Unassisted photoelectrochemical water splitting beyond 5.7% solar-to-hydrogen conversion efficiency by a wireless monolithic photoanode/dye-sensitised solar cell tandem device

Shi, Xinjian; Zhang, Kan; Shin, Kahee; Ma, Ming; Kwon, Jeong-Yi; Choi, In Taek; Kim, Jung Kyu; Kim, Hwan Kyu; Wang, Dong Hwan; Park, Jae Hyung

doi:10.1016/j.nanoen.2015.02.018

Cited by 141 publications

(97 citation statements)

References 28 publications

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“…67% by reflection losses at the air/SiO 2 /KOH/NiO x / SiO 2 /Si interfaces. [44][45][46][47] Thus, the incoming photon flux is [5] as the maximum attainable photocurrent density. This is in agreement with the obtained results, confirming that most of the incoming light can be used for the OER if the necessary overpotential is applied.…”

Section: Results and Discussion -Electrochemistrymentioning

confidence: 99%

“…The obtained results can then be applied to further optimize devices based on multijunction solar cells. [2][3][4][5][6] …”

mentioning

confidence: 99%

“…The obtained results can then be applied to further optimize devices based on multijunction solar cells. [2][3][4][5][6] Especially in the last few years, there have been a lot of great accomplishments in this direction. McDowell and Hu 7,8 investigated the performance of n-Si | TiO 2 heterojunctions and TiO 2 covered np + homojunctions with an additional Ni catalyst, achieving good long term stability.…”

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confidence: 99%

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The Impact of Different Si Surface Terminations in the (001) n-Si/NiOx Heterojunction on the Oxygen Evolution Reaction (OER) by XPS and Electrochemical Methods

Tengeler

Fingerle

Calvet

et al. 2018

J. Electrochem. Soc.

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The interaction between (001) n-Si and NiO x was investigated with regard to the oxygen evolution reaction (OER), applicable either for water splitting or CO 2 reduction. Thin layers of nickel oxide were deposited step by step by reactive sputter deposition and analyzed in-situ after each step using X-ray photoelectron spectroscopy (XPS). This was performed for silicon with different surface preparations: H-termination, thermally grown oxide (2 Å) and a monolayer of native oxide (4 Å). Upon contact formation the initial flatband like situation in the Si substrates changed to a 0.35 to 0.4 eV upward band bending for all three heterojunctions, with an alignment of the valence bands favorable to hole extraction. With near identical heterojunction performance and identical NiO x catalyst layers (η(10 mA/cm 2 ) = 0.44 ± 0.01 V vs. RHE on Ni) an equally identical performance for the OER would be expected. While the native oxide covered sample shows the expected performance in cyclic voltammetry measurements the others fall short of expectations. Using chopped light measurements, this under-performance could be attributed to a higher density of defect states at the silicon surface. Apparently a 4Å SiO 2 layer is sufficient protection to prevent the formation of defect states during NiO x deposition, thinner protective layers or none at all result in increased defect states, while thicker layers perform poorly due to their high resistance. Direct photoelectrochemical devices are an exciting approach to the storage of renewable energies. Depending on the preferred energy cycle they can be used either for water splitting or CO 2 reduction, in the end it is only a question of the employed catalysts and necessary overpotentials. A direct photoelectrochemical device has two main functional parts, which do not necessarily have to be physically separate. First, there is the photoabsorber, basically a solar cell, who has to supply the necessary photovolage U ph and photocurrent J ph to power the desired redox reaction. Second, the catalytic surface, which is in direct contact with the electrolyte and should be catalytically active, thus allowing high current densities at low overpotentials η. In an ideal case the total device performance should be a result of those two contributions only.Initial research on water splitting was focused on a single semiconducting material performing well in both functions. This was first demonstrated on a TiO 2 electrode by Fujishima and Honda in 1972. 1 In such a device the photoabsorber functionality is defined by the interface junction between semiconductor and electrolyte. Investigated materials were mostly wide bandgap materials, as they could, in theory, provide the necessary U ph .However, the double function of the semiconductor electrolyte interface makes an evaluation of such devices difficult, as it is hard to determine whether a lack of performance is a result from poor current voltage (IE) behavior of the junction or the poor catalytic performance of the material. Furthermore, t...

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Section: Results and Discussion -Electrochemistrymentioning

confidence: 99%

“…The obtained results can then be applied to further optimize devices based on multijunction solar cells. [2][3][4][5][6] …”

mentioning

confidence: 99%

mentioning

confidence: 99%

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The Impact of Different Si Surface Terminations in the (001) n-Si/NiOx Heterojunction on the Oxygen Evolution Reaction (OER) by XPS and Electrochemical Methods

Tengeler

Fingerle

Calvet

et al. 2018

J. Electrochem. Soc.

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“…Photoelectrochemical (PEC) hydrogen production through solar water splitting is considered as a promising approach for clean hydrogen fuel generation [1][2][3][4][5][6][7][8], which has potential for high solar-to-hydrogen (STH) efficiencies of over 30% [9]. Obtaining a PEC tandem cell (full PEC device/system) in a Z-scheme configuration to handle efficient and durable overall spontaneous solar water splitting is challenging.…”

Section: Introductionmentioning

confidence: 99%

Nanowire/nanotube array tandem cells for overall solar neutral water splitting

et al. 2016

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In this study, we report the fabrication and characterization of a novel PEC tandem cell, consisting of p-Si/TiO 2 /Fe 2 O 3 core/shell/hierarchical nanowire (csh-NW) array photocathode and TiO 2 /TiO 2 core/shell nanotube (cs-NT) array photoanode, for overall solar water splitting in a neutral pH water. The p-Si/n-TiO 2 /n-Fe 2 O 3 csh-NWs, made mainly by solution-processed methods, offer significantly improved performance in the neutral pH water with a low (positive) onset potential and photoactivity at zero bias, due to the increased reaction surface area, effective energy band alignment among p-Si, n-TiO 2 and n-Fe 2 O 3 enhancing the charge separation, improved optical absorption, and enhanced gas evolution. Nitrogen modification (annealing under N 2 ) is used to further enhance the csh-NWs photocathodic performance. The PEC tandem cell is then able to handle overall solar water splitting in the neutral pH water with a solar-to-hydrogen (STH) efficiency of $ 0.18%. The achieved results demonstrate initial steps toward the realization of full PEC devices using earth-abundant materials for solar hydrogen generation suggesting competitive performance when solar matched photoanode core material and co-catalysts are used.

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“…Since the design of a tandem cell configuration for water splitting was first proposed123, a variety of studies have been reported45, and various photoanode46/photovoltaic578910111213 combinations have been tested to optimize the performance and efficiency. For example, Shi et al .…”

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Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling

et al. 2016

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Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation.

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Unassisted photoelectrochemical water splitting beyond 5.7% solar-to-hydrogen conversion efficiency by a wireless monolithic photoanode/dye-sensitised solar cell tandem device

Cited by 141 publications

References 28 publications

The Impact of Different Si Surface Terminations in the (001) n-Si/NiOx Heterojunction on the Oxygen Evolution Reaction (OER) by XPS and Electrochemical Methods

The Impact of Different Si Surface Terminations in the (001) n-Si/NiOx Heterojunction on the Oxygen Evolution Reaction (OER) by XPS and Electrochemical Methods

Nanowire/nanotube array tandem cells for overall solar neutral water splitting

Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling

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