-term application. Hence, the synthesized nanocomposite provides facile fabrication, excellent regeneration ability, and easy recovery without leaching, proving to be a promising adsorbent for uptake of Pb(II) and As(V) from aqueous solutions

Colloidal MnOX NPs/Carbon sheets nanocomposite synthesis by laser ablation in liquids

MnOxNPs/Cnanosheets composite based colloidal suspensions were synthesized using the laser ablation in liquids technique. The colloids were obtained by ablating a manganese target immersed in a carbon nanosheets suspension, which was previously prepared through laser fragmentation of microsized carbon powder suspended in acetone. The microsized carbon powder was characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The as-obtained nanostructures were characterized by Raman microspectroscopy and transmission electron microscopy (TEM). Raman microspectroscopy results indicate that the composite is constituted by manganese oxide (a mixture of the MnO and Mn3O4 crystalline phases) and carbon. TEM images show that the nanocomposite is composed by manganese oxide nanoparticles embedded in carbon nanosheets. The colloidal suspensions were studied by means of photoluminescence (PL). The two distinct colloidal suspensions (i. e. the carbon nanosheets colloid and the MnOx NPs/C nanosheets composite colloid) show PL. The carbon nanosheets PL is enhanced significantly (in the order of 2.5 times) when the MnOx NPs have been synthesized in the composite. Also, the MnOx NPs provide an intense UV emission to the composite. Several potential applications can be envisioned for this MnOx NPs/C nanosheets composite in the fields of opto-electronics and biomedicine.

Effect of calcination temperature on morphology and phase transformation of MnO2 nanoparticles: A step towards green synthesis for reactive dye adsorption

Green synthesis of manganese oxide nanoparticles (NPs) was carried out by sol-gel method using Acacia Concinna fruit extract for removal of reactive dye. The effect of calcination temperature on its morphology was investigated. α-MnO2 and Mn3O4 NPs were synthesized at 400 °C and 900 °C respectively and were characterized by PXRD, SEM, TEM, FTIR, BET, Raman and TGA. As-synthesized MnO2 NPs were investigated for the adsorption of Reactive Blue 21 (RB-21) dye. The effect of pH, adsorbent dose, agitation speed, initial dye concentration and temperature on dye removal was explored. pHpzc was calculated from zeta potential study showing positive surface charge below pH 3.18 resulting in electrostatic force of attraction between adsorbate and adsorbent. Both linear and non-linear regression approaches were utilised for the fitting of kinetic models and adsorption isotherms. Adsorption data follows a pseudo second order kinetics and fits well with the Freundlich isotherm model. Thermodynamic parameters such as ΔHo, ΔSo and ΔGo were determined. The dye removal efficiency, in case of MnO2 NPs at pH 3.0 was obtained to be 98% whereas for Mn3O4, no such dye adsorption was observed. The mechanism of adsorption was studied theoretically confirming π-π interaction and H-bonding between the MnO2 and RB dye molecules.

Geochemistry of barium ions associated with biogenic manganese oxide nanoparticles generated by a fungus strain: Implications for radium sequestration in uranium mill tailings

Biogenic Mn oxides are reactive and ubiquitous in many Earth surface environments, yet their role in radionuclide sequestration at U mill-tailings sites still require an improved understanding at the nano- and molecular-scales. This study concerns the uptake of Ba, utilized as a safe and chemically appropriate surrogate for radioactive Ra, by biogenic Mn oxides produced by a fungal species, Coprinopsis urticicola, isolated from the mine water of the Ningyo-toge U mine, Okayama, Japan. The biogenic Mn oxides were identified as birnessite nanocrystals <10 nm in width having many vacancy sites in the MnO6 octahedral layers. Ba2+ adsorption experiments using biogenic birnessite were conducted at pH 6.00 ± 0.02 with the initial Ba concentrations ranging from 10–8 to 10–3 mol/L. The apparent distribution coefficient, Kd, was calculated to be 103.8 L/g for biogenic birnessite, which is comparable to the apparent Kd of Ra in the mill tailings pond at Ningyo-toge. Both in adsorption and coprecipitation experiments, extended X-ray absorption fine edge structure analysis of Ba L3 edge revealed that the Ba atom forms an inner-sphere complex with O atoms of the MnO6 layer. A slightly greater coordination number for coprecipitated Ba may be attributed to the formation of BaO binding to the newly overlying MnO6 layer during coprecipitation. Static desorption experiments for 7 days reveal that the steady-state release rate of adsorbed Ba is ∼1.4 times faster than that of the coprecipitated Ba, when the Ba concentration in the initial loading solution was ∼10–8 mol/L, indicating that the release of intercalated (coprecipitation) Ba to solution is retarded. The present study demonstrates the importance of fungus-generated Mn oxides as an efficient absorber of Ba2+, and likely Ra2+, among soil compounds in U mill-tailings. This may be applicable to other contaminated sites due to the ubiquitous occurrence of fungi in the environment.

КОМПОЗИТНЫЕ ЭЛЕКТРОДЫ С/MnO2 ДЛЯ ЭЛЕКТРОХИМИЧЕСКИХ КОНДЕНСАТОРОВ НА ВОДНОМ ЭЛЕКТРОЛИТЕ

The electrochemical properties of C/MnO2 composite materials in 1 M sodium sulfate solution were investigated using the methods of cyclic voltammetry, galvanostatic charge-discharge and impedance spectroscopy. It was shown that the capacitive characteristics of the electrodes depend on the nature and the method of obtaining manganese oxide nanoparticles. It was established that the material containing manganese oxide obtained using isoamyl alcohol as a reducing agent has high electrochemical characteristics.

An investigation on the adsorption of methyl orange from water by MnO2-modified diatomite

The MnO2-modified diatomite was obtained by wet chemical methods. The specific structure of the material has been determined by modern physicochemical methods. The results showed that the surface of diatomite was coated by the manganese oxide nanoparticles. The prepared MnO2-diatomite material is a good adsorbent for the removal methyl orange (MO) in water. The adsorption kinetics of MO on modulation materials are consistent with the pseudo-second-order kinetics model. Therefore, MnO2-modified diatomite materials could be promising sorbents for removing MO.

Electromagnetic field’s effect on enhanced oil recovery using magnetic nanoparticles: Microfluidic experimental approach

The enhanced oil recovery methods such as thermal, chemical, and flooding methods have been utilized for increasing the production of residual oil in reservoirs. In recent years, some researches were conducted on newer methods such as injecting nanofluid and improving its performance utilizing new technologies, i.e., electromagnetic fields to improve oil recovery. In this study, the effect of the electromagnetic field on the oil recovery factor was investigated. First, Iron Oxide nanoparticle was synthesized by the co-precipitation technique and then its surface was functionalized using citric acid. Furthermore, Manganese Oxide nanoparticle which has not used in previous studies in enhanced oil recovery operations despite its suitable electromagnetic properties were used in this research. For analyzing the effect of nanoparticles and electromagnetic field on oil recovery, flooding experiments were performed in micromodel and the results of these experiments were compared to those of flooding without any effect by the electromagnetic field. The Iron Oxide nanoparticles showed better potential in comparison with Manganese Oxide nanoparticles in the oil recovery process. The results showed that by increase in nanoparticles concentration, the oil recovery increases up to 35.45% in the absence of the electromagnetic field. Also, it was observed that the presence of electromagnetic field dramatically increases the oil recovery factor by 79.83 percent. The critical factor for such growth in recovery is the decrease in oil viscosity by almost 950 centipoise, which is due to the temperature increase and possible cracking of heavier components of oil into lighter components. In addition, the Interfacial Tension between oil and nanofluid decreases with increasing the nanoparticles concentration by almost 16 mN/m.

A review on synthesis of Cadmium and Manganese oxide nanoparticles with its vitro applications

Nanoparticles have a greater surface area and thus precise characteristics in the implementation and development of nano-specifically dimensioned materials. The Photocatalytic degradation properties of cadmium oxide (CdO) and manganese oxide (MnO) nanoparticles (NPs) vary significantly than those of standard products due to their large bandwidth and energy binding. These nanoparticles have potential applications in antibacterial, antioxidant, antimicrobial etc. these nanoparticles were produced using a number of ways such as sol-gel, co-precipitation, green synthesis, microwave etc.

Symmetric supercapacitors composed of ternary metal oxides (NiO/V2O5/MnO2) nanoribbon electrodes with high energy storage performance

Supercapacitors with improved specific capacitance, long cycling life, high power density and energy density are fabricated to close the gap between traditional and emerging energy storage. We develop interactive ternary metal oxides nano-ribbon electrodes used to assemble symmetric supercapacitor. The well-aligned vanadium oxide ribbon arrays act as the matrix, growing from nickel oxide/nickel substrate and then being grafted by manganese oxide nanoparticles. These tri-metallic oxides are formed in a cost-effective and green hydrothermal chemistry. The electrodes composed of ribbon arrays retain their crystallographic structure during charging and discharging processes, enabling steadiness at 83.6 % after 10,000 cycles. These as-prepared electrodes demonstrate a specific capacitance of 788 F g−1 at 5 mV s−1. The symmetrical supercapacitors are assembled using triple component electrodes, achieving a high energy density of 138 W h kg−1 at a power density of 450 W kg−1. These binderless single-cell devices are reported with a simplified design showing 10–20 times higher energy density in comparison with reported results of the V2O5-MnO2 system. The nanografting results in reactive interfaces with interpenetrating channels for efficient ion transport and electron conduction. The advances to design nanostructured supercapacitor materials are based on these heterojunction arrays to enhance their supercapacitive performances.

Nickel decorated manganese oxynitride over graphene nanosheets as highly efficient visible light driven photocatalysts for acetylsalicylic acid degradation

In this work, we prepared nanocomposites of nickel-decorated manganese oxynitride on graphene nanosheets and demonstrated them as photocatalysts for degradation of acetylsalicylic acid (ASA). The catalyst exhibited a high degradation efficiency over ASA under visible light irradiation and an excellent structural stability after multiple uses. Compared to manganese oxide (MnO) and manganese oxynitride (MnON) nanoparticles, larger specific surface area and smaller band gap were observed for the nanocomposite accounting for the enhanced photocatalytic efficiency. Besides the compositional effect of the catalyst, we also examined the influence of various experimental parameters on the degradation of ASA such as initial concentration, catalyst dose, initial pH and additives. The best performance was obtained for the nanocomposite when the catalyst dose was 10 mg/mL and the initial pH 3. Detection of intermediates during photocatalysis showed that ASA undergoes hydroxylation, demethylation, aromatization, ring opening, and finally complete mineralization into CO2 and H2O by reactive species. For practical applications as a photocatalyst, cytotoxicity of the nanocomposite was also evaluated, which revealed its insignificant impact on the cell viability. These results suggest the nanocomposite of nickel-decorated manganese oxynitride on graphene nanosheets as a promising photocatalyst for the remediation of ASA-contaminated water.

Heterologous expression and biophysical characterization of a mesophilic tannase following manganese nanoparticle immobilization

In the current study, we analyzed the efficacy of manganese oxide nanoparticle (MnNP)-water dispersion as an immobilization matrix for bacterial tannase. The tannase-secreting Bacillus subtilis strain NJKL.tan.2 obtained from tannery effluent soil was subsequently purified and cloned in pET20b vector. The activity of MnNP-tan (tannase activated by manganese nanoparticles) was 1.51- and 3.5-fold higher at 20 °C and 80 °C, respectively, compared with the free enzyme. MnNP-tan decreased Km by 41.66 % and 3-fold, whereas free tannase showed two-fold and six-fold improvement in Kcat at 37 °C and 80 °C, respectively. MnNP-tan showed an increase in (half-life)t1/2and Ed by 13-fold and 50.05 units, respectively, at 80 °C, in contrast to the native enzyme. MnNP-tan retained its residual activity by 78.2 % at 37 °C and 34.24 % at 80 °C after 180 min of incubation when compared with untreated set. MnNP-tan retained 51 % of its activity after 120 days with the native enzyme losing ∼50 % functionality following 40 days of incubation. The MnNP-mediated tannase immobilization technique is being reported for the first time. The technique has numerous advantages due to the use of MnNP as a potential matrix for biomolecule immobilization, which can be further extended to immobilize other biocatalysts used in agro-industrial and lab-based applications.

Fabrication of Versatile Hollow Metal-Organic Framework Nanoplatforms for Folate-Targeted and Combined Cancer Imaging and Therapy.

Metal-organic frameworks (MOFs) have received extensive attention in the field of biomedicine, particularly serving as multifunctional theranostic nanoplatforms by integrating chemodrugs, imaging agents, and targeting agents. Herein, we report a facile strategy for the fabrication of a hollow and monodisperse MOF (denoted hMIL-88B(Fe)@ZIF-8) consisting of ZIF-8 nanoparticles loaded on the external shell of hollow MIL-88B(Fe). In particular, the hybrid hollow MOF was constructed by partially etching spindlelike MIL-88B(Fe) nanoparticles with 2-methylimidazole in the presence of zinc ions. The obtained hMIL-88B(Fe)@ZIF-8 was then used as a drug/cargo delivery vehicle for loading doxorubicin (DOX), manganese oxide (MnOx) nanoparticles, and folic acid (FA), forming a multifunctional nanoplatform (denoted hM@ZMDF). Importantly, the resulting hM@ZMDF exhibited a specific targeting property for the FA receptor-overexpressed cancer cells (MCF-7 and HepG-2 cells) and then it unloaded DOX and Fe3+ in the tumor microenvironment. Consequently, DOX played dual roles as a chemotherapeutic drug and a fluorescent imaging agent. Also, the released Fe3+ could mediate the Fenton reaction and intracellularly generate toxic hydroxyl radicals in the presence of high glutathione in cancer cells. In addition, MnOx nanoparticles could participate in magnetic resonance imaging. Therefore, the versatile hM@ZMDF nanoplatforms have great potential for smart cancer therapy.

Application of manganese oxide nanoparticles synthesized via green route for improved performance of water-based drilling fluids

Application of manganese oxide nanoparticles synthesized via green route for improved performance of water-based drilling fluids

Application of Manganese Oxide (MnO) nanoparticles in multimodal molecular imaging and cancer therapy: A review

Contrast agents (CAs) play a critical role in high-resolution magnetic resonance imaging (MRI) applications to enhance the low intrinsic sensitivity of MRI. Manganese oxide nanoparticles (MnO) have gotten developing consideration as substitute spinâ��lattice (T1) MRI CAs as a result of the Gd-based CAs which are related with renal i¬�brosis as well as the inherent dark imaging characteristics of superparamagnetic iron oxide NPs. In this review, previous developments in the usage of MnO nanoparticles as MRI CAs for cancer theranostic applications such as developments in toxicological properties, distribution and tumor microenvironment (TME)-responsive biomaterials were reviewed. A literature search was accomplished to discover distributed research that elaborates the use of MnO in multimodal imaging and therapy. In the current study, the electronic search including PubMed/Medline, Embase, ProQuest, Scopus, Cochrane and Google Scholar was performed dependent on Mesh key words. CAs can significantly improve the imaging contrast among the lesions and normal tissues. In this study we generally concentrate on typical advancements of MnO nanoparticles about properties, bimodal or multimodal imaging, and therapy. Numerous researches have demonstrated MnO-based nanostructure produce considerable biocompatibility with the lack of cytotoxicity. Therefore, remarkable features improved photothermal therapy, chemotherapy and Chemodynamic therapy.

Highly dispersed MnO nanoparticles supported on N-doped rGO as an efficient oxygen reduction electrocatalyst via high-temperature pyrolysis

Transition metal-based compounds, due to their excellent ORR catalytic performance under alkaline condition, have recently emerged as one of the most promising alternatives to noble metal-based ORR catalysts. It is worth noting that manganese oxide can take an unique advantage for decomposition of intermediate adsorption products H2O2 and can effectively reduce O2 to OH−. However, most research has focused on MnO2, while attention has rarely been paid to MnO catalysts. In addition, under high-temperature pyrolysis condition, MnO is the most stable manganese oxide but MnO nanoparticles easily agglomerate. Hence, it is very difficult to obtain well-dispersed and small-sized MnO nanoparticles. Herein, on the basis of pre-synthesizing uniformly distributed manganese complexes on the reduced graphene oxide (rGO), we innovatively prepare highly dispersed and small-sized MnO nanoparticles (~3.94 nm) via high-temperature pyrolysis, which are uniformly anchored on N-doped reduced graphene oxide (NrGO) as an efficient oxygen reduction electrocatalyst. The as-obtained MnO/NrGO (1050 °C) electrocatalyst achieves satisfactory onset potential (0.942 V) and half-wave potential (0.820 V) under alkaline condition. And the limiting current density is 4.17 mA cm−2, which is very close to that of Pt/C (20 wt%, JM). Meanwhile, MnO/NrGO (1050 °C) catalyst presents superior longstanding durability and methanol resistance than Pt/C (JM). This work indicates that high-temperature pyrolysis can improve the purity of manganese oxide, simultaneously the defects of NrGO can reduce particle size of MnO nanoparticles, which are greatly beneficial to improve ORR performance. This work provides a new idea for research of MnO catalysts for ORR in the future.

Synthesis, characterization and electrochemical sensors application of MnO2 nanoparticles

The prepared MnO2 nanoparticles were characterized through electronic spectroscopy. The band gap value of nanoparticles is 3.12 eV. The stretching vibration band of nanoparticles of MnO2 at 631 cm−1 can be assigned to Mn–O. The manganese oxide nano flower–like structure, proved through atomic force microscopy (AFM) photographic studies. The MnO2 morphology was confirmed uniform coating on the electrode surface. Glassy carbon electrode (GCE) was modified with manganese oxide nanoparticles to enhance the electrocatalytic activity of the redox behavior of ascorbic acid. The oxide nano flower modified electrode is used as fresh voltammetric determination of ascorbic acid. The results of voltammetric behavior are satisfactory in the electro oxidation of ascorbic acid, and exhibit considerable improvement compared to glassy carbon electrode. Under the optimized experimental conditions, the modified electrode exhibit better linear dynamic range from 50 μg/L to 500 μg/L with lower limit of detection 30 μg/L for the stripping voltammetric determination of ascorbic acid. The real sample solution of ascorbic acid was successfully applied for accurate determination of trace amounts on nanomaterials modified electrode.

Applications and Biological Activity of Nanoparticles of Manganese and Manganese Oxides in In Vitro and In Vivo Models.

The expanding applications of nanotechnology seem to be a response to many technological, environmental, and medical challenges. The unique properties of nanoparticles allow for developing new technologies and therapies. Among many investigated compounds is manganese and its oxides, which in the form of nanoparticles, could be a promising alternative for gadolinium-based contrast agents used in diagnostic imaging. Manganese, which is essential for living organisms as an enzyme cofactor, under excessive exposure—for example, due to water contamination or as an occupational hazard for welders—can lead to neurological disorders, including manganism—a condition similar to Parkinson’s disease. This review attempts to summarise the available literature data on the potential applications of manganese and manganese oxide nanoparticles and their biological activity. Some of the published studies, both in vitro and in vivo, show negative effects of exposure to manganese, mainly on the nervous system, whereas other data suggest that it is possible to develop functionalised nanoparticles with negligible toxicity and novel promising properties.