Ultrathin-layer α-Fe2O3 deposited under hematite for solar water splitting

Bouhjar, Feriel; Bessaı̈s, B.; Marı́, B.

doi:10.1007/s10008-018-3946-7

Cited by 20 publications

(12 citation statements)

References 31 publications

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“…As a result of this process, crystalline anode iron oxide Fe 2 O 3 is obtained on the iron surface [22]. The formation of iron oxide in the amorphous form is typical for the anodization process and occurs even during the preparation of ultra-thin layers [23]. A similar effect in the formation of a mixture of oxides was observed during the anodization of an intermetallic FeAl phase [10].…”

Section: Resultsmentioning

confidence: 99%

Formation of Nanoporous Mixed Aluminum-Iron Oxides by Self-Organized Anodizing of FeAl3 Intermetallic Alloy

2019

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Nanostructured anodic oxide layers on an FeAl3 intermetallic alloy were prepared by two-step anodization in 20 wt% H2SO4 at 0 °C. The voltage range was 10.0–22.5 V with a step of 2.5 V. The structural and morphological characterizations of the received anodic oxide layers were performed by field emission scanning electron microscopy (FE-SEM). Therefore, the formed anodic oxide was found to be highly porous with a high surface area, as indicated by the FE-SEM studies. It has been shown that the morphology of fabricated nanoporous oxide layers is strongly affected by the anodization potential. The oxide growth rate first increased slowly (from 0.010 μm/s for 10 V to 0.02 μm/s for 15 V) and then very rapidly (from 0.04 μm/s for 17.5 V up to 0.13 μm/s for 22.5 V). The same trend was observed for the change in the oxide thickness. Moreover, for all investigated anodizing voltages, the structural features of the anodic oxide layers, such as the pore diameter and interpore distance, increased with increasing anodizing potential. The obtained anodic oxide layer was identified as a crystalline FeAl2O4, Fe2O3 and Al2O3 oxide mixture.

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Section: Resultsmentioning

confidence: 99%

Formation of Nanoporous Mixed Aluminum-Iron Oxides by Self-Organized Anodizing of FeAl3 Intermetallic Alloy

2019

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“…The layer of hematite that covers the FTO acts as a blocking layer to reduce the back injection of electrons from the FTO. Therefore, holes can reach the surface more efficiently and participate in oxygen evolution reaction [36,42,64,65]. Here we use a thin film of metallic iron coated on FTO that can be fully converted into an iron oxide/hydroxide layer by cyclic voltammetry.…”

Section: Discussionmentioning

confidence: 99%

“…In this work, by annealing the samples at 775 • C, the onset potential in J-V curve of hematite with TiO 2 layer shifts to more positive potential, and the current density increases from 0.21 mA/cm 2 to 0.35 mA/cm 2 at 1.4 V vs. RHE. Feriel et al electrodeposited 40 nm to 60 nm hematite on FTO, underneath a hydrothermally fabricated hematite photoanode, and found an increase in the photoelectrochemical properties [42]. Cho et al added 40 nm dense layer of different materials, such as SnO 2 and Fe 2 O 3 -Ti, between hematite and the FTO substrate, which shifted the dark current onset potential to more positive values and also increased the current density [36].…”

Section: Introductionmentioning

confidence: 99%

Fe2O3 Blocking Layer Produced by Cyclic Voltammetry Leads to Improved Photoelectrochemical Performance of Hematite Nanorods

et al. 2019

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Hematite is a low band gap, earth abundant semiconductor and it is considered to be a promising choice for photoelectrochemical water splitting. However, as a bulk material its efficiency is low because of excessive bulk, surface, and interface recombination. In the present work, we propose a strategy to prepare a hematite (α-Fe2O3) photoanode consisting of hematite nanorods grown onto an iron oxide blocking layer. This blocking layer is formed from a sputter deposited thin metallic iron film on fluorine doped tin oxide (FTO) by using cyclic voltammetry to fully convert the film into an anodic oxide. In a second step, hematite nanorods (NR) are grown onto the layer using a hydrothermal approach. In this geometry, the hematite sub-layer works as a barrier for electron back diffusion (a blocking layer). This suppresses recombination, and the maximum of the incident photon to current efficiency is increased from 12% to 17%. Under AM 1.5 conditions, the photocurrent density reaches approximately 1.2 mA/cm2 at 1.5 V vs. RHE and the onset potential changes to 0.8 V vs. RHE (using a Zn-Co co-catalyst).

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“…[1] Among other compounds, hematite (α-Fe 2 O 3 ) has claimed attention as a photoanode for producing the oxygen evolution reaction (OER) because of its low cost, stability in contact with alkaline solutions, n-type semiconducting properties and band gap of around 2.0 eV. Processes catalyzed by hematite include oxygen reduction reaction (ORR), [2][3][4][5] photoelectrochemical water splitting, [6][7][8][9][10][11] and hydrogen peroxide oxidation. [12] The electrochemistry of hematite has been widely studied.…”

Section: Introductionmentioning

confidence: 99%

Hematite as an Electrocatalytic Marker for the Study of Archaeological Ceramic Clay bodies: A VIMP and SECM Study**

Doménech‐Carbó

Giannuzzi

Mangone³

et al. 2021

ChemElectroChem

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The electrocatalytic effect exerted by hematite, a ubiquitous component of clay bodies, on the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) can be used to acquire information on archaeological ceramics. The solid-state voltammetric response of different hematite and ochre specimens, accompanied by SECM analysis in contact with 0.10 M HCl aqueous solution, is described. In air-saturated solutions, catalytic effects on the ORR and OER are accompanied by Fe(III)/Fe(II) and Fe(IV)/Fe(III) redox reactions. Such processes are conditioned by a variety of factors, the hydroxylation degree of the mineral surfaces being particularly influential, and exhibit significant variations upon heating the specimens between 300 and 900 °C. Voltammetric measurements carried out on a set of archaeological samples of Apulian red-figured pottery dated back within 5 th and 4 th centuries BCE permit to obtain sitecharacteristic voltammetric profiles.

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Ultrathin-layer α-Fe2O3 deposited under hematite for solar water splitting

Cited by 20 publications

References 31 publications

Formation of Nanoporous Mixed Aluminum-Iron Oxides by Self-Organized Anodizing of FeAl3 Intermetallic Alloy

Formation of Nanoporous Mixed Aluminum-Iron Oxides by Self-Organized Anodizing of FeAl3 Intermetallic Alloy

Fe2O3 Blocking Layer Produced by Cyclic Voltammetry Leads to Improved Photoelectrochemical Performance of Hematite Nanorods

Hematite as an Electrocatalytic Marker for the Study of Archaeological Ceramic Clay bodies: A VIMP and SECM Study**

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