Porous Manganese Research Articles

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.

One-pot hydrothermal synthesis of hierarchical porous manganese silicate microspheres as excellent Fenton-like catalysts for organic dyes degradation

One-pot hydrothermal synthesis of hierarchical porous manganese silicate microspheres as excellent Fenton-like catalysts for organic dyes degradation

Compact and porous 3D MnO2/holey graphene films for high areal and volumetric performance in supercapacitors with high-thick electrodes

Most manganese oxide-based electrodes used for energy-storage applications suffer from poor ion and electron transport, particularly at high mass loadings and with thick electrodes. To counter this issue, 3D electrodes were developed; however, enhancing their areal and volumetric performance at high mass loadings is still a challenge. In this study, highly compact and 3D porous manganese dioxide and holey reduced graphene oxide (3D MnO2/HRGO) composite films were developed to ensure a high performance in supercapacitors at electrode thicknesses greater than 100 µm. The thick composite films were fabricated by the self-limiting deposition of MnO2 on 3D HRGO hydrogel scaffolds followed by capillary evaporation-induced drying. The 3D MnO2/HRGO electrodes optimized at a thickness of 216 μm showed outstanding specific areal and volumetric capacitances of 2.3 F cm−2 and 108.0 F cm−3 at 1 mA cm−2 and an impressive rate capability with a capacitance retention of 72.2% in the range of 1–40 mA cm−2. Furthermore, supercapacitors assembled with the 3D MnO2/HRGO electrodes with high mass loadings exhibited impressively high areal and volumetric energy densities of 149.7 μWh cm−2 and 2.8 mWh cm−3, respectively.

Porous manganese dioxide nanosheets on modified graphite felt for cathodes in high-capacity flexible Zinc-MnO2 batteries

Modified graphite felt (MGF) is a flexible substrate with many advantages and a simple one-step method involving HNO3 is designed to activate graphite felt by increasing the amount of oxygen-containing functional groups and mesopores. Owing to the etching effect, excellent hydrophilicity beneficial to loading of α-MnO2 is achieved to facilitate the formation of MnO2/MGF. The MnO2/MGF structure serves as the cathode in a flexible Zn//MnO2 battery which also consists of a cross-linked polyacrylamide hydrogel as the electrolyte and separator and a Zn flake as the anode. The flexible Zn–MnO2 battery has excellent energy storage behaviors and cycling durability such as a high areal capacity of 1.26 mA h cm−2 at 4 mA cm−2 as well as capacity retention of 99.8% over 1000 cycles. Furthermore, the battery provides a remarkable energy density of 1.82 mW h cm−2 at a power density of 3.7 mW cm−2. The modification strategy and materials have large potential in wearable and flexible devices.

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

Particle-size controlled porous nano-flowers constructing 3D hierarchical mesoporous manganese dioxide: Template-free formation and capacitive performance

Manganese dioxide porous nanoflowers are deemed as a potential supercapacitor electrode material due to its high surface-to-bulk ratio and abundant pore. In this paper, hierarchical porous manganese dioxide (MnO2) self-assembled by particle-size controlled porous nanoflowers with specific surface areas of > 300 m2 g−1 are prepared at room temperature by a simple template-free approach. The formation of porous nanoflowers as well as their particle sizes are found to be determined by the nucleation concentration in initial reaction. And investigation on the electrochemical performance and microstructures demonstrates that the specific capacitance of mesoporous MnO2 with similar crystallizations and morphologies is mainly determined by their specific surface areas (SSAs). And sample with average particle size of 60~80 nm as well as SSA of 380 m2 g−1 and a pore volume of 1.97cc g−1 exhibits the best electrochemical performance, a high specific capacitance of 245 F g−1 with excellent cycling stability of 99.1% after 5000 cycles at 5 A g−1 in 1 M aqueous Na2SO4, due to its well-defined morphology with proper particle size, larger specific surface areas (SSA) and higher pore volume.

Freezing-induced hierarchical porous manganese dioxide with excellent humidity tolerance for indoor formaldehyde removal

The K-Birnessite type MnO2 was recognized to be a promising material to remove indoor low-level formaldehyde at room temperature. However, moisture was considered to significantly affect the activity of MnO2 for working durably in the complex indoor environment. Here, we prepared a hierarchical porous δ-MnO2 with modest moisture adsorption–desorption content. The formaldehyde removal efficiency exceeds 90% for 200 h test at high gas-hourly space velocity (GHSV: 600 L·g−1·h−1) in both high and low humidity environments, indicating an excellent humidity tolerance. This work provides a meaningful long lifetime catalyst for using in an indoor environment.

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.

Oxidative degradation of sulfamethoxazole antibiotic catalyzed by porous magnetic manganese ferrite nanoparticles: mechanism and by-products identification

Magnetic porous manganese ferrite nanoparticles (MnxFe3-xO4) with diverse ingredient Mn/Fe mole ratios were synthesized to degrade sulfamethoxazole (SMX) antibiotic residues involving peroxymonosulfate (PMS) dissociation to produce free radical SO4•−, •OH and singlet oxygen 1O2 in the absence of heat and light. With the increase in proportion of manganese, the degradation efficiency of SMX increased from 19 to 70% in 30 min. The removal efficiency of SMX increased following the concentration increase of PMS (from 1 ~ 10 mM). After 60 min, the total organic carbon went down by 20%, and the concentration of NH4+ and NO3− accumulated obviously simultaneously. EPR study and chemical probe method, depending on scavenging revealed that SO4•−, •OH and 1O2 were generated and contributed to the degradation system. Based on the capture of eleven decomposition by-products by LC/MS, two different degradation pathways of SMX were determined, mainly consisting of cleavage of the S–N bond, hydroxylation of benzene and heterocyclic ring, oxidation of amino group and ring-opening cleavage processes. The nanoparticle reuse tests showed that the porous magnetic manganese ferrite nanoparticles could still maintain a high degradation efficiency after five oxidative degradation reactions. The magnetic porous manganese ferrite nanocrystals could activate the PMS to oxidize SMX antibiotic residue without additional energy.

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.

Manganese-Based Nanoactivator Optimizes Cancer Immunotherapy via Enhancing Innate Immunity.

Cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) are essential components of the innate immune sensors to cytosolic DNA and elicit type I interferon (IFN). Recent studies have revealed that manganese (Mn) can enhance cGAS and STING activation to viral infection. However, the role of Mn in antitumor immunity has not been explored. Here, we designed a nanoactivator, which can induce the presence of DNA in cytoplasm and simultaneously elevate Mn2+ accumulation within tumor cells. In detail, amorphous porous manganese phosphate (APMP) NPs that are highly responsive to tumor microenvironment were employed to construct doxorubicin (DOX)-loaded and phospholipid (PL)-coated hybrid nanoparticles (PL/APMP-DOX NPs). PL/APMP-DOX NPs were stably maintained during systemic circulation, but triggered to release DOX for inducing DNA damage and Mn2+ to augment cGAS/STING activity. We found that PL/APMP-DOX NPs with superior tumor-targeting capacity boosted dendritic cell maturation and increased cytotoxic T lymphocyte infiltration as well as natural killer cell recruitment into the tumor site. Furthermore, the NPs increased production of type I IFN and secretion of pro-inflammatory cytokines (for example, TNF-α and IL-6). Consequently, PL/APMP-DOX NPs exhibited excellent antitumor efficacy and prolonged the lifespan of the tumor-bearing mice. Collectively, we developed a PL-decorated Mn-based hybrid nanoactivator to intensify immune activation and that might provide therapeutic potential for caner immunotherapy.

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.

Metal–organic framework-derived MnO/CoMn2O4@N–C nanorods with nanoparticle interstitial decoration in core@shell structure as improved bifunctional electrocatalytic cathodes for Li–O2 batteries

Core@shell-structured, hierarchically porous manganese oxide/cobalt manganite@nitrogen-doped carbon (MnO/CoMn2O4@N–C) nanorods with interstitially decorated CoMn2O4 nanoparticles are synthesized via one-step carbonization of metal–organic framework (MOF)-coated α˗manganese oxide (α-MnO2@ZIF-67) nanorods and are evaluated as bifunctional electrocatalytic cathodes for Li–O2 batteries (LOBs) to improve the bifunctionality, specific discharge capacity, and cyclability of α˗MnO2 nanorod cathode-based LOBs. The MnO/CoMn2O4@N–C nanorods feature a MnO nanorod core with CoMn2O4 nanoparticle interstitial decoration, both coated by an N–C conductive shell. The MnO core renders Mn active sites and oxygen vacancies, while the CoMn2O4 interstitial decoration gives additional Mn, Co active sites, thereby enhancing bifunctional electrocatalytic ORR–OER. The N–C shell increases electronic conductivity, hierarchical porosity, specific surface area, and protects the core and interstitial decoration against lithium peroxide (Li2O2) passivation. The improved structural features allow the MnO/CoMn2O4@N–C nanorod cathode-based LOB cells to exhibit superior full specific discharge capacity of 8,625 mAh·g−1 and cyclability of 48 discharge–charge cycles at 200 mA·g−1 specific current and 2000 mAhg−1 limited specific discharge capacity compared to their α˗MnO2 nanorod counterparts. An ORR–OER mechanism is proposed to describe the interesting formation of particle- and film-type Li2O2 deposits at different cycles for the MnO/CoMn2O4@N–C nanorod cathodes. Such MOF-derived, interstitial nanoparticle-decorated nanoarchitectures can lead to high-performance tunable bifunctional electrocatalysts.

Hierarchical Porous Manganese- and Nitrogen-Codoped Carbon Nanosheets Derived from Surface Modified Biomass as Efficient Oxygen Reduction Catalysts for Al-Air Batteries

Oxygen reduction reaction (ORR) is essential for metal-air batteries and fuel cells, and it is urgent to develop non-precious metal catalysts with low cost and high performance for ORR. Here we propose a new general strategy for preparing hieratical porous manganese- and nitrogen-codoped carbon (Mn–N–C) derived from low cost biomass. This strategy demonstrates that pre-oxidation of the biomass with an optimized temperature plays an essential role in forming the unique structure of Mn–N–C due to the modification of surface functional groups on biomass. The resultant Mn–N–C displays superior ORR performance in both alkaline and neutral electrolytes, which is comparable or even higher than that of the commercial Pt/C catalyst. The superior electrocatalytic performance is ascribed to the intrinsically efficient Mn-Nx active sites and the high surface area together with the hieratical pores exposing more active sites, which is also confirmed by the density functional theory calculation. Furthermore, the Al-air battery based on the Mn–N–C cathode shows a high working voltage and maximum power density, demonstrating promising potential for practical application. This approach provides a new insight for low-cost and high performance electrocatalysts for metal-air 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.

A novel ultralight 3D-Mn(OH)4 porous material for heavy metal ions removal from water

Three-dimensional (3D) metal oxides, consisting of a simple nanostructure, have become the key to numerous environmental remediation technologies owing to their unique properties. Herein, a novel ultralight (0.0834 g/cm3) 3D manganese(IV) hydroxide (Mn(OH)4) material without volume shrinkage was exploited for the first time. The 3D-Mn(OH)4, with a porous structure composed of cross-linked ultra-long nanowires was fabricated through a mild and cost-effective hydrothermal treatment followed by a freeze-drying process. The excellent removal performance for low concentration toxic metal ions of 3D-Mn(OH)4 was ascribed to its high specific surface area, 3D porous structure, and abundant hydroxyl groups on the surface. Experimental data show that the maximum Cd(II), Co(II), and Cu(II) ions adsorption capacities have been demonstrated to be 107.75, 85.48, and 102.45 mg/g, respectively. Importantly, the used 3D-Mn(OH)4 demonstrated an excellent regeneration performance. To account for the mechanisms that affect the adsorption properties, a systematic study was carried out. These findings provide the possibility to expand the use of a novel ultralight 3D-Mn(OH)4 nanomaterial for application in the environmental sciences. It is believed that our research strategy could be extended to fabricate other three-dimensional porous manganese oxides with great promise for various applications.