An integrated n-Si/BiVO<sub>4</sub> photoelectrode with an interfacial bi-layer for unassisted solar water splitting

Wang, Shujie; Feng, Shijia; Liu, Bin; Gong, Zichen; Wang, Tuo; Gong, Jinlong

doi:10.1039/d2sc06651c

Cited by 12 publications

(7 citation statements)

References 77 publications

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“…BiVO 4 growth in the [001] direction is thus anticipated on YSZ(001). On top of this, since YSZ(001) grows epitaxially on Si(100), [29][30][31][32] ITO, [33,34] and mica, [35,36] the choice of YSZ(001) as the substrate makes it relevant as a possible epitaxial buffer layer in realizing a number of possible all-epitaxial photoelectrochemical (PEC) device configurations, ranging from monolithic m-BiVO 4 /YSZ/n-Si integrated PEC tandem devices, [37] to flexible PEC devices on mica. Figure 1a shows the typical X-ray diffraction pattern of the BiVO 4 films deposited on YSZ(001).…”

Section: Resultsmentioning

confidence: 99%

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Fernandez

Grave

Krol

et al. 2023

Advanced Energy Materials

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Transition metal oxide (TMO) photoabsorbers are expected to play an important role in the development of renewable solar‐to‐fuel devices. Modest efficiencies have been demonstrated with devices based on TMO photoabsorbers, and further progress will likely rely on material property control beyond conventional bulk chemistry or nanostructuring strategies. To this end, model TMO photoabsorbers such as single crystalline monoclinic bismuth vanadate (BiVO4) are beneficial to advance the understanding of structure‐functionality relationships with minimal convoluted effects inherent in polycrystalline systems. Here, the authors reveal for the first time the effects of strain modulation strategies on the optoelectronic properties of epitaxial BiVO4 films synthesized by alternate‐target layer‐by‐layer pulsed laser deposition. Through a combination of high‐resolution X‐ray diffraction methods and optical and photoluminescence spectroscopies, the correlation between anisotropic, uniaxial strain‐driven bandgap widening and deviatoric strains associated with volume‐preserving lattice distortions is established. Broad polaronic photoluminescence signals are detected in epitaxial BiVO4, and its redshift is attributed to the structural distortion in BiO8 dodecahedra. Overall, the relationship between the structural and optoelectronic properties revealed in this study suggests that strain modulation and engineering of local distortion in complex transition metal oxides may be exploited as a viable strategy for the development of efficient photoabsorbers.

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Section: Resultsmentioning

confidence: 99%

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Fernandez

Grave

Krol

et al. 2023

Advanced Energy Materials

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“…Interfacial quality between the protection layer and the substrate is important in determining the charge carrier transfer efficiency. , The built-in field created in the photoelectrode device upon solar light illumination can be studied via open-circuit potential ( V oc ) measurement, where the difference between V oc under illumination and V oc in the dark could be translated into the photovoltage ( V ph ; V ph = V oc,light – V oc,dark ). ,− As shown in Figure a, without Pt cocatalyst and in the dark conditions, V oc of STO/rGO/Si was positioned ∼0.11 V lower than that of STO/Si, indicating the difference in surface potential alignment at the front layers of photocathodes. Upon illumination, V oc of STO/Si slightly moved down to ∼0.34 V vs RHE, representing a small V ph of ∼0.15 V, whereas that of STO/rGO/Si increased to ∼0.58 V vs RHE, which translated to V ph of ∼0.28 V. The generated photovoltage is basically equal to quasi-Fermi level splitting in the photoelectrode under illumination, and it signifies how efficient the charge carrier could be separated in the bulk (see Figure S12 and the Supporting Information for the discussion) .…”

Section: Resultsmentioning

confidence: 99%

Robust SrTiO₃ Passivation of Silicon Photocathode by Reduced Graphene Oxide for Solar Water Splitting

Ho,

Smiljanić,

Jovanović

et al. 2023

ACS Appl. Mater. Interfaces

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Development of a robust photocathode using low-cost and high-performing materials, e.g., p-Si, to produce clean fuel hydrogen has remained challenging since the semiconductor substrate is easily susceptible to (photo)corrosion under photoelectrochemical (PEC) operational conditions. A protective layer over the substrate to simultaneously provide corrosion resistance and maintain efficient charge transfer across the device is therefore needed. To this end, in the present work, we utilized pulsed laser deposition (PLD) to prepare a high-quality SrTiO3 (STO) layer to passivate the p-Si substrate using a buffer layer of reduced graphene oxide (rGO). Specifically, a very thin (3.9 nm ∼10 unit cells) STO layer epitaxially overgrown on rGO-buffered Si showed the highest onset potential (0.326 V vs RHE) in comparison to the counterparts with thicker and/or nonepitaxial STO. The photovoltage, flat-band potential, and electrochemical impedance spectroscopy measurements revealed that the epitaxial photocathode was more beneficial for charge separation, charge transfer, and targeted redox reaction than the nonepitaxial one. The STO/rGO/Si with a smooth and highly epitaxial STO layer outperforming the directly contacted STO/Si with a textured and polycrystalline STO layer showed the importance of having a well-defined passivation layer. In addition, the numerous pinholes formed in the directly contacted STO/Si led to the rapid degradation of the photocathode during the PEC measurements. The stability tests demonstrated the soundness of the epitaxial STO layer in passivating Si against corrosion. This study provided a facile approach for preparing a robust protection layer over a photoelectrode substrate in realizing an efficient and, at the same time, durable PEC device.

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“…To increase system flexibility, wireless monolithic cells are desired by depositing BiVO 4 directly on Si, eliminating glass and wires. However, direct n-Si to BiVO 4 connections impede unbiased water splitting 45 (Figure 9a) due to an insulating SiO x layer formed during BiVO 4 fabrication, which obstructs carrier transport. Furthermore, interface defects between n-Si/ SiO x /BiVO 4 lead to significant recombination, and the small band offset at the n-Si/BiVO 4 interface limits photovoltage generation.…”

Section: Monolithic Tandem Cellsmentioning

confidence: 99%

“…(d) Schematic, and (e) stability test of the tandem water splitting cell consisting of the integrated photoanode and a dark Pt cathode without external bias. Reproduced with permission from ref . Copyright 2023, Royal Society of Chemistry.…”

Section: Strategies To Increase the Application Potential Of Silicon ...mentioning

confidence: 99%

Advancing Silicon-Based Photoelectrodes toward Practical Artificial Photosynthesis

Wang,

Liu,

Wang

et al. 2024

Acc. Mater. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Artificial photosynthesis is a sustainable technology to convert solar energy into storable chemicals or fuels, which potentially paves the way for coping with the greenhouse gas emission and growing energy demand. Semiconductor photoelectrodes are vital constituents in artificial photosynthesis systems. Among them, silicon (Si) is extensively employed due to its earth abundance, suitable band gap, and low cost. However, Si-based photoelectrodes suffer from insufficient photovoltage, serious interfacial charge recombination, sluggish reaction kinetics, and low stability in electrolyte.Numerous strategies have been proposed to address these challenges. Si-based photoelectrodes comprising buried junctions, passivation/protective layers, and electrocatalysts as the main components have thus been developed. Unfortunately, several issues persist: (1) the additional defect state at the newly formed interfaces;(2) the contradiction between adequate passivation/protection and sufficient charge transfer;(3) the parasitic light absorption of electrocatalyst; and (4) the lack of compatibility with different application scenarios. Therefore, it is paramount to meticulously balance the functionalities and potential detrimental impacts brought about by different components to govern the photoelectrode design. This Account describes recent advances in Si-based photoelectrode design toward high efficiency, excellent stability, and practical applications in artificial photosynthesis. The charge utilization efficiency is determined by charge generation, separation, and transport processes, which could be simultaneously improved by the careful designs of homo/heterojunctions, bifacial passivation, and illumination-reaction decoupling. The above methods have been proven to be efficient, as through them we have obtained benchmark Si-based photocathodes. Apart from efficiency, stability is another key factor. We explored the charge transport and deactivation mechanisms of the traditional metal oxide protective layers, varied the coverage and surface energy of organic protective layers to control the flux of photogenerated charge, and discussed the merits of metal protective layers in illumination-reaction decoupled photoelectrodes. Moreover, the versatility of our Si-based photoelectrodes in unbiased water splitting with separated and integrated configurations, as well as in CO 2 reduction with H-cell and flow cell, is proposed. Finally, the key challenges and future perspectives toward practical artificial synthesis are suggested. Our collective work outlines strategies for efficient and stable Si-based photoelectrodes. These general methods may be applicable to other semiconductor photoelectrodes for artificial synthesis.

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An integrated n-Si/BiVO₄ photoelectrode with an interfacial bi-layer for unassisted solar water splitting

Abstract: The integrated n-Si/BiVO4 is one of the most promising candidates for unbiased photoelectrochemical water splitting. However, the direct connection between n-Si and BiVO4 will not attain overall water splitting due...

Cited by 12 publications

References 77 publications

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Robust SrTiO₃ Passivation of Silicon Photocathode by Reduced Graphene Oxide for Solar Water Splitting

Advancing Silicon-Based Photoelectrodes toward Practical Artificial Photosynthesis

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An integrated n-Si/BiVO4 photoelectrode with an interfacial bi-layer for unassisted solar water splitting

Abstract: The integrated n-Si/BiVO4 is one of the most promising candidates for unbiased photoelectrochemical water splitting. However, the direct connection between n-Si and BiVO4 will not attain overall water splitting due...

Cited by 12 publications

References 77 publications

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO4 Films

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO4 Films

Robust SrTiO3 Passivation of Silicon Photocathode by Reduced Graphene Oxide for Solar Water Splitting

Advancing Silicon-Based Photoelectrodes toward Practical Artificial Photosynthesis

Contact Info

Product

Resources

About

An integrated n-Si/BiVO₄ photoelectrode with an interfacial bi-layer for unassisted solar water splitting

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Robust SrTiO₃ Passivation of Silicon Photocathode by Reduced Graphene Oxide for Solar Water Splitting