Vibrational and electron paramagnetic resonance spectroscopic studies of β-MnO2 and α-K MnO2 nanorods

Barudžija, Tanja; Cvjetićanin, Nikola; Bajuk–Bogdanović, Danica; Mojović, Miloš; Mitrić, Miodrag

doi:10.1016/j.jallcom.2017.09.015

Cited by 20 publications

(14 citation statements)

References 49 publications

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“…Sample 2 has relatively sharp peaks indicative of a well-developed hollandite-type α-MnO 2 structure with an interstitial space consisting of narrow one-dimensional (2 × 2) channels. Infrared bands at about 430, 470, 520, 550, 600 cm −1 in the same spectrum are in agreement with [43]. Spectra of samples 3-5 are diffuse and have similarity to sample 1 with ramsdellite structure in this region due to complex composition and nonstoichiometry of electrodeposition products in agreement with XRD data (Table I and [7]).…”

Section: Resultssupporting

confidence: 81%

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ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides

et al. 2018

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The ionic dopant additives have different mechanisms of their influence upon MnO2 electrocrystallisation process and depending on dopants added the following polymorphs are stabilised: α-MnO2 (hollandite, I4/m) -NH + 4 ; γ-MnO2 (ramsdellite, P bnm) -Co 2+ , Fe 2+ ; layered polymorph δ-MnO2 (birnessite, C2/m) -Cr 3+ . The defect states of intergrowth method in ramsdellite matrix and twinning, OH groups studied by X-ray diffraction and the Fourier transform infrared mtehod, respectively, indicate their high content in case of Fe 2+ and Co 2+ -doped manganese dioxide. CVA oxygen reduction reaction peaks were established after experiments in alkaline electrolytes and dioxygen (argon, air) atmosphere. Activity of doped samples studied is comparable with other published data. Both doped with Co 2+ and Fe 2+ samples display maximal currents and some distinctive features in oxygen reduction reaction.

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Section: Resultssupporting

confidence: 81%

“…Infrared spectroscopy of manganese oxides is sensitive to amorphous component in addition to phase components with long-range order [43] unlike XRD. Our FTIR spectra were registered in the range of 400-4000 cm −1 (Fig.…”

Section: Resultsmentioning

confidence: 99%

ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides

et al. 2018

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“…The EPR spectra of α -K x MnO 2 nanorods contain two signals. One is attributed to Mn 4+ ; the other one to manganese in mixed-valence Mn 4+ /Mn 3+ environment close to K + ions [89]. Urchin-like α -MnO 2 materials were also prepared through a simple precipitation reaction of H 2 SO 4 and KMnO 4 in aqueous solution heated at 85 °C [90].…”

Section: Synthesis Of Mno2 Nanomaterialsmentioning

confidence: 99%

“…In contrast, Li et al [121] claimed the need of Ag + ion (via AgNO 3 solution) as catalyst agent for the crystallization of α -MnO 2 core-shell urchin-like structures. Urchin-like α -MnO 2 nanomaterials were also prepared without template or surfactant by a simple precipitation reaction of H 2 SO 4 and KMnO 4 in aqueous solution [89]. Urchins are composed of aggregated crystalline nanorods with a mean diameter of 10 nm and a length of 200 nm.…”

Section: Mno2 Nanostructures: Example Of Nanourchinsmentioning

confidence: 99%

Nanostructured MnO2 as Electrode Materials for Energy Storage

2017

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Manganese dioxides, inorganic materials which have been used in industry for more than a century, now find great renewal of interest for storage and conversion of energy applications. In this review article, we report the properties of MnO2 nanomaterials with different morphologies. Techniques used for the synthesis, structural, physical properties, and electrochemical performances of periodic and aperiodic frameworks are discussed. The effect of the morphology of nanosized MnO2 particles on their fundamental features is evidenced. Applications as electrodes in lithium batteries and supercapacitors are examined.

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“…We pay a special attention to characterize the crystal chemistry of α-type MnO2 prepared from redox reaction of potassium permanganate, which always contains a residual fraction of K + ions in the 2×2 tunnels preserving the structural stability of this material. Note that most of numerous works published in the literature neglect this aspect; only few papers consider the presence of potassium in the cryptomelane framework [44][45][46][47][48][49][50][51]. Two samples were prepared using a redox synthesis…”

Section: Introductionmentioning

confidence: 99%

Electrochemical performance of nanosized MnO2 synthesized by redox route using biological reducing agents

Abuzeid

Hashem

Kaus

et al. 2018

Journal of Alloys and Compounds

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For more than a century, manganese dioxides (MDOs) have been used as electrochemically active materials in energy storage and conversion applications. To reduce the cost and hazardous impact of synthesis, a redox method was used to prepare MnO2 using extracts of green (GT-MnO2) and black (BT-MnO2) tea as biological reducing agents. Polyphenols present in the extracts of tea not only reduce Mn 7+ ions but also act as "capping agents" to stabilize and prevent the produced MnO2 nanoparticles from degradation and aggregation. Elemental, structural properties and morphology of nanosized α-KxMnO2 were studied by thermogravimetric analysis, X-ray powder diffraction and Raman spectroscopy, which revealed the different crystallinity between GT-MnO2 and BT-MnO2 due to the strength of the antioxidant species. Electrochemical investigations highlight the beneficial presence of K + ions in (2×2) tunnels; with a higher concentration, α-K0.135MnO2 exhibits a discharge specific capacity of 155 mAh g-1 after 20 cycles at C/26 rate.

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Vibrational and electron paramagnetic resonance spectroscopic studies of β-MnO2 and α-K MnO2 nanorods

Cited by 20 publications

References 49 publications

ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides

ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides

Nanostructured MnO2 as Electrode Materials for Energy Storage

Electrochemical performance of nanosized MnO2 synthesized by redox route using biological reducing agents

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Vibrational and electron paramagnetic resonance spectroscopic studies of β-MnO2 and α-K MnO2 nanorods

Cited by 20 publications

References 49 publications

ORR Electrocatalysis on Cr3+, Fe2+, Co2+-Doped Manganese(IV) Oxides

ORR Electrocatalysis on Cr3+, Fe2+, Co2+-Doped Manganese(IV) Oxides

Nanostructured MnO2 as Electrode Materials for Energy Storage

Electrochemical performance of nanosized MnO2 synthesized by redox route using biological reducing agents

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ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides

ORR Electrocatalysis on Cr³⁺, Fe²⁺, Co²⁺-Doped Manganese(IV) Oxides