Hierarchical MnO2 Research Articles

Electrochemical assessment of tailored Mn2O3 cuboidal hierarchical particles prepared using urea and Piperazine

This study synthesizes cuboidal-shaped hierarchical Mn2O3 (MNO) particles using a simple hydrothermal technique with Good's buffer piperazine and examines their electrochemical performance. The research explores how varying piperazine concentrations (piperazine concentration x in MNO-x) affect the structure and electrochemical properties of the MNO particles. X-ray diffraction (XRD) confirms the crystalline nature of MNO while scanning electron microscopy reveals that piperazine concentration influences the particles’ shape, size, and morphology. The MNO synthesized with 6 mmole piperazine (MNO-6) has the highest surface area of 8.67 m²/g. Electrochemical tests in 1 M and 6 M KOH electrolytes show that MNO-6 achieves the highest specific capacitance, with 440 F/g in 1 M and 952 F/g in 6 M KOH at a 1 mV/s scan rate. At a 1 A g-1 current density, MNO-6 exhibits a specific capacitance of ∼545.8 F/g in 1 M KOH and 809.0 F/g in 6 M KOH, with corresponding energy densities of 27.3 Wh/kg and 40.4 Wh/kg, and power densities of 315.7 W/kg and 365 W/kg, respectively. The superior electrochemical performance is attributed to the high surface area and porous structure of MNO synthesized with piperazine, highlighting its potential for advanced energy storage applications.

Unraveling the Fluoride-Induced Interface Reconstruction Across Lead-Based Hierarchical MnO2 Anode in Zinc Electrowinning.

Although the hierarchical manganese dioxide film electrode shows promise as a durable and catalytically active anode for zinc electrowinning, it often fails and deactivates when it is exposed to fluoride-rich environments. The lack of understanding regarding the mechanism behind fluoride-induced irreversible interface reconstruction hinders their practical application in large-scale energy-saving and pollution-reduction efforts. Here, we conducted multidimensional operando investigations to gain insights into the dynamic evolution across the film electrode interface with temporal and spatial resolution. Our findings reveal that electroosmosis of F- initially triggers structural collapse and subsequent reconstruction of [MnO6] units, followed by interaction with the spontaneous oxide film at the surface of lead substrate. Experimental studies and theoretical calculations indicate that F- facilitates the irreversible transformation of γ-MnO2 into more stable yet protective catalytic dual-defective α-MnO2. Additionally, lower levels of F- at the interface promote a change in microenvironmental pH within porous PbSO4, triggering the development of microporous corrosion-resistant β-PbO2 as the dominant phase. The combined effects of MnO2 and interphase evolution effectively explain the abnormally elevated oxygen evolution overpotential. Then, the proposed appropriate application scenarios based on the corrosion behavior will serve as a practical guide for the implementation of the hierarchical manganese dioxide film electrode.

Improved near-resonant two photon absorption of α-MnO2 nanowires surface functionalized reduced graphene oxide sheets

The versatile study of graphene derivatives has resurgence of interest on understanding its nonlinear optical response at different nanoscales. Nanostructured manganese dioxide: reduced graphene oxide (MnO2: rGO) hybrids were synthesized by reduction method by varying the content of rGO (5, 10, 15 & 20 wt%). X-ray Photoelectron Spectroscopy studies confirmed the surface functionalization of MnO2 on rGO. Field Emission Scanning Electron Microscopy (FESEM) and High-Resolution Tunnelling Electron Microscopy (HRTEM) witness that with respect to the content of rGO, the morphology of MnO2 varies radically from clusters to nanorods to nanowires over the surface of rGO sheets. Ground state absorption spectra of the hybrids have absorption edge at 268 nm corresponding to combined metal oxide charge transfer between rGO (π-π* transition of CC and n-π transition of C-O bonds) and MnO2 (d-d transition). Moreover, hierarchical MnO2 nanowire network resided on 2D rGO sheets involves broad absorption at the visible spectral domain due to polaron transition as well the localization of π- π* transited electrons that facilitates the probability of occurrence of excited state absorption. Intensity dependent open aperture Z-scan technique of the prepared hybrids using Q-switched Nd: YAG 532 nm nanopulsed laser reveals unusual transitions and enhanced nonlinear absorption. MnO2:(5 wt%) rGO shows saturable absorption (SA) at low intensity and changeover dynamically to reverse saturable absorption (RSA) at higher intensity. MnO2:(10 & 15 wt%) rGO exposes coupled nonlinear absorption (SA + RSA) owing to the combined effect of graphene (π-states) and MnO2 (σ-states). MnO2:(20 wt%) rGO exhibits a stronger RSA ascribed to sequential two photon absorption. The third-order nonlinear absorption coefficient and limiting threshold of MnO2: rGO (20 wt%) are 4.04 ×10-10 m/W and 0.84 ×1012 W/m2, which shows five-fold increase compared to bare rGO and MnO2. The obtained results propose that the optical nonlinearity of MnO2 nanowires surface functionalized rGO sheets can significantly be tuned to meet the requirements for fabricating laser safety devices.

Hydrothermal synthesis of NiO nanoparticles decorated hierarchical MnO2 nanowire for supercapacitor electrode with improved electrochemical performance

In this work, MnO2/NiO nanocomposite electrode materials have been synthesized by a cost-effective hydrothermal method. The effect of the concentrations (0, 1, 3, 5, and 7 wt%) of NiO nanoparticles on the surface morphology, structural properties, and electrochemical performance of the nanocomposites was characterized by different characterization techniques. The scanning electron micrographs (SEM) reveal that the as-prepared NiO nanoparticles are well connected and stuck with the MnO2 nanowires. The transmission electron microscopy (TEM) analysis showed an increase in the interplanar spacing due to the incorporation of NiO nanoparticles. The different structural parameters of MnO2/NiO nanocomposites were also found to vary with the concentration of NiO. The MnO2/NiO nanocomposites provide an improved electrochemical performance together with a specific capacitance as high as 343 F/g at 1.25 A/g current density. The electrochemical spectroscopic analysis revealed a reduction in charge transfer resistance due to the introduction of NiO, indicating a rapid carrier transportation between the materials interface. The improved electrochemical performance of MnO2/NiO can be attributed to good interfacial interaction, a large interlayer distance, and low charge transfer resistance. The unique features of MnO2/NiO and the cost-effective hydrothermal method will open up a new route for the fabrication of a promising supercapacitor electrode.

Design and synthesis of hierarchical MnO–Fe3O4@C/expanded graphite composite for sensitive electrochemical detection of bisphenol A

Hierarchically nanostructured binary transition metal oxide-based materials with high conductivity and catalytic activity are quite attractive for the electrochemical quantitative detection of environmental pollutants due to their natural abundance, variable oxidation state, and excellent synergies between metal sites. Herein, a new hierarchical MnO–Fe3O4@C/expanded graphite (EG) composite is designed and synthesized through a simple and in situ annealing method with the utilization of bimetallic organic framework (FeMn-MOF)/EG precursor. The synthesized MnO–Fe3O4@C/EG composite possesses a unique hierarchical nanoarchitecture that small-sized bimetallic oxide nanoparticles of 10–40 nm completely encapsulated by amorphous carbon layers of 2–4 nm are uniformly distributed on the EG platform. This distinctive structure combines the advantages of high conductivity, excellent catalytic activity, and strong stability. Resultantly, when it is applied to monitor environmental endocrine disruptors, the sensor exhibits a significant catalytic effect on the electrochemical oxidation of bisphenol A (BPA), inducing an amplified response current. In addition, the sensor shows a wide linear range of 1–50 μM and 50–400 μM for the BPA monitor, giving a sensitivity of 5208.8 and 1641.9 μA mM−1 cm−2, respectively. This study offers a new approach to design hierarchical binary metal oxide-based sensing materials as well as to explore their electrochemical properties and applications for the determination of emerging contaminants.

Engineering In Situ Catalytic Cleaning Membrane Via Prebiotic-Chemistry-Inspired Mineralization.

Pressure-driven membrane separation promises a sustainable energy-water nexus but is hindered by ubiquitous fouling. Natural systems evolved from prebiotic chemistry offer a glimpse of creative solutions. Herein, a prebiotic-chemistry-inspired aminomalononitrile (AMN)/Mn2+ -mediated mineralization method is reported for universally engineering a superhydrophilic hierarchical MnO2 nanocoating to endow hydrophobic polymeric membranes with exceptional catalytic cleaning ability. Green hydrogen peroxide catalytically triggered in-situ cleaning of the mineralized membrane and enabled operando flux recovery to reach 99.8%. The mineralized membrane exhibited a 9-fold higher recovery compared to the unmineralized membrane, which is attributed to active catalytic antifouling coupled with passive hydration antifouling. Electron density differences derived from the precursor interaction during mediated mineralization unveiled an electron-rich bell-like structure with an inner electron-deficient Mn core. This work paves the way to construct multifunctional engineered materials for energy-efficient water treatment as well as for diverse promising applications in catalysis, solar steam generation, biomedicine, and beyond.

Hollow engineering of sandwich NC@Co/NC@MnO2 composites toward strong wideband electromagnetic wave attenuation

Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption, but still remain the formidable challenges in decreasing filler loadings. Herein, sandwich NC@Co/NC@MnO2 composites with hollow cavity, multiple hetero-interfaces, and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrothermal reaction. In the sandwich composites, middle magnetic components (Co/NC) are wrapped by inner N-doped carbon (NC) matrix and outer hierarchical MnO2 nanosheets. Importantly, hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorption bandwidth without sacrificing the absorption intensity. The maximum reflection loss of sandwich NC@Co/NC@MnO2 composites reaches -44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm. These results provide us a new insight into preparing efficient electromagnetic wave absorbers by interface engineering and hollow construction.

Hollow Co/NC@MnO2 polyhedrons with enhanced synergistic effect for high-efficiency microwave absorption

High-efficiency microwave absorbents with lightweight characteristics possess prospective applications in electromagnetic radiation protection, but still face huge challenges. Herein, hollow Co/NC@MnO2 (H–Co/NC@MnO2) polyhedrons with hierarchical structure and enhanced synergistic effect are successfully fabricated via the collaborative steps of etching-pyrolysis-hydrothermal reaction. Specifically, hollow engineering of Co/NC with heteroatoms endow the polyhedrons with lightweight characteristics, dipolar polarization and magnetic loss, hierarchical MnO2 nanosheets with oxygen vacancies grant dielectric loss and multiple scattering, and the dielectric-magnetic synergistic effect between Co/NC and MnO2 promote impedance matching and strengthen interfacial polarization. Benefiting from the above mentioned advantages, the H–Co/NC@MnO2 polyhedrons exhibit high-efficiency microwave attenuation at a low filler loading of 20 wt%. The optimal reflection loss reaches −54.7 dB and the effective absorption bandwidth ranges from 11.8 GHz to 18 GHz (6.2 GHz) with a thickness of only 2.1 mm. These findings provide us a promising strategy in developing high-efficiency and lightweight microwave absorbents for practical applications.

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.

Low-Temperature NH3-SCR over Hierarchical MnO x Supported on Montmorillonite Prepared by Different Methods.

Hierarchical MnO x pillared or supported on montmorillonite were prepared by three methods, i.e., impregnation (IM), chemical precipitation (CP), and in situ deposition (SP). The catalysts were characterized by low-temperature N2 adsorption (BET), XRD, XPS, SEM, TEM, H2-TPR, NH3-TPD, NO-TPD, TPSR, in situ DRIFTS, and evaluation of catalytic performance for NH3-SCR. The best catalytic performance was obtained for catalysts prepared by SP in terms of activity and selectivity, obtaining >90% NO conversion with >95% selectivity to N2 in 100-300 °C and GHSV of 70,000 h-1. Compared to IM and CP, SP greatly simplified catalyst preparation, resulting in higher BET surface areas; a spongy pore structure; more highly dispersed, pillared MnO x species; and higher density of acid sites distributed on catalysts surface, which all contributed to its superior performance for NH3-SCR. The activity for low-temperature NH3-SCR of manganese catalysts could be widely tailored by preparation methods.

Rational design of hierarchical yolk-double shell Fe@NCNs/MnO2 via thermal-induced phase separation toward wideband microwave absorption

Rational design of yolk-shell architectures with synergistic effect are vital for improving microwave attenuation ability, but still face challenges. In this work, we employ the thermal-induced phase separation engineering and redox strategy to fabricate hierarchical yolk-double shell Fe@NCNs/MnO2, in which magnetic Fe units are individually confined in N-doped carbon nanocubes (NCNs) cavity and hierarchical MnO2 nanosheets are intimately anchored on NCNs surface. It is found that the phase separation process between Prussian blue and poly-dopamine is significantly determined by the thermal-induced inward contraction owing to their different thermal stabilities and independent crystal structures. As results, the hierarchical composites exhibit matched impedance and wideband microwave absorption owing to the internal cavity architectures, multiple hetero-interfaces, dielectric-magnetic synergistic effect and hierarchical conformations. The minimum reflection loss reaches −46.7 dB with 3.3 mm thickness, and more importantly, the effective bandwidth (<-10 dB) achieves as strong as 10.8 GHz at 3.1 mm. This work opens up a novel and meaningful thinking for the construction of yolk-double shell architectures and the synthesized hierarchical composites can be used as promising candidates in addressing electromagnetic pollution.

A novel hierarchical porous carbon-supported MnO2 nanofibers composite with three-dimensional interpenetrating network structure as a high-performance supercapacitor

For improving the conductivity of porous carbon and the utilizations of its pore structures, a hierarchical porous carbon (HPC) had been developed with highly fluffy three-dimensional (3D) continuous network structure. Using the HPC as a support, a novel MnO2@HPC composite with 3D interpenetrating network structure was prepared as electrode material of supercapacitor via simple hydrothermal method. When the hydrothermal reaction temperature was 100°C, the MnO2 nanofibers (∼5 nm) were uniformly grown on and within the fluffy 3D porous network of the HPC, forming a composite with interpenetrating network structure. The as-prepared composite (MnO2@HPC-100) exhibited the characteristics of both electric double-layer capacitance and pseudo-capacitance, which had a high specific capacity of 368 F g−1 at a current density of 0.5 A g−1 and 186 F g−1 at 10 A g−1 (50.5% retention). In addition, the asymmetric supercapacitor device was assembled with a relatively high energy density of 88.2 Wh Kg−1 at a power density of 162 W Kg−1. The device had a high capacity retention rate of 95% after 10000 cycles, and the coulomb efficiency was stable at 99.7%, showing the excellent stability of the composite. Therefore, the MnO2@HPC-100 composite has great application prospects in energy storage.

Singlet oxygen-dominated activation of peroxymonosulfate by 3D hierarchical MnO2 nanostructures for degradation of organic pollutants in water: Surface defect and catalytic mechanism

Manganese dioxide (MnO2) is attracting significant attention in the activation of persulfate for the degradation of organic pollutants in water. But the factor determining the catalytic efficiency of MnO2, and the evolution of reactive oxygen species (ROS) remain equivocal and elusive. Herein, three-dimensional (3D) hierarchical MnO2 nanostructures are synthesized via the calcination of hydrothermal product and used to active peroxymonosulfate (PMS) for degradation of acid orange 7 (AO7) in water. The results show that the calcination temperature can tune the morphology of 3D hierarchical MnO2 nanostructures from flower to urchin-like as well as phase transformation from δ-MnO2 to α-MnO2. Owing to the presence of more surface defects and surface adsorbed oxygen species, the urchin-like α-MnO2 nanostructures prepared at 500 °C (MnO2-500) deliver the best catalytic activity in activation of PMS, and 98.3 % of AO7 is degraded in 300 s. Additionally, the MnO2-500 shows wide pH applicability (3.5–9.6). Quenching tests and electron paramagnetic resonance spectra reveal that the catalytic oxidation of AO7 in the MnO2-500/PMS system is mainly mediated by the non-radical pathway, and the dominated ROS is 1O2. Besides, electrochemical experiment confirms the presence of electron transfer in the catalytic process. Density functional theory calculations indicate that the CN and CS groups of AO7 with high electron density are easily attacked by electrophilic ROS, which is further confirmed by liquid chromatography-mass spectrometry. Finally, MnO2-500 exhibits gradually enhanced catalytic activity with the increased cycle number due to the increased surface defects and the surface adsorbed oxygen. This study provides new insight into the PMS activation by MnO2-based catalyst for the remediation of organic pollutants in water.

In Situ Self-Anchored Growth of MnO2 Nanosheet Arrays in Polyaniline-Derived Carbon Nanotubes with Enhanced Stability for Zn–MnO2 Batteries

Aqueous Zn–MnO2 batteries have received much attention due to their low cost, safety, reliability, and large storage capacity. However, the sluggish ion/electron transport kinetics of bulk MnO2 inevitably decreases the rate capability and cycle stability of Zn–MnO2 batteries. Herein, hierarchical MnO2 nanosheet arrays self-anchored and grown in polyaniline-derived carbon nanotubes (PCNT@MnO2, denoted as PCMO) with enhanced stability are prepared by employing PCNT as both a substrate and a sacrificial reductant. The hollow PCNT conductive skeleton feature and robust integrated MnO2 nanosheet arrays in PCMO are not only favorable for enhancing electronic conductivity and accelerating electronic migration but also provide effective nucleation sites for the growth of MnO2 nanosheets and unimpeded ion channels, resulting in high specific capacity, rapid ion-diffusion kinetics, and long-term cycle stability. Specifically, the optimized PCMO material (PCMO-2) can deliver 264 mAh g–1 at 0.2 A g–1 after 120 cycles without obvious capacity decay, superior to the bare MnO2 material. Moreover, the as-fabricated PCMO//Zn battery can exhibit a high energy density of 320.2 Wh kg–1 at a power density of 120 W kg–1. The rational design of low-cost and integrated core–shell architecture with robust contact between MnO2 nanosheet arrays and a hollow conductive skeleton is expected to achieve cost-effective and high-performance Zn–MnO2 batteries.

Designing hierarchical MnO/polypyrrole heterostructures to couple polysulfides adsorption and electrocatalysis in lithium-sulfur batteries

Efficiency of entrapping and conversion toward lithium polysulfides (LiPSs) plays a key role in promoting the utilization of sulfur and regulating LiPSs redox in lithium-sulfur (Li–S) batteries. However, a well-designed electrocatalyst with abundant active centers to facilitate conversion of LiPSs and prolong the lifespan of Li–S batteries is still required. Herein, a novel heterostructure of polypyrrole (PPy) nanotubes composite with hierarchical MnO (MnO/PPy-2) was designed as a host. N-containing functional groups and p-conjugated structures in PPy and polar MnO supply proper trapping ability toward LiPSs. More polar (=C–N + ) and Mn–OH bonds are beneficial for electron transfer on conductive PPy substrate, which guarantee the uniform deposition of Li 2 S. Moreover, the hierarchical structure provides abundant surface and active sites for LiPSs entrapping and catalyzing, avoiding the electric contact loss. The synergetic merits of proper adsorption and conversion make MnO/PPy-2 composite a competitive host in the Li–S field. The cathode (S–MnO/PPy-2) exhibits a superior rate performance and cycling stability enabling 1000 cycles at 1 C with 0.032% capacity loss per cycle. This work paves a way to fabricate and utilize conductive polymer/metal oxides heterostructures as catalyst in Li–S batteries and provides a new sight to understand catalyst design in energy storage devices. • Polypyrrole (PPy) and polar MnO supply proper trapping ability towards LiPSs. • Conductive bonds are beneficial for electric contact between LiPSs and substrate. • The hierarachical structure facilitates LiPSs entrapping and catalyzing.

N-doped carbon coated porous hierarchical MnO microspheres as superior additive-free anode materials for lithium-ion batteries

Novel N-doped carbon coated porous hierarchical MnO microspheres have been successfully synthesized via the simultaneous pyrolysis of MnCO3 and polyacrylonitrile (PAN) at low calcination temperature. The micro/nano structure with uniform N-doped carbon coating, suitable interior pores and tiny primary MnO nanocrystals can significantly increase the electronic conductivity of the composite, reduce the amount of irreversible solid-electrolyte interphase (SEI) layer, accommodate the huge volume change of MnO during cycling and facilitate easier redox reaction of Mn2+/Mnx+ (x>2) to generate extra capacity. By using partially pyrolytic PAN as the conductive agent and binder, the obtained additive-free MnO-based electrode (MnO@NC-S) demonstrates a high reversible capacity of 998 mAh g−1 after 100 cycles at 0.1 A g−1 and remarkable long-term cycling stability with the capacity of 629 mAh g−1 after 500 cycles at 0.5 A g−1.

Singlet Oxygen-Dominated Activation of Peroxymonosulfate by 3d Hierarchical Mno2 Nanostructures for Degradation of Organic Pollutants in Water: Surface Defect and Catalytic Mechanism

Singlet Oxygen-Dominated Activation of Peroxymonosulfate by 3d Hierarchical Mno2 Nanostructures for Degradation of Organic Pollutants in Water: Surface Defect and Catalytic Mechanism

Hierarchical MnO2 Nanosheets Grown on Cotton Fabric as a Flexible and Washable Solar Evaporator for Seawater Desalination

Hierarchical MnO₂ Nanosheets Grown on Cotton Fabric as a Flexible and Washable Solar Evaporator for Seawater Desalination

Flexible and Safe Zinc/SS – Cu and Bi Incorporated Binder Free Hierarchical MnO2 Alkaline Solid-State Battery with High-Capacity Utilization and Long Cycle Life for Wearable Applications.

Wearable electronics are one of the most rapidly growing industries, due to their extended use in everyday applications resulting in an increased demand for portable energy storage devices. Despite immense success in commercialization of Lithium-ion batteries (LIBs), conventional LIBs suffer from issues of cost and safety. The expanding need for cheaper, and safer energy storage devices led explorations towards alternatives. After careful considerations, Zinc (Zn)-Manganese dioxide (MnO2) based alkaline system was chosen to be investigated in this work due to its low cost, inherent safety, and high theoretical energy density. However, challenges associated with making the aforementioned system rechargeable and highly performing still remains. The work in this study is directed towards enhancing the overall performance of the Zn-MnO2 alkaline battery in addition to making it suitable for flexible and wearable applications. A highly ionically conducting polymer electrolyte ({5}CP) with excellent physical and electrochemical stability primarily comprising biopolymer chitosan is prepared by using a time and energy-efficient technique. Incorporation of this polymer electrolyte with Zn anode and MnO2 cathode enabled the successful preparation of a physically flexible cell. To obtain high cyclability and performance of the system; issues of inactive phase formations (MnxOy, ZnMnxOy), low active material availability, pronounced shape changes at the anode surface, and zincate ion transfer towards cathode were overcome by enhancing the electrochemically active layers in the system. The assembled cell comprising the enhanced fabricated layers; (i.e. a Zinc/Stainless steel mesh composite anode, a hierarchical binder-free bismuth and copper additives based MnO2 cathode, and a chitosan-based polymer electrolyte with calcium hydroxide additive) indicated excellent rate capabilities (486 mAh/g @ 0.1 A/g, 278.9 mAh/g @ 2 A/g & 172.8 mAh/g @ 5 A/g), high capacity utilization (78% of the theoretical 2-electron capacity on MnO2), long cycling stabilities (70% retention over 1000 cycles), and good energy densities (155 – 400 Wh/kg @ 0.1 – 1 A/g). Moreover, a number of destructive tests such as being bent, hammered, pressurized, and punctured were conducted on the pouch cell fabricated using the above-mentioned layers to analyze the cells’ safety, reliability, and robustness. Results indicated not much deterioration in capacities. Additionally, when the cell was bent and tested for long performance; a stable discharge capacity (270 mAh/g @ 1 A/g) was obtained after 250 cycles, thus attesting to excellent cycling stability. The successful working of the fabricated cell was validated by lighting up an LED. The successful findings presented in this study can chart new pathways to the development of safe, flexible, cost-effective, and more environmentally responsible alternative energy storage sources for wearables.

Introducing hierarchical hollow MnO2 microspheres as nanozymes for colorimetric determination of captopril.

A simple sensor was developed for the colorimetric determination of captopril (CPT). Herein, hierarchical hollow MnO2 microspheres (HH-MnO2) were applied as nanozymes with peroxidase-mimetic activity. Free cation radicals with a strong absorption signal (λmax at 653nm) were generated via a redox reaction between 3, 3', 5, 5'-tetramethylbenzidine (TMB) and HH-MnO2. Captopril could successfully prevent the generation of blue-colored free cation radicals. The influence of CPT concentration on the absorption of the generated radicals was monitored by UV-Vis spectroscopy. The corresponding linear concentration range was from 1.0 to 30.0μgmL-1 (4.6-138.1μmolL-1), and the detection limit was found to be 0.26μgmL-1 (1.2μmolL-1). As a practical usage, the developed sensor was effectively utilized to measure the content of CPT in pharmaceutical formulations.