Manganese Oxide Nanocomposite Research Articles

PREPARATION AND STRUCTURAL CHARACTERIZATION OF MoS2 NANOPARTICLE COATED GRAPHENE OXIDE/MANGANESE OXIDE COMPOSITE FOR ENERGY STORAGE APPLICATION

Nanoparticles of powder molybdenum sulphide (MoS2) are deposited on reduced graphene oxide-mesoporous manganese oxide nanocomposite which is represented as MoSGMn were prepared by feasible ultrasonic assisted deposition technique. The above prepared nanocomposite is further coated on Nickel foam substrate for direct application towards supercapacitor electrode fabrication. The detailed studies of thermal property and surface property such as thermal stability, surface structure and zeta potential measurements have been explained for all prepared nanocomposite samples. The thermal stability of as prepared sample stable upto 350 oC in oxygen atmosphere and negative zeta potential obtained for all prepared nanocomposite sample. The different amount of MoS2 nanoparticle (10mg -100 mg range) was utilized to study the effect of molybdenum sulphide addition on major mesoporous manganese oxide matrix. Increased quantity of MoS2 addition increase the electrochemical supercapacitance value of the nanocomposite coated nickel foam modified electrode.

Surface bound nanostructures of ternary r-GO / Mn3O4/V2O5 system for room temperature selectivity of hydrogen gas

Room temperature detection of highly sensitive Hydrogen (H2) gas sensing material preparation was taken as a major objective in this present work. Herein, a novel one pot hydrothermal method is proposed for the synthesis of ternary r-GO decorated Manganese oxide (Mn3O4) and Vanadium pentoxide (V2O5) nanocomposite. The significant electrical conductivity of r-GO plays an important role here to enhance the sensing property. Tunable band bending features of metal oxides over the r-GO surface makes the composite works at room temperature with high selectivity of H2. The optical, structural and morphological characteristics were analyzed by UV–Visible spectroscopy (UV–Vis), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray Photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), and High Resolution-Transmission Electron Microscope (HR-TEM). The sensing results reveals that the present nanocomposite is selectively sensitive towards H2 with sensitivity value of (175%) at room temperature with response time (82 s) and recovery time (92 s). To investigate the low detection limit gas concentration was varied in the range from 20 ppm to 50 ppm. The synergetic sensing performance and stability of this nanocomposite could be due to the formation of metal oxides with perspicuous nanostructures as heterojunction decorated over the r-GO stack layer.

Intelligent Protein-Coated Bismuth Sulfide and Manganese Oxide Nanocomposites by Biomineralization for Multimodal Imaging-Guided Enhanced Tumor Therapy

Radiotherapy (RT) has been used clinically to overcome cancer in recent decades. However, the abnormal tumor microenvironment (TME) featured with hypoxia, acidosis, and dense extracellular matrix is found to be related with the resistance of tumors to RT. Herein, intelligent bovine serum albumin (BSA)-coated Bi2S3 and MnO2 (Bi2S3-MnO2) nanocomposites synthesized by biomineralization are capable of modulating hypoxic TME effectively to enhance the efficacy of RT. After intravenous injection, the BSA-Bi2S3-MnO2 nanocomposites show efficient accumulation in tumor where endogenous H2O2 could be reacted with MnO2 to generate oxygen in-situ, leading to increased tumor oxygenation to overcome the hypoxia-associated resistance for RT. Moreover, the photothermal effect induced by BSA-Bi2S3-MnO2 nanocomposites further relieves the hypoxia in TME and finally synergistically improves RT effect. In this work, we present a simple strategy to fabricate intelligent therapeutic nanoparticles for improving therapeutic efficiency in cervical cancer.

Intelligent protein-coated bismuth sulfide and manganese oxide nanocomposites obtained by biomineralization for multimodal imaging-guided enhanced tumor therapy.

Radiotherapy (RT) has been used clinically to overcome cancer in recent decades. However, the abnormal tumor microenvironment (TME), involving hypoxia, acidosis and a dense extracellular matrix, is found to be related to the resistance of tumors to RT. Herein, intelligent bovine serum albumin (BSA)-coated Bi2S3 and MnO2 (Bi2S3-MnO2) nanocomposites synthesized via biomineralization are capable of modulating the hypoxic TME effectively to enhance the efficacy of RT. After intravenous injection, the BSA-Bi2S3-MnO2 nanocomposites show efficient accumulation in tumors, where endogenous H2O2 can react with MnO2 to generate oxygen in situ, leading to increased tumor oxygenation to overcome the hypoxia-associated resistance to RT. Moreover, the photothermal effect induced by the BSA-Bi2S3-MnO2 nanocomposites further relieves hypoxia in the TME and, finally, synergistically improves the effects of RT. In this work, we present a simple strategy to fabricate intelligent therapeutic nanoparticles to improve therapeutic efficiency towards cervical cancer.

Room temperature ferromagnetic behavior of manganese/manganese oxides nanocomposites

Three different manganese oxide nanocomposites such as Mn3O4, Mn5O8, and Mn2O3 along with metallic-Mn were synthesized via a single route depending on calcination temperature. Structural, electrical, and magnetic properties were assessed for the synthesized nanocomposites. The real and imaginary parts of dielectric constants decreased at the lower frequency and then remained constant at the higher frequency for all the three types of nanocomposites. The permeability of the nanocomposites also followed the same order. Mn/Mn5O8 nanorods showed strong ferromagnetic behavior at room temperature although Mn-nanoparticles and Mn5O8 are paramagnetic and antiferromagnetic in nature respectively.

Synthesis of MoS2 nanoparticle deposited graphene/mesoporous MnOx nanocomposite for high performance super capacitor application

The present study deal with the fabrication of low cost nanocomposite based electrodes based on Nickel foam binder free substrate for supercapacitor applications. The composition of nanocomposite is molybdenum sulphide nanoparticle/graphene coated on mesoporous manganese oxide. The first step is to involve the preparation of mesoporous manganese oxide by non-ionic surfactant assisted method. In the second stage is to deposit the reduced graphene on mesoporous manganese oxide in the presence of ultrasonic irradiation followed by addition of known quantity of commercial MoS2 nanopowder (particle size below 90 nm). The manganese oxide based nanocomposite is showing porous architecture with graphene sheet formation together with MoS2 nanoparticle deposition. N2 adsorption-desorption Isotherm curves for MoS2 nanoparticle (NP) modified graphene oxide/meso-MnO2 and pure meso-MnO2 displayed type IV isotherm with improved surface area values. The reduced graphene oxide (graphene) and MoS2 exist in the form of glassy flaky morphology as well as tubular/needle shapes are obtained after the deposition process in the final nanocomposite. The orderly arranged and anchored nano-sized mesoporous manganese oxide nanocomposites are showed increased specific capacitance (up to 527, 727 and 1160 F/g) and continuous cyclic stability.

New CuFe2O4/amorphous manganese oxide nanocomposites used as photocatalysts in photoelectrochemical water splitting

The utilization of visible light for the photoelectrochemical production of hydrogen gas from water is a scientific challenge. Water splitting for the production of hydrogen using copper-ferrite and amorphous manganese oxide composite can be efficient way. This is the first report which focuses on the electrophoretic deposition of solvothermally synthesized CuFe2O4/amorphous manganese oxide nanocomposites directly for photoelectrochemical water splitting under visible light. This study may provide a simple, cost-effective and environmentally benign method to promising photocatalyst and application for hydrogen evolution. Photoelectrochemical characterizations have showed that the photoelectrochemical water splitting performance increases when the mole ratio of amorphous manganese oxide increases. The photoelectrochemical measurements are conducted under visible light irradiation in 0.5 M Na2SO4 electrolyte. The best result of the photoelectrochemical hydrogen evolution activity (502.8 μmol in 90 min) is obtained when the mole ratio of the CuFe2O4/amorphous manganese oxide (1:4) is. It is observed that the as-obtained CuFe2O4/amorphous manganese oxide nanocomposites are quite efficient photocatalyst for photoelectrocatalytic hydrogen evolution under visible light irradiation.

Carbon Nanotubes–MnOx Nanocomposite as Support for Iron‐Based Catalysts for the Fischer–Tropsch Synthesis of Liquid Fuels

AbstractA facile one‐pot hydrothermal method is developed to synthesize a series of carbon nanotubes–manganese oxide nanocomposites (CNTs–MnOx) with different morphologies and Mn valence states. These nanocomposite materials are then utilized as catalyst supports in iron‐based Fischer–Tropsch synthesis (FTS) for the production of liquid fuels. Experimental results indicate that Fe/CNTs‐K‐190 (iron catalyst supported on the CNTs treated with KMnO4 at 190 °C) and Fe/CNTs‐KU‐190 (iron catalyst supported on the CNTs treated with KMnO4 and urea at 190 °C) display higher FTS activity than the Fe/CNTs‐K‐110 (iron catalyst supported on CNTs treated with KMnO4 at 110 °C) and Fe/CNTs‐KU‐110 (iron catalyst supported on CNTs treated with KMnO4 and urea at 110 °C). This might be due to the weak metal–support interaction and high MnO content, and the poorer stability than Fe/CNTs‐K‐110 and Fe/CNTs‐KU‐110 catalysts with nanosheet morphology might be related to the structural collapse of the nanocubes or nanorods due to MnO evolution during the FTS process. The CNTs–MnOx nanocomposite‐supported iron FTS catalysts in particular display unparalleled high C5+ selectivity (over 90 %) and very low CH4 selectivity (below 4.6 %). The unique CNTs–MnOx nanocomposites may open a new window for the understanding, design, synthesis, and optimization of iron catalysts toward high‐efficiency transport fuel production.

Adsorptive desulfurization of thiophene, benzothiophene and dibenzothiophene over activated carbon manganese oxide nanocomposite: with column system evaluation

Activated carbon was successfully treated with manganese oxide to further improve its surface properties for adsorptive desulfurization. The activated carbon-manganese oxide nanocomposite consisting 10% optimum metal loading showed significant adsorptive desulfurization efficiency. The textural properties (surface area 160.98 m2g−1, total pore volume 0.141 cm3g−1, and average pore diameter 9.27 nm) and surface chemistry of the as-synthesized activated carbon-manganese oxide adsorbent were crucial to the efficient desulfurization. The as-synthesized adsorbent displayed oxygen-containing functional groups and distinct pore structures that enabled rapid uptake of the refractory sulfur compounds within the initial 5 min of the adsorption process. The adsorption experimental data were best fitted to pseudo-second order kinetic and Temkin isotherm models. Adsorption capacities of 4.5 mg g−1, 5.7 mg g−1, and 11.4 mg g−1 were obtained for simultaneous adsorption of thiophene, benzothiophene, and dibenzothiophene on the as-synthesized adsorbent in a batch process, and the same trend was retained in the fixed bed model. The π-complexation and the direct sulfur-metal interaction could justify the greatest adsorption capacity for dibenzothiophene.

Spinel cobalt manganese oxide nano-composites grown hydrothermally on nanosheets for enhanced photocatalytic mineralization of Acid Black 1 textile dye: XRD, FTIR, FESEM, EDS and TOC studies

Spinel cobalt manganese oxide nano-composites were grown on nanosheets using acetate precursors in mono-ethylene glycol. Crystal structures and morphologies of nano-composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy and energy dispersive X-ray spectroscopy to characterize the element composition. Fourier transform infrared spectroscopy was used for structural characterization and UV–Vis diffuse reflectance spectra (UV–Vis DRS) for optical properties. XRD results showed tetragonal spinel cobalt manganese oxide (Co,Mn)(Co,Mn)2O4 and cubic spinel cobalt manganese oxide MnCo2O4.5 structural phases. The crystallite size calculated by the Scherrer’s equation was 17 nm. The morphological studies displayed the existence of 40–63 nm nano-powders grown on nanosheets with a good degree of crystallization. Optical properties of cobalt manganese oxide nano-composites exhibit absorbance edge, and the band gap calculated from UV–Vis DRS results was 1.78 eV. FTIR spectra indicated that hydroxyl and oxide groups were major active sites. The absorption bands observed at 656 and 568 cm−1 are related to stretching vibrations of Mn–O and Co–O, respectively. The photocatalytic activities of nano-composites for photocatalytic mineralization of Acid Black 1 textile dye showed an outstanding performance. Photocatalytic process yielded 91% total organic carbon removals within 2.5 h of irradiation. The enhanced photocatalytic activity was attributed to better charge separation of the photo-generated electron–hole pairs in nano-composite.

Synthesis and characterization of MnO2-decorated graphene for supercapacitors

We report the simple one-step synthesis of a reduced graphene oxide–manganese oxide (rGO-MnO2) nanocomposite using graphene oxide (GO) and KMnO4 in the presence of sulfuric acid. The crystal structure, morphology, thermal, pore size, and other physical properties of the rGO-MnO2 nanocomposite were systematically analyzed by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller analysis. XPS analysis confirmed the synthesis of exfoliated GO and rGO-MnO2 nanocomposite. The rGO-MnO2 nanocomposite exhibited a maximum specific capacitance, energy, and power density of 290Fg−1, 25.7Whkg−1, and 8008.7Wkg−1, respectively, in a 1M Na2SO4 electrolyte, and a high retention (87.5%) of capacitance after 5000 cycles. The enhanced electrochemical properties are caused by good contact between MnO2 nanorods and graphene nanosheets, and the higher conductive and capacitive behavior of graphene.

Brain-like cobalt manganese oxide nano-composites coated on glass surface for enhanced photocatalytic degradation of Black Nilusun: effect of precursors on properties

Brain-like cobalt manganese oxide nano-composites were effectively synthesized using co-precipitation processes. The effects of nitrate, sulfate and acetate of Co and Mn as precursors on structural, optical, thermal and morphological properties of cobalt manganese oxide nano-composites solid were studied by means of thermal analyses (TG–DTG), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy. The XRD results showed that the average particle size of cobalt manganese oxide nano-composites prepared from nitrate (MnCoNC-1), sulphate (MnCoNC-2) and acetate (MnCoNC-3) precursors were found to be 9, 12 and 13 nm respectively with MnCo2O4 and MnCo2O4.5 phases. The synthesised nanocomposites composed of spheres with brain-like structure are seen from FESEM results. The incorporation of cobalt into the manganese oxide structure is revealed by the distinctive FTIR transitions of Co–O–Mn vibrations. The characteristic band-gap energies of the different composites are estimated to be between 3.0 and 5.1 eV from UV reflection (DRS) spectra. Cobalt manganese oxide nano-composites coated on glass can effectively mineralize 92 % of azo textile dye within 3 h irradiation. The distinct properties and remarkable photocatalytical activities suggest the brain-type cobalt manganese oxide nano-composites are a promising material for enhanced photocatalytic degradation of Black Nilusun. The excellent photocatalytic activity may be due to the enhanced photo-induced charge separation brought on by the formation of coupling of two oxides in composite.

Rapid and highly selective removal of lead from water using graphene oxide-hydrated manganese oxide nanocomposites

To overcome the limits of graphene oxide (GO) as a novel sorbent for heavy metal removal (e.g., low sorption selectivity and difficulty in solid-liquid separation), a nanocomposite (HMO@GO) with excellent settling ability (<2min) was fabricated through in situ growing nanosized hydrated manganese oxide (HMO) (10.8±4.1nm) on GO. As a graphene-based adsorbent, HMO@GO exhibited fast sorption kinetics (<20min). Meanwhile, the introduced HMO endowed HMO@GO with outstanding sorption selectivity and capacity toward Pb(II) (>500mgg−1) in the presence of high-level competing Ca(II). Cyclic sorption batches showed that 1kg HMO@GO can treat at least 22m3 Pb(II)-laden synthetic industrial drainage (5mgL−1 Pb(II)) and 40m3 drinking water (0.5mgL−1 Pb(II)) to their corresponding limits (0.1mgL−1 for wastewater and 10μgL−1 for drinking water) enforced in China. Additionally, the exhausted HMO@GO can be effectively regenerated using 0.3 M HCl for repeated uses. The eminent performance of HMO@GO was attributed to its specific structure, that is, the abundant oxygen-containing groups on GO mediated the growth of highly dispersed HMO that preferably sequestrated Pb(II) through specific interaction, and the host GO offered the preconcentration of Pb(II) for enhanced sequestration through the Donnan membrane effect.

Fe3O4 and MnO2 assembled on halloysite nanotubes: A highly efficient solid-phase extractant for electrochemical detection of mercury(II) ions

In this study, a novel and simple magnetic electrochemical sensing protocol for the sensitive detection of Hg(II) in aqueous media was demonstrated. For this purpose, the halloysite nanotubes-iron oxide–manganese oxide nanocomposite (HNTs-Fe3O4–MnO2) was successfully synthesized for the first time. The synthesis process involves the deposition of Fe3O4 nanoparticles on the surface of HNTs using a simple chemical precipitation method, subsequent formation of wire-like MnO2 nanoparticles on the surface of HNTs-Fe3O4 composites by hydrothermal method with potassium permanganate (KMnO4) and ammonium persulfate ((NH4)2S2O8). The resulting HNTs-Fe3O4–MnO2 nanocomposite was suspended in mercury solution and then brought on the surface of a magnetic carbon paste electrode (MCPE). The amount of analyte was detected electrochemically by applying differential pulse voltammetry (DPV). The conditions of extraction and voltammetric determination were studied and optimized. The proposed method exhibited a linear relationship towards Hg(II) concentrations ranging from 0.5 to 150μgL−1. The detection limit achieved was 0.2μgL−1 (3Sb/m), which is lower than the US Environmental Protection Agency (EPA) standard (2μgL−1 for drinkable water). The proposed methodology was applied for quantification of Hg(II) in real water samples and good recoveries were obtained from 96.0 to 102.7%.

Magnetically separable magnetite–lithium manganese oxide nanocomposites as reusable lithium adsorbents in aqueous lithium resources

Spinel-structured lithium manganese oxides (LMOs) have generated considerable interest as adsorbents for the recovery of Li ions from aqueous Li resources such as brine, seawater, and concentrated seawater. However, practical applications are limited because powdered adsorbents are hard to handle and separate from a liquid. To overcome this problem, magnetically separable magnetite–LMO composite adsorbents (M–LMOs) were prepared by growing magnetite on LMO. The morphologies, crystal structures, chemical compositions, and magnetic properties of the prepared materials were characterized using various analytical techniques. The results confirmed that M–LMO had a spinel structure and contained two crystal phases. Li+ adsorption experiments were conducted using acid-treated M–LMO (M–HMO). The results confirmed that M–HMO was reusable and selectively adsorbed Li+ in the presence of Na+, K+, and Mg2+; the Li+ adsorption capacity was 6.84mg/g in LiCl buffer solution and 1.2mg/g in concentrated seawater, which is a much harsher condition than brine or seawater. M–HMO was conveniently separated from a liquid under an external magnetic field after Li+ adsorption. This is significantly different from conventional Li+ recovery systems such as granulation, foam formation, and membranization. These findings indicate that M–LMO could be used for Li+ recovery from aqueous Li resources and has good potential for practical applications.

Study on the Controlled Growth of Lanthanum Hydroxide and Manganese Oxide Nano Composite under the Presence of Cationic Surfactant

Lanthanum hydroxide and manganese oxide nano composite are synthesized by chemical routes. Physical characterization is done by TEM to look at the size and dispersion of the nano particles in the composite. Chemical characterization is done by X ray diffraction technique and FTIR to ascertain the attachment of the functionalities and bond stretching. Further thermal analysis is done by thermo gravimetric analysis to find the tendency of the thermal decomposition in the elevated temperatures range of 0-1000°C. Proper analysis and correlation of the various results obtained suggested the controlled growth of crystalline without agglomeration and good stability in the various temperature ranges of the composite.

Hydrothermal synthesis of hierarchical core–shell manganese oxide nanocomposites as efficient dye adsorbents for wastewater treatment

Hierarchical core–shell manganese oxide nanocomposites (Fe3O4@MnO2and Fe2O3@MnO2) are synthesizedviaa hydrothermal process and showed good adsorption capability for wide applications.

Pearl shaped highly sensitive Mn3O4 nanocomposite interface for biosensor applications

An electrochemical biosensor based on manganese oxide (Mn3O4) and chitosan (Cn) nanocomposite has been fabricated for fish freshness detection. The electrophoretic deposition of Mn3O4 nanoparticles (15–20nm) with Cn has changed their morphological arrangement leading to pearl shaped of Mn3O4–Cn nanocomposite on indium tin oxide substrate. Size and morphology of nanocomposite have been confirmed by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of electrochemical response reveal that this improved sensor has widest detection range of xanthine concentration from 1 to 500µM and excellent sensitivity of 1.46μAµM−1cm−2. The fabricated XOx/Mn3O4–Cn/ITO biosensor can detect as low as 1.31μM of xanthine and lower Km value of 0.018μM confirming its superior affinity towards the nanocomposite film.

High energy density asymmetric pseudocapacitors fabricated by graphene/carbon nanotube/MnO2 plus carbon nanotubes nanocomposites electrode

Abstract Novel graphene/carbon nanotubes (CNTs)/manganese oxide (MnO 2 ) nanocomposites plus CNTs (GMC + C) and graphene/CNTs hybrid (GC) thin-film electrodes are prepared by electrophoretic deposition (EPD). These nanocomposite electrodes exhibit high surface area and interconnected pore networks. The GMC + C nanocomposite electrode shows excellent specific capacitance of 964 F g −1 at 1 A g −1 , rate capability with the residual capacitance of 529 F g −1 at 500 mV s −1 , and fast Na + diffusion with intercalation value of 6.34 × 10 −7 cm 2 s −1 , and deintercalation value of 8.86 × 10 −7 cm 2 s −1 . Such excellent pseudocapacitive performances are attributed to low ion/electron transport resistances and short ion/electron diffusion lengths. Furthermore, novel aqueous electrolyte-based asymmetric pseudocapacitor having 1.8 V cell voltage is successfully fabricated using GMC + C nanocomposite as a cathode and GC nanocomposite as an anode. The optimized asymmetric pseudocapacitor possesses superior performance with a maximum energy density of record high 304 Wh kg −1 and retaining 56.2% of its initial specific energy density at the power density up to 242 kW kg −1 . In addition, the asymmetric cell configuration also shows excellent cycling stability with 89% specific capacitance maintained after 10,000 cycles. These results suggest that our designed asymmetric pseudocapacitors have a high potential for practical applications.

Bifunctional gold–manganese oxide nanocomposites: benign electrocatalysts toward water oxidation and oxygen reduction

Gold–manganese oxide nanocomposites exhibit efficient electrocatalytic activity toward water oxidation and oxygen reduction at a low overpotential and under neutral pH conditions.