Periodical structural conversion and its mechanism in hematite: from nanospindles, to nanotubes, to nanotires

Liu, Chunting; Ma, Ji; Chen, Houyang

doi:10.1039/c1ra00595b

Cited by 21 publications

(11 citation statements)

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“…However, the thickness of the Fe 2 O 3 thin film is not uniform, in accordance with the rough surface morphology observed through FESEM, and varies within 2–5 nm, as can be observed clearly from Figures f and S4(a) (Supplementary Information). High resolution TEM image (Figure S4(b), Supplementary Information) also shows well resolved lattice fringes with separation of ∼0.25 nm which matches well with the interplanar spacings of (110) lattice planes of rhombohedral Fe 2 O 3 . Figure g shows the scanning TEM (STEM) image where the contrast difference between core and shell regions of the NC can be further identified.…”

Section: Resultssupporting

confidence: 83%

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe₂O₃@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Singh

Sarkar

2019

ChemCatChem

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Solar driven photoelectrochemical (PEC) water splitting is a clean and sustainable approach to generate green fuel, Hydrogen. Hematite (Fe 2 O 3 ) is considered as potential photoanode because of its abundance, chemical stability and suitable band gap, though its short carrier diffusion length puts a limit on the film thickness and subsequent light absorption capability. In this regard, here we have designed and constructed a unique photoanode by depositing ultrathin films of Fe 2 O 3 on purposebuilt three-dimensional (3D) nickel nanocone arrays. In this design, 3D nanostructures not only provide ameliorated surface area for PEC reactions but also enhance light absorption capability in ultrathin Fe 2 O 3 films, while ultrathin films promote charge carrier separation and effective transfer to the electrolyte. The 3D electrodes exhibit a substantial improvement in light absorption capability within the entire visible region of solar spectrum, as well as enhanced photocurrent density as compared to the planar Fe 2 O 3 photoelectrode. Detailed investigation of reaction kinetics suggests an optimum Fe 2 O 3 film thickness on 3D nanocone arrays obtained after 6 deposition cycles in achieving maximum charge carrier separation and transfer efficiencies (82 % and 88 %, respectively), mainly ascribable to the increased charge carrier lifetime overcoming recombination losses.

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Section: Resultssupporting

confidence: 83%

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe₂O₃@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Singh

Sarkar

2019

ChemCatChem

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“…For example, Chen et al 11 synthesized uniform hexagonal a-Fe 2 O 3 nanoplates by a facile alcohol-thermal reaction and produced a new a-Fe 2 O 3 nanostructure. 16 Although there have been a number of reports about a-Fe 2 O 3 nanoplates and nanospindles, there has been no report of the continuous tuning of shape from nanoplates to nanospindles in an experimental system using NO 3 À ions and NH 3 molecules. Hexagonal a-Fe 2 O 3 nanoplates were prepared through a hydrothermal method with the addition of Al 3+ ions.…”

Section: Introductionmentioning

confidence: 99%

Effect of sequential morphology adjustment of hematite nanoplates to nanospindles on their properties and applications

et al. 2015

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We investigated the marked morphological changes of a-Fe 2 O 3 nanocrystals from nanoplates to nanospindles via an environmentally friendly hydrothermal route. An aqueous Fe salt was used as the precursor and the volume ratio of ammonia to ethylene glycol was varied. The product was uniform and obtained at a high yield. By simply increasing the ratio of the aqueous phase, the morphology could be continuously tuned from nanoplates to nanospindles with the (001) facets gradually disappearing. A fundamental understanding of the shape evolution was obtained via a series of characterizations including X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy.The NO 3 À ions and NH 3 molecules played vital parts at increased temperatures, not only in the phase structure of the iron oxide, but also in the formation of different hematite morphologies with different properties. The decrease in the photocatalytic efficiency in the visible region with the change from nanoplates to nanospindles under the same conditions indicated that the increase in the number of exposed (001) facets promoted the photocatalytic performance. The magnetic and electrochemical properties of typical morphologies were investigated and showed the potential applications of the nanostructures in various fields. Time-dependent morphology and structural evolution of a-Fe 2 O 3 nanodrumsTo indicate the formation process and growth mechanism of the hematite nanodrums (sample S3), a detailed study of the Fig. 1 (a) XRD patterns and (b) FTIR spectra of typical samples.This journal is

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“…In fact, such morphological features have a direct influence on charge carrier separation, lifetime and density which are critical issues for photo-activated hydrogen production and gas sensing [1,3,4,11,21,22]. The synthesis of hematite nanostructures has been carried out by several physical and chemical strategies, among which hydrothermal [10,16,[23][24][25] and solvothermal [26,27] methods, as well as chemical vapor deposition (CVD) [28][29][30], are amenable approaches to develop nanomaterials with controlled characteristics. In particular, the main CVD advantages are the high flexibility, high growth rate, good control of the reaction environment, excellent conformal step coverage, and adaptability to large scale processing, in contrast to synthetic techniques yielding conventional powdered materials [31].…”

mentioning

confidence: 99%

Tailoring iron(III) oxide nanomorphology by chemical vapor deposition: Growth and characterization

Peeters

Carraro

Maccato

et al. 2013

Physica Status Solidi (a)

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Iron(III) oxide nanosystems are actually the focus of an intensive attention due to their low cost, non‐toxicity, ample abundance, and attractive chemico‐physical properties. In this work, iron(III) oxide nanomaterials were deposited by chemical vapor deposition (CVD) under O2 atmospheres in the temperature range 500–800 °C, starting from the scarcely investigated tris(tert‐butyl acetoacetato)iron(III) precursor. All nanodeposits were found to consist of the α‐Fe2O3 (hematite) polymorph. Surface and in‐depth analyses demonstrated the presence of high purity Fe2O3, indicating the occurrence of a clean precursor decomposition under the adopted conditions. Interestingly, the system morphology could be controlled by varying the deposition temperature and ranged from the circular assembly of ordered nanosheets, to rough vortices, up to dense deposits characterized by the copresence of nanosheets and nanocolumns. The unique surface features offer great properties for advanced applications in various technological fields, such as catalysis and photocatalysis, solid state gas sensing, and magnetic recording media.

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Periodical structural conversion and its mechanism in hematite: from nanospindles, to nanotubes, to nanotires

Cited by 21 publications

References 50 publications

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe₂O₃@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe₂O₃@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Effect of sequential morphology adjustment of hematite nanoplates to nanospindles on their properties and applications

Tailoring iron(III) oxide nanomorphology by chemical vapor deposition: Growth and characterization

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Periodical structural conversion and its mechanism in hematite: from nanospindles, to nanotubes, to nanotires

Cited by 21 publications

References 50 publications

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe2O3@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe2O3@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Effect of sequential morphology adjustment of hematite nanoplates to nanospindles on their properties and applications

Tailoring iron(III) oxide nanomorphology by chemical vapor deposition: Growth and characterization

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Product

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Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe₂O₃@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe₂O₃@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting