Hematite (α-Fe2O3) is one of the most promising photoanode materials for photoelectrochemical (PEC) water splitting although great challenges hinder high performance. Silicon-doped α-Fe2O3 shows improved PEC activity but the relationship among dopant content and enhanced conductivity, structure, and particle morphology is only poorly understood. Here, we present a systematic study on hydrothermally grown α-Fe2O3 nanocrystals by using XRD, Raman, UV–vis spectroscopy, TEM, XPS, SQUID magnetometry, electrochemical impedance spectroscopy, and photocurrent measurements. We find that the Si content controls the morphology of α-Fe2O3 already at Si 5 at.% inducing a transition from nanostructures with ellipsoidal shape to nanowires. Si doping is effective in improving PEC activity in the case of Si1% at. sample, which shows a 20% photocurrent enhancement in comparison with pure α-Fe2O3. On the contrary, α-Fe2O3 containing Si content higher than 5 at.% presents lower PEC activity. Results are rationalized in the view of the interplay of morphological, structural, magnetic, and electronic properties in doped α-Fe2O3 thus providing general guidelines for the design of efficient photoelectrodes for solar water splitting.

Shaped‐controlled silicon‐doped hematite nanostructures for enhanced PEC water splitting / M. Allieta, M. Marelli, F. Malara, C.L. Bianchi, S. Santangelo, C. Triolo, S. Patane, A.M. Ferretti, Š. Kment, A. Ponti, A. Naldoni. - In: CATALYSIS TODAY. - ISSN 0920-5861. - (2018 Oct 23). [Epub ahead of print] [10.1016/j.cattod.2018.10.010]

Shaped‐controlled silicon‐doped hematite nanostructures for enhanced PEC water splitting

M. Marelli;C.L. Bianchi;
2018-10-23

Abstract

Hematite (α-Fe2O3) is one of the most promising photoanode materials for photoelectrochemical (PEC) water splitting although great challenges hinder high performance. Silicon-doped α-Fe2O3 shows improved PEC activity but the relationship among dopant content and enhanced conductivity, structure, and particle morphology is only poorly understood. Here, we present a systematic study on hydrothermally grown α-Fe2O3 nanocrystals by using XRD, Raman, UV–vis spectroscopy, TEM, XPS, SQUID magnetometry, electrochemical impedance spectroscopy, and photocurrent measurements. We find that the Si content controls the morphology of α-Fe2O3 already at Si 5 at.% inducing a transition from nanostructures with ellipsoidal shape to nanowires. Si doping is effective in improving PEC activity in the case of Si1% at. sample, which shows a 20% photocurrent enhancement in comparison with pure α-Fe2O3. On the contrary, α-Fe2O3 containing Si content higher than 5 at.% presents lower PEC activity. Results are rationalized in the view of the interplay of morphological, structural, magnetic, and electronic properties in doped α-Fe2O3 thus providing general guidelines for the design of efficient photoelectrodes for solar water splitting.
Hematite; Hydrothermal synthesis; Semiconductor; Substitutional doping; Water splitting; Catalysis; Chemistry (all)
Settore CHIM/04 - Chimica Industriale
23-ott-2018
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/598728
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