The evolution of α-MnO2 from hollow cubes to hollow spheres and their electrochemical performance for supercapacitors

Xie, Guomeng; Liu, Xin; Li, Qing; Lin, Hua; Li, Yuan; Nie, Ming; Qin, Lizhao

doi:10.1007/s10853-017-1116-4

Cited by 60 publications

(40 citation statements)

References 43 publications

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“…The spectrum of Au 4f in Figure 6E showed doublet peaks at 84.48 and 88.08 eV, confirming the presence of metallic Au(0) as the current collector. 55 Deconvolution of the O1s spectrum in Figure 6F 56,57 The spectrum of Mn 2p consisted of two distinct peaks at 642.58 and 657.28 eV, whose difference in binding energy was 11.7 eV, showing good agreement with previously reported values in the literature. 58 The electrochemical properties of the MnO 2 Aucotton electrodes were evaluated with a fixed size of electrodes with a 2 cm Â 1 cm active area, excluding the contact pad.…”

Section: Resultssupporting

confidence: 84%

Solution‐based deposition of nano‐embossed metal electrodes on cotton fabrics for wearable heaters and supercapacitors

Lee

Nam

et al. 2021

Intl J of Energy Research

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Cotton fabrics have received substantial attention as promising substrates for wearable electronics due to their large surface area and flexibility. Although the majority of studies have been devoted to fabricating electrodes utilizing cotton, the simple fabrication process of highly-conductive metal electrodes inserted in fabrics has yet to be achieved. Herein, we demonstrate the facile, electroless deposition of Au electrodes inserted in cotton by a seed-mediated, metal-growth strategy. The sequencable deposition of Au was achieved by the autocatalytic reduction of Au ions with Au nanoparticle seeds which were electrostatically deposited on cotton. The deposition efficiency was significantly improved by effectively removing physisorbed silane molecules on amine-modified cotton. The design was applied to various E-textiles, that is, wearable heaters, and energy storage devices. The cotton-based, wearable heater exhibited excellent Joule heating properties up to 120 C at 1 V within only 2 seconds. The wearable supercapacitor with cathode-deposited MnO 2 also demonstrated a promising, pseudo-capacitive performance of 167.55 F g À1 at 0.3 A g À1 .

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Section: Resultssupporting

confidence: 84%

Solution‐based deposition of nano‐embossed metal electrodes on cotton fabrics for wearable heaters and supercapacitors

Lee

Nam

et al. 2021

Intl J of Energy Research

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“…The O 1s spectra were shown in Figure 7E. The O 1s peaks at 529.5 and 531.6 eV can be attributed to the presence of MnO 2 and Ni‐O, respectively 46‐50 …”

Section: Resultsmentioning

confidence: 97%

“…The O 1s peaks at 529.5 and 531.6 eV can be attributed to the presence of MnO 2 and Ni-O, respectively. [46][47][48][49][50]…”

Section: X-ray Photoelectron Spectroscopy Analysismentioning

confidence: 99%

Optimization of prismatic type layered electrode materials for high performance sodium battery

et al. 2021

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The prismatic and octahedral type layered cathode materials can provide enhanced performance in sodium-ion batteries, due to low potential barrier during the intercalation. Among them, the prismatic layered Na-Ni-Mn-O system is the most preferable electrode with a high theoretical capacity of 173 mAhg −1 . The P2-type phase could be attained only by satisfying the conditions of alkali, and transition metal ratio 0.5 ≤ x ≤ 1. The P2-type layered structure in the Na-Ni-Mn-O system has been studied via optimizing the alkali and transition metals in two phases. Here, the vacuum assisted solid-state preparation method was carried out to avoid NiMnO 4 impurities. From diffraction analysis and refinement data, the structural changes were analyzed, then the optimal ratio for perfect P2-structure has been confirmed. The perfect P2-structure was obtained only for the samples Na 0.66 Ni 0.3 Mn 0.7 O 2 , Na 0.66 Ni 0.33 Mn 0.67 O 2 . The prepared materials showed the initial discharge capacity of 194 mAhg −1 at 0.1C. Highlights• Prismatic type layered Na-Ni-Mn-O electrodes synthesized via simple solidstate reaction.• The prepared electrode delivered initial capacity of 194 mAh g −1 at 0.1 C.• Mn richness maintains the low potential barrier for Na-ion during cycling.• This enhances the electrochemical performances of the material.• Increment of Nickel concentration enhance the unite cell volume.

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“…The XPS survey scan shown in Figure 6A clearly reports the presence of Mn (Manganese), O (Oxygen), and C (Carbon). A literature study shows that one way to determine the oxidation state of Mn is to find out the magnitude of difference in peaks (ΔE) of Mn2p [ 85 ] . Figure 6B shows ΔE values of 11.73 eV, 11.89 eV, and 11.76 eV measured from the spectra of Mn2p for MnO 2 , MnO 2 @400°C, and MnO 2 @600°C, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Oxygen vacancies (OV's) that arise from thermal defects are very sensitive to the crystal structure of manganese oxide. OV's in high proportion in a crystalline material can change the geometrical and electronic structure by elongating oxygen bonding (O‐O) for O adsorption, whereas on other hand, the presence of Optimized OV's content can enhance ORR kinetics that has been proved for β‐MnO 2 and λ‐MnO 2 [ 73–89 ] . Figure 6F‐H shows the deconvoluted peaks in high‐resolution spectra of Mn2p for MnO 2 , MnO 2 @400°C and MnO 2 @600°C.…”

Section: Resultsmentioning

confidence: 99%

Thermal optimization of manganese dioxide nanorods with enhanced ORR activity for alkaline membrane fuel cell

Ahmad

Nawaz

Ullah

et al. 2020

Electrochemical Science Adv

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In this study, pristine MnO2 catalyst was synthesized by hydrothermal technique and annealed at 400 and 600°C (MnO2@400°C and MnO2@600°C) transforming it into nanorods in a nitrogen atmosphere. The heat treatment process ameliorates the catalytic activity of the MnO2 catalyst by inducing oxygen vacancies. The catalyst is characterized by scanning electron microscope, and X‐ray diffraction, Fourier transforms infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and X‐ray Photoelectron Spectroscopy, whereas the oxygen reduction reaction (ORR) activity examined through rotating disc electrode and fuel cell test station. To elucidate the effect of sintering temperature on the MnO2 nanorods, the high angle annular dark‐field (HAADF) imaging was carried out on the samples. MnO2@400°C showed preeminent robustness to withstand austere alkaline environment during the experiment and possessed high electrocatalytic activity for the ORR with current density and onset potential values of 6.4 mA cm–2 and 0.80 V VS (RHE), respectively. The single‐cell test experiment of alkaline fuel cell delivered peak power density 81 mW/cm at 50°C. It is believed that this idiosyncratic behavior of MnO2 nanorods is due to the preferential growth on (211) and (310) indices and coexistence of optimized Mn4+/Mn3+ oxidation states as well as the creation of optimum oxygen vacancies on MnO2 nanorods. Moreover, the stretching of MnO2 nanorods occurs with increasing temperature and thus increasing the surface area to volume ratio. Thus thermal treatment shows that MnO2 is highly sensitive toward temperature variation and optimum ORR results can be obtained at adequate temperatures.

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The evolution of α-MnO2 from hollow cubes to hollow spheres and their electrochemical performance for supercapacitors

Cited by 60 publications

References 43 publications

Solution‐based deposition of nano‐embossed metal electrodes on cotton fabrics for wearable heaters and supercapacitors

Solution‐based deposition of nano‐embossed metal electrodes on cotton fabrics for wearable heaters and supercapacitors

Optimization of prismatic type layered electrode materials for high performance sodium battery

Thermal optimization of manganese dioxide nanorods with enhanced ORR activity for alkaline membrane fuel cell

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