Protection of Si photocathode using TiO2 deposited by high power impulse magnetron sputtering for H2 evolution in alkaline media

Bae, Dowon; Shayestehaminzadeh, S.; Thorsteinsson, Einar B.; Pedersen, Thomas; Hansen, Ole; Seger, Brian; Vesborg, Peter Christian Kjærgaard; Ólafsson, S.

doi:10.1016/j.solmat.2015.10.020

Cited by 56 publications

(72 citation statements)

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“…The 635 nm cut‐off filter was used to simulate the red part of the solar spectrum under the assumption that the Si is used as a bottom cell in a tandem water splitting device. Figure a shows an initial degradation during the first day, which is likely due to adsorption of impurities,, and then no noticeable signs of further degradation in photocurrent ( J ph ) for the following 40 days. However, once the electrode was subjected to cycling in a 12 hour on/12 hour off manner, a significant instability in the photocurrent emerges.…”

Section: Figurementioning

confidence: 66%

“…Thus experimental work is needed to accurately determine corrosion rates ,,. Works by Young and Bae et al., have shown that GaAs and Si, respectively, can be effectively protected at open circuit potential in the dark. However, cycling between two potentials can sometimes cause serious corrosion as exemplified by catalyst corrosion in the PEM fuel cells …”

Section: Figurementioning

confidence: 99%

“…The scanning electron microscopy (SEM) image (inset in Figure a) revealed that the surface of the photocathode is partly covered with a thick bright layer, while the TiO 2 in other areas is well preserved. The XPS spectra from the sample right after the Pt photodeposition ( via reduction of the Pt‐dihydrogen dinitrosulphatoplatinum (II) salt (Pt‐DNS, Johnson Matthey) as described in elsewhere),, and the XPS after the long‐term experiment (Figure a) shows no obvious peak from the elemental Si (99.4±0.3 eV) which corroborates the previous contention that Si is well protected by the TiO 2 . An interesting feature is that the carbon peak showed a drastic change after the long‐term experiment.…”

Section: Figurementioning

confidence: 99%

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Durability Testing of Photoelectrochemical Hydrogen Production under Day/Night Light Cycled Conditions

et al. 2018

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This work investigates long‐term photoelectrochemical hydrogen evolution (82 days) in 1 M HClO4 using a TiO2:H protected crystalline Si‐based photocathode with metal‐oxide‐semiconductor (MOS) junctions. It is shown that day/night cycling leads to relatively rapid performance degradation while the photocurrent under the continuous light condition is relatively stable. We observed that the performance loss is mainly due to contamination of the catalytically active surface with carbonaceous material. By ultraviolet (UV) light exposure, we also observed that the activity can be restored, most likely due to photocatalytic degradation of organic compounds by the UV light excited TiO2 protection layer.

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confidence: 66%

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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Durability Testing of Photoelectrochemical Hydrogen Production under Day/Night Light Cycled Conditions

et al. 2018

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“…[39][40][41][42] For instance, recent studies have reported interesting characteristics of ALD-TiO2 such as increased adhesion on Si photoanodes 43 or enhanced plasmonic resonance in photovoltaic devices 44 .Photocathodes protected with polycrystalline TiO2 have been widely reported as the conduction band alignment between the silicon and the TiO2 metal oxide facilitates the electron transfer from the photocathode to the electrolyte through the TiO2 layer that is n-type. 22,26,[45][46][47][48][49]…”

mentioning

confidence: 99%

“…Photocathodes protected with polycrystalline TiO2 have been widely reported as the conduction band alignment between the silicon and the TiO2 metal oxide facilitates the electron transfer from the photocathode to the electrolyte through the TiO2 layer that is n-type. 22,26,[45][46][47][48][49]…”

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Insight into the Degradation Mechanisms of Atomic Layer Deposited TiO₂ as Photoanode Protective Layer

Ros

Carretero

David

et al. 2019

ACS Appl. Mater. Interfaces

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Around 100 nm thick TiO2 layers deposited by atomic layer deposition (ALD) have been investigated as anticorrosion protective films for silicon based photoanodes decorated with 5 nm NiFe catalyst in highly alkaline electrolyte. Completely amorphous layers presented high resistivity, meanwhile the ones synthetized at 300ºC, having a fully anatase crystalline TiO2 structure, introduced insignificant resistance, showing direct correlation between crystallization degree and electrical conductivity. The conductivity through crystalline TiO2 layers has been found not to be homogeneous, presenting preferential conduction paths attributed to grain boundaries and defects within the crystalline structure. A correlation between the c-AFM measurements and grain interstitials can be seen, supported by HRTEM cross sectional images presenting defective regions in crystalline TiO2 grains. It was found that the conduction mechanism goes through the injection of electrons coming from water oxidation from the electrocatalyst into the TiO2 conduction band. Then, electrons are transported to the Si/SiOx/TiO2 interface where electrons recombine with holes given by the p + n-Si junction. No evidences of intra band gap states in TiO2 responsible of conductivity have been detected. Stability measurements of fully crystalline samples over 480 h in anodic polarization show a continuous current decay. Electrochemical impedance spectroscopy allows to identify that the main cause of deactivation is associated to the loss of TiO2 electrical conductivity, corresponding to a self-passivation mechanism. This is proposed to reflect the effect of OHions diffusing in the TiO2 structure in anodic conditions by the electric field. This fact proves that a modification takes place in the defective zone of the layer, blocking the ability to transfer electrical charge through the layer. According to this mechanism, a regeneration of the degradation process is demonstrated possible based on ultraviolet illumination, which contributes to change the occupancy of TiO2 electronic states and to recover the defective 3 zones conductivity. These findings confirm the connection between the structural properties of the ALD-deposited polycrystalline layer and the degradation mechanisms, and thus highlight main concerns towards fabricating long-lasting metal oxide protective layers for frontal illuminated photoelectrodes.Photoelectrochemical (PEC) water splitting was discovered by Fujishima and Honda in the late 70's, 7 but solar to hydrogen (STH) efficiencies have been far from industrial requirements for decades, although remarkable efforts have been put in understanding and enhancing photoactive metal oxide semiconductors and catalysts to perform the water splitting reaction. [8][9][10][11][12][13][14][15][16][17][18] With the significant increase in productivity and cost reduction of the photovoltaic industry, which has led to its large scale implementation, many authors have put their attention into implementing these semiconductor materials and fabrication meth...

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Carbon‐Based Photocathode Materials for Solar Hydrogen Production

2018

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Hydrogen is considered a promising environmentally friendly energy carrier for replacing traditional fossil fuels. In this context, photoelectrochemical cells effectively convert solar energy directly to H fuel by water photoelectrolysis, thereby monolitically combining the functions of both light harvesting and electrolysis. In such devices, photocathodes and photoanodes carry out the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. Here, the focus is on photocathodes for HER, traditionally based on metal oxides, III-V group and II-VI group semiconductors, silicon, and copper-based chalcogenides as photoactive material. Recently, carbon-based materials have emerged as reliable alternatives to the aforementioned materials. A perspective on carbon-based photocathodes is provided here, critically analyzing recent research progress and outlining the major guidelines for the development of efficient and stable photocathode architectures. In particular, the functional role of charge-selective and protective layers, which enhance both the efficiency and the durability of the photocathodes, is discussed. An in-depth evaluation of the state-of-the-art fabrication of photocathodes through scalable, high-troughput, cost-effective methods is presented. The major aspects on the development of light-trapping nanostructured architectures are also addressed. Finally, the key challenges on future research directions in terms of potential performance and manufacturability of photocathodes are analyzed.

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Protection of Si photocathode using TiO2 deposited by high power impulse magnetron sputtering for H2 evolution in alkaline media

Cited by 56 publications

References 44 publications

Durability Testing of Photoelectrochemical Hydrogen Production under Day/Night Light Cycled Conditions

Durability Testing of Photoelectrochemical Hydrogen Production under Day/Night Light Cycled Conditions

Insight into the Degradation Mechanisms of Atomic Layer Deposited TiO₂ as Photoanode Protective Layer

Carbon‐Based Photocathode Materials for Solar Hydrogen Production

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Protection of Si photocathode using TiO2 deposited by high power impulse magnetron sputtering for H2 evolution in alkaline media

Cited by 56 publications

References 44 publications

Durability Testing of Photoelectrochemical Hydrogen Production under Day/Night Light Cycled Conditions

Durability Testing of Photoelectrochemical Hydrogen Production under Day/Night Light Cycled Conditions

Insight into the Degradation Mechanisms of Atomic Layer Deposited TiO2 as Photoanode Protective Layer

Carbon‐Based Photocathode Materials for Solar Hydrogen Production

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Insight into the Degradation Mechanisms of Atomic Layer Deposited TiO₂ as Photoanode Protective Layer