Enhanced photoelectrochemical water splitting of hematite multilayer nanowire photoanodes by tuning the surface state via bottom-up interfacial engineering

Tang, Pengyi; Xie, Haibing; Ros, Carles; Han, Lijuan; Biset‐Peiró, Martí; He, Yongmin; Kramer, Wesley W.; Pérez-Rodrı́guez, A.; Saucedo, Edgardo; Galán‐Mascarós, José Ramón; Andreu, Teresa; Morante, Joan Ramón; Arbiol, Jordi

doi:10.1039/c7ee01475a

Cited by 208 publications

(178 citation statements)

References 68 publications

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“…In Figure b, the WO 3 /α‐Fe 2 O 3 electrode basically shows higher photocurrent density than bare WO 3 or α‐Fe 2 O 3 . Specifically, the pure hematite electrode exhibits the onset potential of 0.86 V vs. RHE, which is comparable with reported values ,,. The combined effects of the flat band potential, surface states and activation energy of reaction lead to the lower onset potential on the single material WO 3 photoanode as compared to the bare α‐Fe 2 O 3 photoanode ( Supporting Information ).…”

Section: Resultssupporting

confidence: 89%

Synthesis of Tungsten Trioxide/Hematite Core‐Shell Nanoarrays for Efficient Photoelectrochemical Water Splitting

et al. 2018

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Hematite, with a band gap of 2.0∼2.2 eV suitable for visible light absorption, has emerged to be a promising photoanode material for photoelectrochemical (PEC) catalysis of the oxygen evolution reaction (OER). Herein, we proposed the design and fabrication of a WO3/α‐Fe2O3 core‐shell heterojunction structure, aiming at alleviating the severe mismatch between the relatively long light penetration depth and the extremely short holes diffusion length in α‐Fe2O3. The WO3 nanoarray underlayer is grown directly on the FTO substrate, serving as an effective electron transfer layer and additional light absorber. The α‐Fe2O3 layer is further prepared via spin‐coating and a subsequent calcination process as a thin and uniform shell. The loading amount was regulated with different spin coating times of the precursor. The optimized WO3/α‐Fe2O3 core‐shell nanoarrays display an excellent performance with lower onset potential of 0.65 V vs. RHE and increased photocurrent response of 1.29 mA cm−2 at 1.23 V vs. RHE, much superior than the pristine α‐Fe2O3 or WO3 photoanode. Characterizations demonstrate that both improved light absorption and formation of heterojunction account for the excellent performance. After coating a NiFe‐LDH co‐catalyst layer, the oxygen evolution reaction is further enhanced, and high stability is achieved, benefiting from the efficient charge carrier generation, promoted charge separation in the semiconductor and the rapid consumption of holes for surface reaction.

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Section: Resultssupporting

confidence: 89%

Synthesis of Tungsten Trioxide/Hematite Core‐Shell Nanoarrays for Efficient Photoelectrochemical Water Splitting

et al. 2018

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“…The coating of the Fe 2 O 3 nanowire core by the pseudobrookite shell can be seen in Figure d–f, deduced from the HRTEM image in Figure b and the corresponding fast‐Fourier‐transform (FFT) spectrum in Figure c. As demonstrated in Ref. , this atomic layer can effectively suppress the charge recombination at the semiconductor junction interface, and the ITO underlayer enhances the electrical conductivity of the photoanodes, resulting in a higher photocurrent density and an enhanced fill factor. The OER performance can be promoted by using FeNiOOH nanodots (Figure b and Figure S1, Supporting Information), which were deposited on the nanowire surface by photo‐electrodeposition.…”

Section: Resultsmentioning

confidence: 99%

“…For the latter, we optimized the absorber layer sequence to reach the best photocurrent–photovoltage tradeoff upon coupling with the hematite absorber. The photoanode was composed of an indium‐doped tin oxide (ITO) underlayer with Fe 2 O 3 nanowires coated with a Fe 2 TiO 5 (pseudobrookite) atomic layer and decorated with FeNiOOH nanodots, as reported recently by Tang et al . By this integrated “one‐chip” tandem approach, we circumvent the need for a counter electrode, which is physically separated from the photoelectrode and usually composed of expensive materials .…”

Section: Introductionmentioning

confidence: 99%

Multilayered Hematite Nanowires with Thin‐Film Silicon Photovoltaics in an All‐Earth‐Abundant Hybrid Tandem Device for Solar Water Splitting

et al. 2019

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The concept of hybrid tandem device structures that combine metal oxides with thin‐film semiconducting photoabsorbers holds great promise for large‐scale, robust, and cost‐effective bias‐free photoelectrochemical water splitting (PEC‐WS). This work highlights important steps toward the efficient coupling of high‐performance hematite photoanodes with multijunction thin‐film silicon photocathodes providing high bias‐free photocurrent density. The hybrid PEC‐WS device is optimized by testing three types of multijunction silicon photocathodes with the hematite photoanode: amorphous silicon (a‐Si:H) tandem: a‐Si:H/a‐Si:H and triple junction with microcrystalline silicon (μc‐Si:H): a‐Si:H/a‐Si:H/μc‐Si:H and a‐Si:H/μc‐Si:H/μc‐Si:H. The results provide evidence that the multijunction structures offer high flexibility for hybrid tandem devices with regard to tunable photovoltages and spectral matching. Furthermore, both photoanode and photocathode are tested under various electrolyte and light concentration conditions, respectively, with respect to their photoelectrochemical performance and stability. A 27 % enhancement in the solar‐to‐hydrogen conversion efficiency is observed upon concentrating light from 100 to 300 mW cm−2. Ultimately, bias‐free water splitting is demonstrated, with a photocurrent density of 4.6 mA cm−2 (under concentrated illumination) paired with excellent operation stability for more than 24 h of the all‐earth‐abundant and low‐cost hematite/silicon tandem PEC‐WS device.

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“…To further evaluate charge transfer kinetics of those photoanodes, the charge transfer efficiency is induced, which can be estimated through the following equation

Transfer efficiency (%) = \frac{k_{ct}}{k_{ct} + k_{rec}} = \frac{R_{rec}}{R_{ct, trap} + R_{rec}}

where k ct and k rec represent the charge transfer and trapping rate constants, respectively. Figure c displays the charge transfer efficiency obtained from PEIS data.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO₃⁻/CO₂ System

Cai

Yang

Liu

et al. 2019

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Photoelectrochemical carbon dioxide conversion to fuels such as carbon monoxide, methanol, and ethylene exhibits great potential to solve energy issues. Unfortunately, CO2 conversion efficiency is still low due to violent charge recombination at the photoanode. Herein, a novel 3D macroporous ferroelectric heterojunction composed of BiFeO3 and LiNbO3 is developed by a template‐assisted sol–gel method, aiming at facilitating charge transfer kinetics. As expected, a tremendous enhancement of photocurrent density (300 times vs bare planar BiFeO3 film) and charge transfer efficiency (up to 76%) is obtained in the HCO3−/CO2 system without any cocatalyst. The photoelectrochemical performance is switchable by poling to form a depolarization electric field. Photoelectrochemical impedance spectroscopy reveals that the charge transfer resistance decreases due to the synergistic effect of BiFeO3 3D macroporous skeleton and LiNbO3 passivation layer by tuning surface states. These results suggest a novel strategy for enhancing photoelectrochemical water oxidation as the anodic reaction of CO2 reduction.

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Enhanced photoelectrochemical water splitting of hematite multilayer nanowire photoanodes by tuning the surface state via bottom-up interfacial engineering

Abstract: Tuning the donor density and the surface state density of hematite multilayer nanowire photoanodes.

Cited by 208 publications

References 68 publications

Synthesis of Tungsten Trioxide/Hematite Core‐Shell Nanoarrays for Efficient Photoelectrochemical Water Splitting

Synthesis of Tungsten Trioxide/Hematite Core‐Shell Nanoarrays for Efficient Photoelectrochemical Water Splitting

Multilayered Hematite Nanowires with Thin‐Film Silicon Photovoltaics in an All‐Earth‐Abundant Hybrid Tandem Device for Solar Water Splitting

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO₃⁻/CO₂ System

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Enhanced photoelectrochemical water splitting of hematite multilayer nanowire photoanodes by tuning the surface state via bottom-up interfacial engineering

Abstract: Tuning the donor density and the surface state density of hematite multilayer nanowire photoanodes.

Cited by 208 publications

References 68 publications

Synthesis of Tungsten Trioxide/Hematite Core‐Shell Nanoarrays for Efficient Photoelectrochemical Water Splitting

Synthesis of Tungsten Trioxide/Hematite Core‐Shell Nanoarrays for Efficient Photoelectrochemical Water Splitting

Multilayered Hematite Nanowires with Thin‐Film Silicon Photovoltaics in an All‐Earth‐Abundant Hybrid Tandem Device for Solar Water Splitting

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO3−/CO2 System

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Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO₃⁻/CO₂ System