Identifying champion nanostructures for solar water-splitting

Warren, Scott C.; Voïtchovsky, Kislon; Dotan, Hen; Leroy, Céline M.; Cornuz, Maurin; Stellacci, Francesco; Hébert, C.; Rothschild, Avner; Grätzel, Michaël

doi:10.1038/nmat3684

Cited by 527 publications

(491 citation statements)

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“…Compared with the diurnal‐worked solar cells, inspired from the photosynthesis in nature, the technologies such as solar‐driven photoelectrochemical (PEC) water splitting or reduction of CO 2 whose working principle is to convert solar energy to chemical bonds that can be stored and off‐hour used have provided another anticipated possibility to capture the sunlight 1. A lot of materials have been employed as photoelectrodes in PEC cells, among which the α‐Fe 2 O 3 (also called hematite) is widely acknowledged as a promising candidate due to its earth‐abundant element component, physical and chemical stability, and wide spectrum absorption range in visible light region 2. Although the theoretical solar‐to‐hydrogen (STH) efficiency of hematite can reach to 15% if incorporate with a proper tandem photovoltaic (PV) setup,3 the performance of the state‐of‐the‐art hematite based photoelectrode is far from the idealized model, owing to the intrinsic adverse factors such as poor electrical conducting ability, restricted hole diffusion length (<5 nm), low absorption coefficient, and low flat‐band potential in water splitting.…”

Section: Introductionmentioning

confidence: 99%

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl₄ Treated 3D Antimony‐Doped SnO₂ Macropore/Branched α‐Fe₂O₃ Nanorod Heterojunction Photoanode

Rao

Chen

et al. 2015

Advanced Science

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Utilizing photoelectrochemical (PEC) cells to directly collecting solar energy into chemical fuels (e.g., H2 via water splitting) is a promising way to tackle the energy challenge. α‐Fe2O3 has emerged as a desirable photoanode material in a PEC cell due to its wide spectrum absorption range, chemical stability, and earth abundant component. However, the short excited state lifetime, poor minority charge carrier mobility, and long light penetration depth hamper its application. Recently, the elegantly designed hierarchical macroporous composite nanomaterial has emerged as a strong candidate for photoelectrical applications. Here, a novel 3D antimony‐doped SnO2 (ATO) macroporous structure is demonstrated as a transparent conducting scaffold to load 1D hematite nanorod to form a composite material for efficient PEC water splitting. An enormous enhancement in PEC performance is found in the 3D electrode compared to the controlled planar one, due to the outstanding light harvesting and charge transport. A facile and simple TiCl4 treatment further introduces the Ti doping into the hematite while simultaneously forming a passivation layer to eliminate adverse reactions. The results indicate that the structural design and nanoengineering are an effective strategy to boost the PEC performance in order to bring more potential devices into practical use.

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Section: Introductionmentioning

confidence: 99%

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl₄ Treated 3D Antimony‐Doped SnO₂ Macropore/Branched α‐Fe₂O₃ Nanorod Heterojunction Photoanode

Rao

Chen

et al. 2015

Advanced Science

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“…[1][2][3][4][5] Since 1972, when the pioneering work on PEC water splitting was reported by Fujishima and Honda, 6 a wide range of materials has been investigated. In fact, semiconductor materials such as TiO 2 , SrTiO 3 , WO 3 , ZnO, BiVO 4 and Cu(In,Ga)Se 2,3,4,[7][8][9][10] have been used for the development of photoanodes in PEC cells.Compared to these materials, α-Fe 2 O 3 (hematite), has a narrower band-gap (1.9-2.2 eV), which allows to harvest up to 40% of the incident solar radiation. Furthermore, α-Fe 2 O 3 is a promising semiconducting material for photoelectrochemical and photocatalysis applications due to its stability, abundance and environmental compatibility, as well as convenient position of the valence band.…”

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confidence: 99%

“…[1][2][3][4][5] Among many methods, solar hydrogen generation by photoelectrochemical (PEC) water splitting is a particularly attractive one because of the environmental friendless and the abundance of water and solar energy without emission of pollutants. [1][2][3][4][5] Since 1972, when the pioneering work on PEC water splitting was reported by Fujishima and Honda, 6 a wide range of materials has been investigated. In fact, semiconductor materials such as TiO 2 , SrTiO 3 , WO 3 , ZnO, BiVO 4 and Cu(In,Ga)Se 2,3,4,[7][8][9][10] have been used for the development of photoanodes in PEC cells.…”

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confidence: 99%

“…Nanostructured are thus highly attractive morphologies for enabling a high photon harvesting efficiency with hematite 30 by decreasing electron-hole recombination. Following this nanostructuring strategy, several attempts can be encountered in the literature for preparing nanostructured hematite thin films with ultrahigh surface roughness, 3,30 hematite nanorods and nanowires, 31 and nanotubes. 26,27,31,32 In this sense it must be pointed out that because the electrical conductivity of hematite is highly anisotropic, 26 charge transport is hindered at the interfaces between the crystallites with different crystallographic orientations.…”

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confidence: 99%

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Electrochemically Grown Self-Organized Hematite Nanotube Arrays for Photoelectrochemical Water Splitting

Schrebler

Ballesteros

Gómez

et al. 2014

J. Electrochem. Soc.

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Hematite nanostructures were electrochemically grown by ultrasound-assisted anodization of iron substrates in an ethylene glycol based medium. These hematite nano-architectures can be tuned from a 1-D nanoporous layer to a self-organized nanotube one if the grown is done onto a bare iron foil substrate or onto an electrochemical pretreated one, respectively. Depending upon the pre-treatment conditioning, the self-organized nanotube layer consists of nanotube arrays with a single tube inner diameter of approximately 40-50 nm and wall thickness of 20-30 nm. Their morphological, structural and optoelectronic properties are studied. The photoelectrochemical properties of the resulting hematite nanostructures are studied from the point of view of their application as photoanodes in splitting of water. Through the photocurrent transients for the three nanostructured hematite type electrodes under study, the rate constants k tr and k rec corresponding to the rate constant of charge transfer and recombination processes have been determined. In all cases, the potential value where k tr > k rec was attained at more negative values than the reversible potential of water oxidation, indicating a photocatalytic effect. All samples show a maximum IPCE value between 350 and 375 nm, being the samples pretreated at −1.0 V which shows the highest IPCE value: 45% at 375 nm. In the last years, hydrogen energy has found increased attention as a renewable and clean energy source.1-5 Among many methods, solar hydrogen generation by photoelectrochemical (PEC) water splitting is a particularly attractive one because of the environmental friendless and the abundance of water and solar energy without emission of pollutants. [1][2][3][4][5] Since 1972, when the pioneering work on PEC water splitting was reported by Fujishima and Honda, 6 a wide range of materials has been investigated. In fact, semiconductor materials such as TiO 2 , SrTiO 3 , WO 3 , ZnO, BiVO 4 and Cu(In,Ga)Se 2,3,4,[7][8][9][10] have been used for the development of photoanodes in PEC cells.Compared to these materials, α-Fe 2 O 3 (hematite), has a narrower band-gap (1.9-2.2 eV), which allows to harvest up to 40% of the incident solar radiation. Furthermore, α-Fe 2 O 3 is a promising semiconducting material for photoelectrochemical and photocatalysis applications due to its stability, abundance and environmental compatibility, as well as convenient position of the valence band. 3,[11][12][13][14][15][16][17][18][19][20][21][22][23] In spite of the good properties presented by the α-Fe 2 O 3 , several problems must be solved in order to convert this material in an optimal one for certain applications. For instance, two of these problems correspond to: i) the very short hole diffusion length (20 nm, 24 2-4 nm) 25 compared to the light penetration depth (α −1 = 118 nm at λ = 550 nm), which results in the rapid non-radiative electron-hole recombination inside the semiconductor, and ii) poor electrical conductivity. [26][27][28] Two approaches have been taken to tackle the shor...

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“…1,3,7,10 It is believed that nanostructured materials can provide beneficial effects including quantum dot sensitisation, band structural modification, the domination of crystal facets and plasmonic association. Therefore, to develop better photoelectrodes and more efficient PEC and PV devices, one of the main strategies is nanostructuring by exploiting scaling laws and specific effects at the nanoscale to enhance the efficiency of existing semiconductors and metal oxides.…”

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confidence: 99%

Branched nanostructures for photoelectrochemical water splitting

Mao¹

2014

Nanomaterials and Energy

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IntroductionSunlight is a free, non-polluting and abundant renewable source of clean energy. The amount of solar energy that strikes the Earth yearly is ~10,000 times the total energy that is consumed on our planet. Converting solar energy into other easily usable forms has attracted considerable interest in the last several decades. Among different solar energy conversion technologies, photoelectrolysis has the ability to split water through solar energy to produce hydrogen (a chemical fuel) without any emission of by-products.1-6 The demonstration of metal oxides as photoanodes for photoelectrochemical (PEC) water splitting was pioneered in 1972 by However, the conversion efficiency today remains unsatisfactory, even lower than that of photovoltaics (PVs), and is limited mainly by the low performance of PEC electrodes. An efficient PEC cell requires electrode materials that can provide rapid charge transfer at the electrode/electrolyte interface, long-term stability and efficient harvesting of a wide range of the solar spectrum, and that are low-cost and non-toxic as well. In the last several decades, however, no breakthroughs on PEC electrode materials have been achieved yet in either the material design of photoelectrode or material stability. 10With recent advances in nanoscience and nanotechnology, nanomaterials and their designs should be promising candidates for constructing photoelectrodes because of their extremely small feature size, large surface area, large surface-to-volume ratio and short diffusion length for carrier transport. 1,3,7,10 It is believed that nanostructured materials can provide beneficial effects including quantum dot sensitisation, band structural modification, the domination of crystal facets and plasmonic association. Therefore, to develop better photoelectrodes and more efficient PEC and PV devices, one of the main strategies is nanostructuring by exploiting scaling laws and specific effects at the nanoscale to enhance the efficiency of existing semiconductors and metal oxides. As a result, there has been intensive research directed worldwide by taking advantages of nanomaterials to make PEC devices with higher solar-to-hydrogen conversion efficiency.It is well known that specific surface area, defined by surface-tovolume ratio, depends on feature size and geometry. The surface-tovolume ratio is, to a first-order approximation, inversely proportional to the feature size as 1/r.11 Highly symmetric objects, such as spheres, have low specific surface area. With equal volume, a rod has a larger surface-to-volume ratio than a spherical particle, and

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Identifying champion nanostructures for solar water-splitting

Cited by 527 publications

References 50 publications

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl₄ Treated 3D Antimony‐Doped SnO₂ Macropore/Branched α‐Fe₂O₃ Nanorod Heterojunction Photoanode

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl₄ Treated 3D Antimony‐Doped SnO₂ Macropore/Branched α‐Fe₂O₃ Nanorod Heterojunction Photoanode

Electrochemically Grown Self-Organized Hematite Nanotube Arrays for Photoelectrochemical Water Splitting

Branched nanostructures for photoelectrochemical water splitting

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Identifying champion nanostructures for solar water-splitting

Cited by 527 publications

References 50 publications

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl4 Treated 3D Antimony‐Doped SnO2 Macropore/Branched α‐Fe2O3 Nanorod Heterojunction Photoanode

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl4 Treated 3D Antimony‐Doped SnO2 Macropore/Branched α‐Fe2O3 Nanorod Heterojunction Photoanode

Electrochemically Grown Self-Organized Hematite Nanotube Arrays for Photoelectrochemical Water Splitting

Branched nanostructures for photoelectrochemical water splitting

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Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl₄ Treated 3D Antimony‐Doped SnO₂ Macropore/Branched α‐Fe₂O₃ Nanorod Heterojunction Photoanode

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl₄ Treated 3D Antimony‐Doped SnO₂ Macropore/Branched α‐Fe₂O₃ Nanorod Heterojunction Photoanode