Amorphous MnO<sub>2</sub> surviving calcination: an efficient catalyst for ozone decomposition

Manganese dioxide (MnO2) is a promising photo–thermo–electric‐responsive semiconductor material for environmental applications, owing to its various favorable properties. However, the unsatisfactory environmental purification efficiency of this material has limited its further applications. Fortunately, in the last few years, significant efforts have been undertaken for improving the environmental purification efficiency of this material and understanding its underlying mechanism. Here, the aim is to summarize the recent experimental and computational research progress in the modification of MnO2 single species by morphology control, structure construction, facet engineering, and element doping. Moreover, the design and fabrication of MnO2‐based composites via the construction of homojunctions and MnO2/semiconductor/conductor binary/ternary heterojunctions is discussed. Their applications in environmental purification systems, either as an adsorbent material for removing heavy metals, dyes, and microwave (MW) pollution, or as a thermal catalyst, photocatalyst, and electrocatalyst for the degradation of pollutants (water and gas, organic and inorganic) are also highlighted. Finally, the research gaps are summarized and a perspective on the challenges and the direction of future research in nanostructured MnO2‐based materials in the field of environmental applications is presented. Therefore, basic guidance for rational design and fabrication of high‐efficiency MnO2‐based materials for comprehensive environmental applications is provided.

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“…[ 516 ] Manganese oxides especially MnO 2 , are the most frequently studied catalytic materials for O 3 elimination. [ 168,283,371,517–523 ]…”

Section: Environmental Applicationsmentioning

confidence: 99%

“…The researchers have found that amorphous MnO 2 , [ 522 ] α‐MnO 2 , [ 168,517 ] birnessite‐type MnO 2 , [ 524,525 ] δ‐MnO 2 , [ 526 ] γ‐MnO 2 , [ 519,527 ] and ε‐MnO 2 [ 528 ] have all shown superior O 3 ‐removal performances. Zhang et al.…”

Section: Environmental Applicationsmentioning

confidence: 99%

MnO₂‐Based Materials for Environmental Applications

et al. 2021

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“…The active components of the catalyst mainly include noble metals [13][14][15] and transition metal oxides. [16][17][18][19] Imamura et al reported that p-type semiconductors have higher decomposition efficiency for ozone than n-type semiconductors. 20 Oyama measured the conductivity of the catalyst by the Hall effect and compared the correlation between oxide activity and conductivity, thereby further conrming that the p-type semiconductor oxide has higher activity for the catalytic decomposition of ozone.…”

Section: Introductionmentioning

confidence: 99%

Gram-scale synthesis of ultra-fine Cu₂O for highly efficient ozone decomposition

et al. 2020

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“…prepared a series of amorphous MnO 2 nanoparticles through the calcination process for ozone decomposition and the crystallinity was regulated through different varying temperatures. [ 65 ] They reported that calcination temperature has an odd significant effect on morphology, texture, and surface chemistry of MnO 2 and MnO 2 nanoparticles calcined at 300°C (MnO 2 ‐300) exhibits superior electrocatalytic activity for ozone decomposition that is due to large surface area and high OV's. [ 65 ]…”

Section: Introductionmentioning

confidence: 99%

“…[ 65 ] They reported that calcination temperature has an odd significant effect on morphology, texture, and surface chemistry of MnO 2 and MnO 2 nanoparticles calcined at 300°C (MnO 2 ‐300) exhibits superior electrocatalytic activity for ozone decomposition that is due to large surface area and high OV's. [ 65 ]…”

Section: Introductionmentioning

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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Amorphous MnO₂ surviving calcination: an efficient catalyst for ozone decomposition

Abstract: Calcination at 300 °C of amorphous MnO2 maintains the structure and results in superior stability owing to the enhanced water-resistant ability.

Cited by 66 publications

References 58 publications

MnO₂‐Based Materials for Environmental Applications

MnO₂‐Based Materials for Environmental Applications

Gram-scale synthesis of ultra-fine Cu₂O for highly efficient ozone decomposition

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

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Amorphous MnO2 surviving calcination: an efficient catalyst for ozone decomposition

Abstract: Calcination at 300 °C of amorphous MnO2 maintains the structure and results in superior stability owing to the enhanced water-resistant ability.

Cited by 66 publications

References 58 publications

MnO2‐Based Materials for Environmental Applications

MnO2‐Based Materials for Environmental Applications

Gram-scale synthesis of ultra-fine Cu2O for highly efficient ozone decomposition

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

Contact Info

Product

Resources

About

Amorphous MnO₂ surviving calcination: an efficient catalyst for ozone decomposition

MnO₂‐Based Materials for Environmental Applications

MnO₂‐Based Materials for Environmental Applications

Gram-scale synthesis of ultra-fine Cu₂O for highly efficient ozone decomposition