Mn-based Metal-organic Frameworks Research Articles

Resonance energy transfer aided detection of nitroaromatics in aqueous medium by a luminescent Mn based metal-organic framework

A light brown needle-like crystal of Mn-based metal–organic framework (MOF); [Mn2.5(µ3-OH)(DTDB)2], (DTDB = 2,2′-dithiodibenzoate), compound 1, was synthesized using hydrothermal technique. Compound 1 was systematically characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and infrared spectroscopy (IR). Photoluminescence study of compound 1 in an aqueous medium showed intense blue emission centred at 395 nm upon excitation at 310 nm This emissive property of compound 1 was utilized for selective and sensitive detection of 2,4,6- trinitrophenol (TNP), 2,4- dinitrophenol (DNP) and 4-nitrophenol (NP) in the aqueous medium through luminescence quenching mechanism. As indicated by the good overlap of the absorption spectra of the analytes and the emission spectrum of the compound 1, and manifested as the reduction in luminescence lifetimes, it can be concluded that the resonance energy transfer is the most significant factor for the selective detection of aromatic nitro-phenol compounds. The resonance energy transfer requires the proximity of the donor and acceptor, which was achieved by the molecular level interactions between the ‘S’ atom of the DTDB ligand and phenolic –OH groups of the nitrophenols through non-covalent type interactions like hydrogen bonding and dipolar type interactions. Detection limits for TNP, DNP, and NP with the values of 208 ppb, 156 ppb, and 556 ppb, respectively, were obtained in an aqueous medium. The studies indicate that compound 1 could be helpful for detecting nitrophenol derivatives in water.

Exploring the Water Oxidation Catalytic Activity of a Mn-Based Magnetic Metal-Organic Framework: The Role of Proton Conductivity and Oxygen Evolution Reaction Overpotential.

The present work evaluates the water oxidation catalytic activity of a Mn-based metal-organic framework (MOF), which we envisioned to reduce the oxygen evolution reaction (OER) overpotential because of its high electrical conductivity, facilitated by solvent-encapsulated structural features. The presence of Mn centers induces interesting magnetic features in the MOF, which exhibits impressive cryogenic magnetic refrigeration with a ΔSM value of 29.94 J kg-1 K-1 for a field change of ΔH = 5T at 2.3 K. To the best of our knowledge, the ΔSM value of the current system ranked the highest position among the published examples. The crystal structure aligns perfectly with the thematic expectations and features as many as ten metal-coordinated water molecules, forming an extensive web of a hydrogen-bonded network while facing toward the porous channel filled with another set of much-anticipated entrapped lattice water molecules. Such structural features are expected to manifest high proton conductivity, and detailed investigation indeed yields the best value for the system at 1.57 × 10-4 S/cm at 95% humidity and 85 °C. In order to evaluate the thematic notion of a one-to-one relationship between OER and improved electrical conductivity, extensive electrocatalytic water splitting (WS) investigations were carried out. The final results show highly encouraging WS ability of the Mn-MOF, showing the electrocatalytic surface area value of the active species as 0.0686 F/g with a turnover frequency value of 0.043 [(mol. O2) (mol. Mn-MOF)-1 s-1]. Another fascinating aspect of the current communication is the excellent synergy observed between the experimental WS outcomes and the corresponding theoretical data calculated using density functional theory (DFT). Consequently, a plausible mechanism of the overall OER and the role of the Mn-MOF as a water oxidation catalyst, along with the importance of water molecules, have also been derived from the theoretical calculations using DFT.

Sugeno fuzzy inference system modeling and DFT calculations for the treatment of pesticide-laden water by newly developed arginine functionalized magnetic Mn-based metal organic framework.

The uncontrolled utilization of pesticides poses a significant risk to the environment and human health, making its management essential. In this regard, a new arginine functionalized magnetic Mn-based metal-organic framework (Arg@m-Mn-MOF) was fabricated and assessed for the removal of cypermethrin (CYP) and chlorpyrifos (CHL) from aqueous system. The Arg@m-Mn-MOF was characterized by scanning electron microscopy, energy dispersive X-ray, Fourier transform infrared spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller analysis. Various parameters were optimized in a series of batch experiments and the following conditions were found optimal: pH: 4 and 5, contact time: 20min, adsorbent dosage: 0.6 and 0.8g L-1 with initial concentration: 10mg L-1 and temperature: 298K for CYP and CHL, respectively. The composite attained a maximum removal capacity of 44.84 and 71.42mgg-1 for CYP and CHL, respectively. The elucidated data was strongly fitted to the pseudo-second-order model of kinetics (R2 > 0.98) and Langmuir isotherm (R2 > 0.98). Based upon 350 experimental datasets obtained from batch studies and interpolated data, the adsorption capacity of the adsorbent was elucidated with R2 > 0.97 (CHL) and > 0.91 (CYP). The adsorption energy (- 11.67kcalmol-1) calculated by Gaussian software suggests a good interaction between arginine and CHL through H-bonding. The present study's findings suggested the prepared Arg@m-Mn-MOF as a promising adsorbent for the efficient removal of pesticides from agriculture runoff.

A significantly fluorescence-enhanced probe for Al3+ based on a new AIEgens Mn-based metal-organic frameworks

Photoluminescence chemical sensors based on metal-organic frameworks have excellent applications in detecting heavy metal ions in water systems due to their advantages such as good sensitivity and short response time. Herein, a novel AIEgens Mn-based LMOF, [Mn(tipe)4(bpdc)2]n (LMOF-1) (tipe = 1,1,2,2-tetrakis(4-(1H-imidazol-1-yl)phenyl)ethene, bpdc = [1,1′-biphenyl]-4,4′-dicarboxylic acid), was synthesized by solvothermal method, and characterized by X-ray single crystal diffraction, elemental analysis and powder X-ray diffraction. Suprisingly, LMOF-1 has good stability in water and shows high selectivity and sensitivity in detecting Al3+ by significantly fluorescence-enhanced phenomenon with its LOD at 1.77×10−7M, which can meet the World Health Organization (WHO) standard for detecting Al3+ in drinking water. This work provides insights into the potential applications of Mn-based MOFs in chemical sensing.

Oxygen-Reduction-Triggered Cathodic Electrodeposition of Mn-Based Metal–Organic Framework Nanoflakes as Oxygen Evolution Electrocatalysts

Oxygen-Reduction-Triggered Cathodic Electrodeposition of Mn-Based Metal–Organic Framework Nanoflakes as Oxygen Evolution Electrocatalysts

Modification of carbon felt electrode by MnO@C from metal-organic framework for vanadium flow battery

The electrode, where electrochemical reactions are taken place, plays a vital role in the overall performance of vanadium flow batteries (VFBs). In this paper, a composite of manganese oxide and amorphous carbon was first synthesized from metal-organic frameworks and used as a catalyst to promote the electrochemical behavior of electrodes. The newly proposed catalyst was fabricated by a carbonization process of Mn-based metal-organic framework obtained by hydrothermal method. The morphology, composition, electrochemical activity and cell performance are respectively studied. The results show that: i) the catalyst carbonized at 900 °C possesses a smaller size, larger specific surface area, more oxygen-containing functional group and realizes superior electrochemical activity; ii) it helps the vanadium flow battery to increase its energy efficiency by 6% at 100 mA cm−2; iii) it is also beneficial to the working voltage, discharge capacity, high current density property and cycling performance of VFBs. Thus, this work can not only provide a new type of electrochemical catalyst for vanadium flow batteries, but also be significant to the improvement of the overall performance and conducive to the widespread application of vanadium flow batteries.

Reversal of Cisplatin Resistance in Ovarian Cancer by the Multitargeted Nanodrug Delivery System Tf-Mn-MOF@Nira@CDDP.

Cisplatin (CDDP) is a widely used chemotherapeutic drug with proven efficacy for treating tumors. However, its use has been associated with severe side effects and eventually leads to drug resistance, thus limiting its clinical application in patients with ovarian cancer (OC). Herein, we aimed to investigate the success rate of reversing cisplatin resistance using a synthetic, multitargeted nanodrug delivery system comprising a Mn-based metal-organic framework (Mn-MOF) containing niraparib (Nira) and CDDP alongside transferrin (Tf) conjugated to the surface (Tf-Mn-MOF@Nira@CDDP; MNCT). Our results revealed that MNCT can target the tumor site, consume glutathione (GSH), which is highly expressed in drug-resistant cells, and then decompose to release the encapsulated Nira and CDDP. Nira and CDDP play a synergistic role in increasing DNA damage and apoptosis, exhibiting excellent antiproliferation, migration, and invasion activities. In addition, MNCT significantly inhibited tumor growth in tumor-bearing mice and exhibited excellent biocompatibility without side effects. Furthermore, it depleted GSH, downregulated multidrug-resistant transporter protein (MDR) expression, and upregulated tumor suppressor protein phosphatase and tensin homolog (PTEN) expression, consequently reducing DNA damage repair and reversing cisplatin resistance. These results indicate that multitargeted nanodrug delivery systems can provide a promising clinical approach to overcoming cisplatin resistance. This study provides an experimental basis for further investigation into multitargeted nanodrug delivery systems to reverse cisplatin resistance in patients with OC.

Hierarchical spheroidal MOF-derived MnO@C as cathode components for high-performance aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) have shown great potential as energy storage devices owing to their high energy density, low cost, and low toxicity. Typically, high performance AZIBs incorporate manganese-based cathode materials. Despite their advantages, these cathodes are limited by significant capacity fading and poor rate performance due to the dissolution and disproportionation of manganese. Herein, hierarchical spheroidal MnO@C structures were synthesized from Mn-based metal–organic frameworks, which benefit from a protective carbon layer to prevent manganese dissolution. The spheroidal MnO@C structures were incorporated onto a heterogeneous interface to act as a cathode material for AZIBs, which exhibited excellent cycling stability (160 mAh g−1 after 1000 cycles at 3.0 A g−1), good rate capability (165.9 mAh g−1 at 3.0 A g−1), and appreciable specific capacity (412.4 mAh g−1 at 0.1 A g−1) for AZIBs. Moreover, the Zn2+ storage mechanism in MnO@C was comprehensively investigated using ex-situ XRD and XPS studies. These results demonstrate that hierarchical spheroidal MnO@C is a potential cathode material for high-performing AZIBs.

Three-dimensional urchin-like N/S co-doped Mn-based metal-organic frameworks for efficiently enabling oxygen reduction reaction

The exploration of economical and effective non-noble metal catalysts is essential for oxygen reduction reaction (ORR) in energy devices. Recently, heteroatom-doped metal-organic frameworks (MOFs) have shown great potential in ORR due to their high efficiencies and low costs. Herein, three-dimensional (3D) urchin-like N/S co-doped Mn-based MOFs (U–N/S–Mn-MOFs) as an effective ORR catalyst have been successfully prepared by a facile one-step solvothermal methodology. The unique 3D urchin-like structure with a spherical interior and dendritic exterior may provide more catalytic sites and transport channels for ORR. Simultaneously, the doped N and S combined with Mn can promote oxygen adsorption and reduce the reaction energy barrier. These characteristics endow U–N/S–Mn-MOFs with high ORR performance. The present work provides a new opportunity for multiple heteroatom-doped MOFs to achieve high electrocatalytic performance.

Rationally Designed Manganese-Based Metal-Organic Frameworks as Altruistic Metal Oxide Precursors for Noble Metal-Free Oxygen Reduction Reaction.

The sluggish oxygen reduction reaction (ORR) at the cathode is challenging and hinders the growth of hydrogen fuel cells. Concerning kinetic values, platinum is the best known catalyst for ORR; however, its less abundance, high cost, and corrosive nature warrant the development of low-cost catalysts. We report the hydrothermal synthesis of two novel Mn-based metal-organic frameworks (MOFs), [Mn2(DOT)(H2O)2]n (Mn-SKU-1) and [Mn2(DOT)2(BPY)2(THF)]n (Mn-SKU-2) (DOT = 2,5-dihydroxyterephthalate; BPY = 4,4'-bipyridine). Mn-SKU-1 contains dimeric Mn(II) centers where the two corner-shared MnO6 octahedra fuse to give rise to an infinite Mn2O10 cluster, whereas the two Mn(II) ions coordinate to DOT and BPY moieties to give rise to a pillared structure in Mn-SKU-2 and form a 3D → 3D homo-interpenetration MOF with a twofold interpenetrated net. The pyrolysis of as-synthesized Mn-MOFs at 600 °C under N2 produced exclusively porous α-Mn2O3 composites (PSKU-1 and PSKU-2), with the BET surface area of 90.8 (for PSKU-1) and 179.3 m2 g-1 (for PSKU-2). These mesoporous MOF-derived α-Mn2O3 composites were modified as cathode materials for the electrocatalytic reduction of oxygen. The onset potential for the oxygen reduction reaction was found to be 0.90 V for PSKU-1 and 0.93 V for PSKU-2 versus RHE in 0.1 M KOH solution, with the current density of 4.8 and 6.0 mA cm-2, respectively, at 1600 rpm. Based on the RDE/RRDE results, the electrocatalytic oxygen reduction occurs majorly via the four-electron process. The electrocatalyst PSKU-2 is cheap, easy to use, retains 90% of its activity after 10 h of continuous use, and offers higher recyclability than Pt/C. The onset potential maximum current density and kinetic values (Jk = 11.68 mA cm-2 and Tafel slope = 85.0 mV dec-1) obtained in this work are higher than the values reported for pure Mn2O3.

Metal-organic framework derived functional MnO2 via an in-situ oxidation strategy for advanced quasi-solid-state supercapacitors

Accurately controlling the morphology and structure of metal oxides faces huge challenges, which also limits their applications in different fields. Here, we report an in-situ oxidization strategy to design hollow spherical MnO2 (HS–MnO2) at room temperature based on the Mn-based metal-organic framework precursor. During the in-situ oxidization process, the obtained HS-MnO2 remains a hollow spherical structure with abundant pre-inserted Na+ and oxygen vacancies, which contributes to addressing its issues of volume expansion, low ionic diffusion rate, and low electronic conductivity. Consequently, the HS-MnO2 electrode exhibits high reversible capacitance (304.3 F g−1, 0.5 A g−1), high cycle stability (77.6% capacity retention for over 20,000 cycles at 10 A g−1), and excellent rate performance in supercapacitor applications. Importantly, the MnO2-based quasi-solid-state supercapacitor can power different devices, which shows its good application prospect. Our work provides new insights into the preparation of transition metal oxides with controllable structures via a mass-productive strategy with low cost to fulfill their potential in energy storage devices.

MRI Contrasting Agent Based on Mn-MOF-74 Nanoparticles with Coordinatively Unsaturated Sites.

The development of magnetic resonance imaging (MRI) contrasting agents (CAs) that are safer and have a higher relaxivity than Gd(III)-based agents is a significant research topic. Herein, we propose the use of a Mn-based metal organic framework (MOF), Mn-MOF-74, characterized by a safe paramagnetic center, a coordinatively unsaturated site (CUS) for aquation, and a long rotational correlation time, endowing high relaxivity. Furthermore, biocompatibility and delivery to the tumor are generally expected for MOFs that are obtainable in the nanometer size range. Drop-wise mixing of 2,5-dihydroxyterephthalic acid (DHTP) and Mn(II) acetate yielded Mn-MOF-74 with a diameter of < 150nm, which was then modified with 1-fivefold higher amounts of poly(ethylene glycol) (M.W. = 5000) to afford MOFs stably dispersed in water for at least 24h. The longitudinal and transverse relaxivity of the PEG-modified MOF was in the range of r1 = 8.08-13.5 and r2 = 32.7-46.8mM-1s-1, respectively (1.0T, 23.7-23.9°C), being larger than those of typical Gd(III)- and Mn(II)-based CAs of single-nuclear metal complexes. The in vivo imaging of a tumor-bearing mouse clearly showed that the tumor could be readily recognized due to signal enhancement (117%) in T1-weighted images, whereas other tissues showed small signal changes. These results suggest that PEG-Mn-MOF-74 can be passively delivered to tumors and can act as a high-relaxivity T1 agent.

Fast and stable Na insertion/deinsertion in double-shell hollow MnO nanospheres

MnO has received much attention at the anode material for sodium storage due to its low cost, environmental friendliness, and non-toxicity. However, many MnO-based electrodes exhibit poor cyclic stability, and very limited attention has been paid to the sodium storage mechanism of MnO. Herein, we report a self-templating method to synthesize uniform MnO double-shell hollow nanospheres. By thermally annealing the Mn-based metal organic framework precursor, Mn2O3 double-shell hollow nanospheres has been synthesized via a possible Ostwald ripening process and MnO double-shell hollow nanospheres is obtained by a subsequent thermal reduction of Mn2O3. When used as the anode material for sodium storage, the as-prepared MnO demonstrate a reversible capability of 261 mAh g−1 at 0.2 A g−1 after 200 cycles. Furthermore, compared with solid MnO without a hollow interior, the MnO double-shell hollow nanospheres exhibit a more stable retention of 81 mA h g−1 at 5 A g−1 after 2000 cycles, and a better rate performance of 97 mA h g−1 at 10 A g−1. Surprisingly, the ex-situ XRD results reveal that the sodium storage process of MnO is governed mainly by insertion/deinsertion reactions, while the conversion between Mn and Na2O only takes place to a little extent. Such a hollow construction allows a more stable structural integrity granting enhanced long-term cycling stability.

Mn-Based Hierarchical Polyhedral 2D/3D Nanostructures MnX2 (X = S, Se, Te) Derived from Mn-Based Metal–Organic Frameworks as High-Performance Electrocatalysts for the Oxygen Evolution Reaction

Three-dimensional (3D) nanomaterials are being explored extensively to serve as efficient electrocatalyts, which can be designed through the modification of electronic states of active sites in energy conversion applications. In this work, for the first time, a series of hierarchical polyhedral 3D nanostructures of Fe-doped manganese-based chalcogenides MnX2 (X = S, Se, Te) incorporating amorphous carbon (C) is synthesized using an Mn-based metal–organic framework as the precursor via a two-step hydrothermal route. The MnX2/C hierarchical polyhedral nanostructures (HPNs) (X = S, Se, Te) display remarkable results such as lower overpotentials of 305, 276, and 246 mV at a current density of 10 mA cm–2 and small Tafel slopes of 85, 90, and 48 mV dec–1, respectively. Moreover, iron-doped MnX2 (Fe–MnX2/C-HPNs, X = S, Se, Te) display improved electrocatalytic activity, achieving lower overpotentials of 280, 246, and 210 mV at a current density of 10 mA cm–2 and smaller Tafel slopes of 85, 65, and 48 mV dec–1, respectively. The enhanced efficiency of two-dimensional (2D)/3D hierarchical polyhedral nanostructures (Fe–MnX2/C-HPNs, X = S, Se, Te) is due to the larger specific surface area, easy charge transport, and integrated amorphous carbon. Hence, the construction of exceptionally efficient and low-cost electrocatalysts could be facilitated by this MOF-template approach for multilayer nanostructured materials for future applications.

BioMOF-Mn: An Antimicrobial Agent and an Efficient Nanocatalyst for Domino One-Pot Preparation of Xanthene Derivatives.

In this paper, a new Mn-based metal-organic framework [UoB-6] was obtained via a one-step ultrasonic irradiation method with the ligand (H2bdda: 4,4'-(1,4-phenylenebis(azaneylylidene))bis(methaneylylidene))dibenzoic acid. The structural integrity of the synthesized BioMOF-Mn was corroborated by FT-IR, EDX, ICP, XRD, TEM, DLS, FESEM, and BET-BJH analyses. The aerobic oxidative domino reaction of benzyl alcohols or aldehydes with dimedone derivatives was performed in the presence of the UoB-6 catalyst to produce xanthene derivatives in good yields. Hot filtration and Hg poisoning tests proved the heterogeneous nature of the catalyst. Novel synthesized xanthene-based bis-aldehydes were introduced as potent HDAC1 inhibitors according to molecular docking calculations. Finally, the inhibitory activities of Mn-MOF nanoparticles were evaluated on Escherichia coli and Candida albicans. The MIC, MBC, and MFC values were determined from 2048 to 4096 μg·mL-1 according to antimicrobial susceptibility testing methods. The inhibitory effects of antimicrobial agents can be exacerbated when loaded on BioMOFs.

Manganese-based metal-organic-framework derived hydrophilic cathode with carbon nanotubes introduced for long-life and high-performance aqueous zinc-ion battery

Aqueous zinc-ion batteries (ZIBs) have received widespread attention due to their high specific capacity (820 mA h g−1), high safety and low cost. Manganese (Mn)-based oxides show great potential as cathode materials for aqueous ZIBs, but they also face problems of low conductivity and poor rate performance. The introduction of carbon nanotubes (CNTs) can improve the hydrophilicity, enhance the conductivity of Mn-based oxides, and further improve the cycling performances of the ZIBs at high current density. Therefore, in this paper, Mn-based metal-organic-framework (Mn-MOF) is chosen as a template, while carboxylic CNTs are introduced during the synthesis process of Mn-MOF, finally after further calcination, composite material of Mn-based oxides, MOF-derived carbon and CNTs (MnOx@[email protected]) is prepared as the cathode for aqueous ZIBs. After 5000 cycles at a current density of 3 A g−1, the capacity retains 96.7 mA h g−1, while the capacity decay rate is 2% only. This work provides a solution to the challenges of Mn-based oxides for aqueous ZIBs cathode, thus achieve better electrochemical performances.

Metal-Organic Framework-Based Materials for Aqueous Zinc-Ion Batteries: Energy Storage Mechanism and Function.

Aqueous rechargeable zinc-ion batteries (ZIBs) featuring competitive performance, low cost and high safety hold great promise for applications in grid-scale energy storage and portable electronic devices. Metal-organic frameworks (MOFs), relying on their large framework structure and abundant active sites, have been identified as promising materials in ZIBs. This review comprehensively presents the current development of MOF-based materials including MOFs and their derivatives in ZIBs, which begins with Zn storage mechanism of MOFs, followed by introduction of various types of MOF-based cathode materials (PB and PBA, Mn-based MOF, V-based MOF, conductive MOF and their derivatives), and the regulation approaches for Zn deposition behavior. The key factors and optimization strategies of MOF-based materials that affect ZIBs performance are emphasized and discussed. Finally, the challenges and further research directions of MOF-based materials for advanced zinc-ion batteries are provided.

Polyaniline coated MOF-derived Mn2O3 nanorods for efficient hybrid capacitive deionization

Mn-based oxides are efficient pseudocapacitive electrode materials and have been investigated for capacitive deionization (CDI). However, their poor conductivity seriously affects their desalination performance. In this work, polyaniline coated Mn2O3 nanorods (PANI/Mn2O3) are synthesized by oxidizing a Mn-based metal organic framework (MOF) and subsequent in-situ chemical polymerization. The polyaniline not only acts as a conductive network for faradaic reactions of Mn2O3, but also enhances the desalination rate. PANI/Mn2O3 has a specific capacitance of 87 F g−1 (at 1 A g−1), superior to that of Mn2O3 nanorod (52 F g−1 at 1 A g−1). The hybrid CDI cell constructed with a PANI/Mn2O3 cathode and an active carbon anode shows a high desalination capacity of 21.6 mg g−1, superior recyclability with only 11.3% desalination capacity decay after 30 desalination cycles and fast desalination rate of 2.2 mg g−1 min−1. PANI/Mn2O3 is a potential candidate for high performance CDI applications.

Luminescent Mn-based metal-organic framework as an unusual detector to OH− and a multi-responsive sensor for Fe3+, Cr2O72− and CrO42− in aqueous media

Three new LMOFs titled, [Mn(TIPA)(ndc)(H2O)]n (LMOF-1), [Mn2Cl2(TIPA)2(oba)]n (LMOF-2), [Mn3O(TIPA)(oba)3]n (LMOF-3) (TIPA = tris(4-(1H-imidazole-1-yl)phenyl)amine, ndc = 1,4-naphthalene dicarboxylic acid, oba = 4,4’-oxydibenzoic acid) have been synthesized under solvothermal conditions. Single crystal diffraction analysis showed that LMOFs 1-3 were two-node network structures. LMOF-3 had a 2-fold interpenetrating 3D framework made up of pentahedron SBU with Mn3O(CO2)6 units as the core (The Mn3O(CO2)6 unit is defined as a pentahedral SBU). LMOF-1 and LMOF-2 on the other hand consist of six-coordinated octahedral structures with a single Mn atom as the core, with an uncoordinated carboxylate group in LMOF-1, selectively detecting Fe3+, CrO42- and Cr2O72− ions with high quenching constants and low detection limits of 14,647 M−1 and 2.505 × 10−5 M for Fe3+, 10,705 M−1 and 2.835 × 10−5 M for CrO42-, 6101 M−1 and 3.108 × 10−5 M for Cr2O72−. It is worth noting that the LMOF-1 exhibited excellent sensing performance for OH−

Metal–Organic Framework‐Templated Graphitic Carbon Confining MnO/Mn3O4 Nanoparticles via Direct Laser Printing for Electrocatalysis and Supercapacitor

AbstractTransition metal oxides with high specific capacities and variable electronic structures are of paramount importance for advanced energy conversion and storage, yet suffering from low electronic conductivity and poor structural stability during the electrochemical process. Herein, via direct laser printing on an Mn‐based metal–organic framework (Mn‐MOF) in air, MnO/Mn3O4 nanoparticles confined in mesoporous graphitic carbon can be mass‐produced rapidly. It is revealed that the structural transformations in manganese oxides (MnOx → Mn3O4 → MnO) occur during the decomposition of the Mn‐MOF and the MnO/Mn3O4 nanoparticles promote the catalytic graphitization of disordered carbon. The composite shows high electrocatalytic oxygen evolution reaction performances in the alkaline electrolyte with an overpotential of 394 mV at 10 mA cm−2 and good durability of 75% retention after 24 h. In addition, it also exhibits promising supercapacitive performances with a specific capacitance of 194 F g−1 and reasonable stability of 82% retention after 5000 cycles.