Porous Manganese Oxide Research Articles

Waste to treasure: porous manganese oxides derived from the waste liquid for heavy metal ion adsorption

Waste to treasure: porous manganese oxides derived from the waste liquid for heavy metal ion adsorption

Mn-MOF derived N-doped MnOx@carbon heterogeneous catalysts for Vis-light, S2O82[sbnd], HSO5[sbnd], Vis/S2O82[sbnd], and Vis/HSO5[sbnd]-induced degradation of metronidazole: Kinetics and mechanistic study

Manganese oxide-based nanostructures have demonstrated remarkable potential for reactive radical generation to treat wastewater by activating persulfate (PS) and peroxymonosulfate (PMS) in the presence of visible-light irradiation. Herein, we report a facile strategy to synthesize nitrogen-doped porous MnOx@Carbon nanostructures by annealing Mn-based MOF at different temperatures and employed for the degradation of MTZ under Vis-light, PS, PMS, Vis/PS, and Vis/PMS systems. A significant catalytic synergy was found in the MnO-I/Vis/PMS system. Owing to the rational coordination of nitrogen-enriched porous manganese oxide embedded carbon, high surface area (179.6 m2/g), and surface-exposed abundant active sites, the composite named MnO-I exhibited excellent catalytic performance in all the studied processes. The carbonization process induces a polarization difference between Mn-N co-ordination, resulting in the carbon becoming an electron-deficient core and manganese an electron-rich center, thus providing more Mn (II/III) for PMS activation. The degradation study showed that 99 % removal of MTZ was achieved within 40 min, with a rate constant of 0.099 min−1, in the MnO-I/Vis/PMS system. Trapping experiments and EPR detection demonstrated that SO4•−, OH• and 1O2 radicals were the major species involved in the degradation process. Besides, the degradation pathway and impact of operational parameters, i.e., catalyst dosage, PMS concentration, initial pH, MTZ concentration, co-existing anions, and humic acid, on the removal of MTZ were also explored.

Porous Mn2O3 nanorods-based electrode for high-performance electrochemical supercapacitor

In this research, we introduce an effective electrode material, i.e. porous manganese oxide (Mn2O3) nanorods (NRs) prepared by simple hydrothermal process, designed for use in electrochemical supercapacitors. XRD analysis unequivocally confirms that the Mn2O3 NRs possess a pure cubic crystalline structure with an Ia3 space group, indicating the high degree of crystallinity and phase purity. Morphological examinations confirmed that the Mn2O3 NRs display a distinct rod-like structure, featuring an average size of around 30 nm, underscoring their nanostructured characteristics. The electrochemical performance of the synthesized Mn2O3 NRs as electrodes for supercapacitors was thoroughly examined, resulting in an impressive specific capacitance of 483 F/g at a scan rate of 10 mV/s. Electrochemical impedance spectroscopy (EIS) analysis was carried out to assess the effective series resistance (ESR), revealing a minimal resistance value of 3.2 Ω, highlighting excellent charge transfer kinetics. Mn2O3 NRs electrode displayed exceptional capacitance retention even after undergoing 500 charge–discharge cycles at a high current density of 5 A/g, indicating their remarkable chemical stability as an electrode material. This study introduces a promising and scalable approach for the development of high-performance supercapacitors, with Mn2O3 NRs as a critical component, and offers valuable insights into the design and engineering of advanced energy storage devices.

Synthesis and catalytic application of nanostructured metal oxides and phosphates.

The design and development of new high-performance catalysts is one of the most important and challenging issues to achieve sustainable chemical and energy production. This Feature Article describes the synthesis of nanostructured metal oxides and phosphates mainly based on earth-abundant metals and their thermocatalytic application to selective oxidation and acid-base reactions. A simple and versatile methodology for the control of nanostructures based on crystalline complex oxides and phosphates with diverse structures and compositions is proposed as another approach to catalyst design. Herein, two unique and verstile methods for the synthesis of metal oxide and phosphate nanostructures are introduced; an amino acid-aided method for metal oxides and phosphates and a precursor crystallization method for porous manganese oxides. Nanomaterials based on perovskite oxides, manganese oxides, and metal phosphates can function as effective heterogeneous catalysts for selective aerobic oxidation, biomass conversion, direct methane conversion, one-pot synthesis, acid-base reactions, and water electrolysis. Furthermore, the structure-activity relationship is clarified based on experimental and computational approaches, and the influence of oxygen vacancy formation, concerted activation of molecules, and the redox/acid-base properties of the outermost surface are discussed. The proposed methodology for nanostructure control would be useful not only for the design and understanding of the complexity of metal oxide catalysts, but also for the development of innovative catalysts.

A new magnetic heterogeneous catalyst for fast degradation of rhodamine B by peroxymonosulfate oxidation: Monodisperse-porous and Fe3O4 incorporated manganese oxide microspheres

A new synthetic method, “staged shape templating decomposition” suitable for transition or rare-earth metal oxide microspheres was developed for obtaining magnetic, uniform and porous manganese oxide (MagMnOx) microspheres. The microspheres 4.7 μm in size were obtained with a specific surface area of 45.5 m2 g−1. Fe3O4, Mn5O8, MnO2 and Mn2O3 phases were shown by X-ray diffraction spectroscopy. Mn2+, Mn3+ and Mn4+ states were observed on the surface by X-ray photoelectron spectroscopy. Catalase-like and oxidase-like activities of MagMnOx microspheres were explained by coexistence of Mn and Fe crystallites in a mesoporous structure with a sufficiently large surface area and a particle interior with large mesopores facilitating substrate diffusion. The maximum substate consumption rates for catalase-like and peroxidase-like activities were determined as 15.6 mM/min and 20.3 μM/min, respectively. By considering their ROS generation ability, MagMnOx microspheres were evaluated as a heterogeneous catalyst for rhodamine B (Rh B) removal via peroxymonosulfate (PMS) activation. Rh B was removed in the periods shorter than 15 min via chemical degradation with a limited physical adsorption. Superoxide anion (O2−●) and singlet oxygen (1O2●) radicals generated by MagMnOx-PMS system were responsible for degradation of Rh B. The highest apparent first order rate constant for Rh B degradation was calculated as 0.5771 min−1. The apparent first order rate constant increased with increasing MagMnOx and PMS concentrations and decreasing initial Rh B concentration. Rh B was almost completely removed in each of five recycling runs and only lower than 1.5 % w/w of Fe and Mn contents of MagMnOx microspheres were leached over five recycling runs. The catalyst with large particle size, resistant to agglomeration exhibited high removal rate, low dye adsorption, high magnetization, and high reusability for Rh B removal via peroxymonosulfate activation.

Synthesis and mechanism of MoS2 and graphene oxide insertion in porous multi metal ion modified MnO2 nanorods for dye degradation

Layered structure transition metal chalcogenide compound’s such as Molybdenum sulfide (MoS2) deposition in micro/meso porous architecture of MnO2 could provide hybrid interesting features. Multivalent MnO2 is an attractive low cost and toxic free catalytic material for oxidation reaction and electrochemical applications. Non-ionic surfactant implication in mesoporous metal ion modified MnO2 by deposition of metal chalcogenide is an effective composite for dye degradation applications. The low-cost pre-cursor makes it attractive for large-scale production at industrial scale. Hence, in the present study deals with exploit the mechanism of metal chalcogenide and graphene oxide insertion in porous manganese oxide matrix. The as prepared l surface properties of the Nickel and cobalt doped manganese oxide/MoS2 composite catalyst have shown effective congo red dye degradation activity. The complete color disappearance appeared after interaction with the composite catalyst.

SILD synthesis of porous manganese oxide nanocoatings as electroactive materials for pseudocapacitors

SILD synthesis of porous manganese oxide nanocoatings as electroactive materials for pseudocapacitors

Mesoporous Manganese Oxides with High-Valent Mn Species and Disordered Local Structures for Efficient Oxygen Electrocatalysis.

Active and nonprecious-metal bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital components of clean energy conversion devices such as regenerative fuel cells and rechargeable metal-air batteries. Porous manganese oxides (MnOx) are promising electrocatalyst candidates because of their high surface area and the abundance of Mn. MnOx catalysts exhibit various oxidation states and crystal structures, which critically affect their electrocatalytic activity. These effects remain elusive mainly because the synthesis of oxidation-state-controlled porous MnOx with similar structural properties is challenging. In this work, four different mesoporous manganese oxides (m-MnOx) were synthesized and used as model catalysts to investigate the effects of local structures and Mn valence states on the activity toward oxygen electrocatalysis. The following activity trends were observed: m-Mn2O3 > m-MnO2 > m-MnO > m-Mn3O4 for the ORR and m-MnO2 > m-Mn2O3 > m-MnO ≈ m-Mn3O4 for the OER. These activity trends suggest that high-valent Mn species (Mn(III) and Mn(IV)) with disordered atomic arrangements induced by nanostructuring significantly influence electrocatalysis. In situ X-ray absorption spectroscopy was used to analyze the changes in the oxidation states under the ORR and OER conditions, which showed the surface phase transformation and generation of active species during electrocatalysis.

Electrochemically embedded nickel oxide in a highly porous manganese oxide film with enhanced catalytic kinetics of the urea oxidation reaction

The use of well-dispersed nickel catalysts with atomic-scale sizes is an effective approach for maximizing catalytic activity and selectivity for the urea oxidation reaction (UOR). Herein, a porous ultrathin film of Birnessite-type manganese oxide is anodically deposited on a nickel substrate as a catalyst support. Some of the intercalated sodium ions are replaced by the dissolved nickel ions from the nickel substrate in the anodic process, forming manganese oxide with partially intercalated nickel ions (denoted MnO2). The amount of nickel species can be easily increased by cyclic voltammetry in the nickel sulfate electrolyte (denoted MnO2-Ni), without the relatively time-consuming process of conventional ion exchange. Most of the embedded nickel species are catalytic Ni3+ ions, rendering MnO2-Ni a favorable catalyst to boost the UOR. The cyclic voltammetry results reveal that Ni3+ catalysts, when inserted into the layer-structured manganese oxide, can increase the electroactive surface area for the adsorption of urea and increase the charge-transfer rate constant for the Ni3+/Ni2+ redox couple, leading to an improved catalytic rate constant of the UOR. A highly porous manganese oxide matrix provides many transport pathways for facilitating UOR kinetics. Electrochemical impedance spectroscopy shows that MnO2-Ni has lower direct and indirect UOR impedances than MnO2 and bare Ni electrodes, leading to a greater oxidation current and lower onset potential.

Sponge-like porous manganese(II, III) oxide as a coating for solvent-assisted solid-phase microextraction of polycyclic aromatic hydrocarbons followed by gas chromatography-mass spectrometry

A nanostructure sponge-like porous manganese(II, III) oxide was synthesized and applied as a new fiber coating for solvent-assisted solid-phase microextraction. The synthesized material was characterized via Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and N2 adsorption/desorption techniques. To investigate the extraction performance of the prepared material, direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry was used for the determination of the selected polycyclic aromatic hydrocarbons in wastewater samples. Three polycyclic aromatic hydrocarbons including 1-methylnaphthalene, anthracene, and pyrene were selected as model analytes. To maximize the sensitivity of the method, key experimental factors affecting the extraction efficiency of the analytes such as ionic strength, extraction solvent, stirring rate, extraction temperature and time, and desorption temperature and time were optimized. The applicability of the new coating material for the extraction of the selected analytes from wastewater samples was evaluated. Under the optimum conditions, detection limits between 0.7 and 1.5 ng L−1 were obtained for the model analytes. The linear dynamic range was 5.0–3.0 × 103 ng L−1 for all the analytes. Relative standard deviations were between 2 and 11%. In the case of real sample analysis, the extraction recoveries of the analytes were obtained in the range of 77–111%.

Benzil alkol oksidasyonu için heterojen katalizör olarak altın nanoparçacık immobilize edilmiş gözenekli manganez oksit mikroküreler

A heterogenous catalyst in the form of Au nanoparticles (Au NPs) immobilized porous manganese oxide (Mn5O8) microspheres was synthesized. The sol-gel templating method was used for the synthesis of Mn5O8 microspheres. The heterogenous catalyst showed good performance when compared with similar catalysts in the oxidation of benzyl alcohol. The heterogenous catalyst (Au@Mn5O8) obtained by the immobilization of Au NPs on Mn5O8 microspheres performed 99.4% of benzyl alcohol conversion and 100 % of benzaldehyde formation yield. Also the heterogenous catalyst showed a good stability and agglomeration resistance in the reusabilty experiments. Au@Mn5O8 microspheres could be reused up to 5 times without remarkable loss in the catalytic activity.

Fabrication of Ag@Ag2O-MnOx composite nanowires for high-efficient room-temperature removal of formaldehyde

Efficient removal of pollutant formaldehyde (HCHO) at room temperature using transition-metal oxides remains a huge challenge to date. Manganese oxide can oxidize formaldehyde, however, how to control the valence states of manganese is the key to further improve the removal efficiency. We have successfully prepared porous manganese oxide nanowires (MnOx NWs) with large surface area and multiple valence states of manganese using simple electrospinning followed by thermal calcination and potassium permanganate solution post-treatment (C/S process). The contents of trivalent and tetravalent manganese increased significantly after C/S process. Moreover, the composition of silver oxide coated silver nanowires (Ag@Ag2O NWs) is realized by assistance with oxygen plasma, which further enhanced high valence manganese. The formaldehyde removal efficiency by Ag@Ag2O–MnOx composite nanowires can reach 93.7%. The high-efficient catalytic activity is confirmed to attribute to the higher surface area of composite nanowires, the high-valence manganese and the silver oxide for oxidation of formaldehyde.

Ultra-sonication assisted metal chalcogenide modified mesoporous Nickel-cobalt doped manganese oxide nanocomposite fabrication for sono-catalytic dye degradation and mechanism insights

The present study is to demonstrate the molybdenum sulphide (MoS2) modified metal ion doped manganese oxide (MnO2) effect for sono-catalytic dye degradation application. The as-prepared additive (5% and 10% MoS2) modified Nickel-cobalt modified porous Manganese oxide (Ni─Co─MnO2) catalysts have shown complete dye discoloration and good sorption activity due to improved higher surface area values compared to undoped pristine manganese oxide. X-ray diffraction pattern confirms the formation of α-phase of MnO2 with tunnel structure formation due to present synthesis method. The thermal stability and structure-property relationship of prepared catalysts have studied by various physico-chemical methods. The thermal stability of the prepared catalysts have stable up to 500─600 °C with Mn2O3 phase and it is further transform into more stable Mn3O4 phase. The fascinating flaky morphology of MnO2 and nanofibers of MoS2 nanoparticle exfoliation into porous manganese oxide matrix, which is clearly examined by SEM and HR-TEM. The particle size and zeta potential values are described for their respective surface property alteration. The pristine Ni─Co─MnO2 and additive modified catalyst have exhibiting effective and complete degradation for Congo red (CR) dyes after modification by MoS2. The re-peated results are obtained for re-used catalyst for dye degradation in the sono-catalytic process. The sono-catalytic mechanism insights of cong red degradation in the presence of MoS2/Ni─Co─MnO2 catalyst have also been demonstrated. The cycle stability for dye degradation and reusability of the as-prepared catalysts show effective repeating activity up to 95%.

One-step synthesis of carbon incorporated 3D MnO2 nanorods as a highly efficient electrode material for pseudocapacitors

3D Porous manganese oxide nanorods (pMn-NRs) are produced via hydrothermal approach and utilized as an electrode material for pseudocapacitor. The pMn-NRs supported on carbon textile exhibit high pseudocapacitive charge storage in an aqueous electrolyte. Interestingly, the pMn-NRs electrode can operate up to a potential window of 1.0 V and exhibits admirable capacitance of 1243F g−1 at 1 A g−1 (approaching theoretical value) with superb cycling stability (98%) over 15,000 cycles.

Porous Manganese Oxide Networks as High-Capacity and High-Rate Anodes for Lithium-Ion Batteries

A mesoporous MnOx network (MMN) structure and MMN/C composites were prepared and evaluated as anodes for high-energy and high-rate lithium-ion batteries (LIB) in comparison to typical manganese oxide nanoparticle (MnNP) and graphite anodes, not only in a half-cell but also in a full-cell configuration (assembled with an NCM523, LiNi0.5Co0.2Mn0.3O2, cathode). With the mesoporous features of the MMN, the MMN/C exhibited a high capacity (approximately 720 mAh g−1 at 100 mA g−1) and an excellent cycling stability at low electrode resistance compared to the MnNP/C composite. The MMN/C composite also showed much greater rate responses than the graphite anode. Owing to the inherent high discharge (de-lithiation) voltage of the MMN/C than graphite as anodes, however, the MMN‖NCM523 full cell showed approximately 87.4% of the specific energy density of the Gr‖NCM523 at 0.2 C. At high current density above 0.2 C, the MMN‖NCM523 cell delivered much higher energy than the Gr‖NCM523 mainly due to the excellent rate capability of the MMN/C anode. Therefore, we have demonstrated that the stabilized and high-capacity MMN/C composite can be successfully employed as anodes in LIB cells for high-rate applications.

Controllable Preparation of Porous Manganese Oxides with Microwave Heating Using Carbothermal Reduction

Controllable Preparation of Porous Manganese Oxides with Microwave Heating Using Carbothermal Reduction

SYNTHESIS AND CHARACTERIZATION OF MoS2 –GRAPENE OXIDE ON Ni-Co-MnO2 NANOFIBER LIKE BINARY COMPOSITE FOR NICKEL FOAM BASED FLEXIBLE ELECTRODE FABRICATION

Nickel/cobalt co-doped porous manganese oxide(MnOx) is fabricated by feasible nonionic surfactant route followed by precipitation heat treatment method. The as prepared metal ion modified manganese oxide further impregnated via reducing graphene oxide and MoS2 nanoparticles by ultra-sonication assisted deposition method. The as prepared binary nanocomposite is characterized by XRD and HR-TEM for crystalline phase formation analysis and structure morphology determination. Binder free flexible electrode fabrication on nickel foam using MoS2/graphene modified Ni-Co-MnO2 have also been studied and it shows higher super capacitor performance like 1190 F/g in aqueous acidic conditions.

Catalytic activity of porous manganese oxides for benzene oxidation improved via citric acid solution combustion synthesis

Various manganese oxides (MnOx) prepared via citric acid solution combustion synthesis were applied for catalytic oxidation of benzene. The results showed the ratios of citric acid/manganese nitrate in synthesizing process positively affected the physicochemical properties of MnOx, e.g., BET (Brunauer-Emmett-Teller) surface area, porous structure, reducibility and so on, which were in close relationship with their catalytic performance. Of all the catalysts, the sample prepared at a citric acid/manganese nitrate ratio of 2:1 (C2M1) displayed the best catalytic activity with T90 (the temperature when 90% of benzene was catalytically oxidized) of 212℃. Further investigation showed that C2M1 was Mn2O3 with abundant nano-pores, the largest surface area and the proper ratio of surface Mn4+/Mn3+, resulting in preferable low-temperature reducibility and abundant surface active adsorbed oxygen species. The analysis results of the in-situ Fourier transform infrared spectroscopy (in-situ FTIR) revealed that the benzene was successively oxidized to phenolate, o-benzoquinone, small molecules (such as maleates, acetates, and vinyl), and finally transformed to CO2 and H2O.

Synthesis and electrochemical properties of coaxial-cable nanostructure carbon wrapped manganese oxide as anode for lithium ion batteries

A novel and effective carbon wrapped manganese oxide material with coaxial-cable structure was synthesized through two processes of hydrothermal method and calcination. Transmission electron microscopy discovered that the as-prepared material had a porous manganese oxide inside core with a diameter of about 100–600 nm and a graphite cable jacket with a thickness of about 20–100 nm. The results of the electrochemical measurements exhibited that the as-prepared material had great energy density, long cycling life and favorable charge-discharge capability when it was used as an anode material in lithium ion batteries. The results revealed that the carbon wrapped manganese oxide was an excellent candidate for the anode of lithium ion batteries.

Porous manganese oxides synthesized with natural products at room temperature: a superior humidity-tolerant catalyst for ozone decomposition

Porous cerium-doped manganese oxides have been facilely synthesized with dopamine and exhibit prominent activity and humidity tolerance for O3 decomposition.