Boosting the performance of WO3/n-Si heterostructures for photoelectrochemical water splitting: from the role of Si to interface engineering

Yihui Zhao, Geert Brocks, Han Genuit, Reinoud Lavrijsen, Marcel A. Verheijen, Anja Bieberle-Hütter (Corresponding author)

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Uittreksel

Metal oxide/Si heterostructures make up an exciting design route to high-performance electrodes for photoelectrochemical (PEC) water splitting. By monochromatic light sources, contributions of the individual layers in WO3/n-Si heterostructures are untangled. It shows that band bending near the WO3/n-Si interface is instrumental in charge separation and transport, and in generating a photovoltage that drives the PEC process. A thin metal layer inserted at the WO3/n-Si interface helps in establishing the relation among the band bending depth, the photovoltage, and the PEC activity. This discovery breaks with the dominant Z-scheme design idea, which focuses on increasing the conductivity of an interface layer to facilitate charge transport, but ignores the potential profile around the interface. Based on the analysis, a high-work-function metal is predicted to provide the best interface layer in WO3/n-Si heterojunctions. Indeed, the fabricated WO3/Pt/n-Si photoelectrodes exhibit a 2 times higher photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and a 10 times enhancement at 1.6 V versus RHE compared to WO3/n-Si. Here, it is essential that the native SiO2 layer at the interface between Si and the metal is kept in order to prevent Fermi level pinning in the Schottky contact between the Si and the metal.

TaalEngels
Artikelnummer1900940
Aantal pagina's11
TijdschriftAdvanced Energy Materials
Volume9
Nummer van het tijdschrift26
DOI's
StatusGepubliceerd - 12 jul 2019

Vingerafdruk

Heterojunctions
Metals
Water
Electrodes
Hydrogen
Monochromators
Fermi level
Photocurrents
Oxides
Charge transfer

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    Citeer dit

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    title = "Boosting the performance of WO3/n-Si heterostructures for photoelectrochemical water splitting: from the role of Si to interface engineering",
    abstract = "Metal oxide/Si heterostructures make up an exciting design route to high-performance electrodes for photoelectrochemical (PEC) water splitting. By monochromatic light sources, contributions of the individual layers in WO3/n-Si heterostructures are untangled. It shows that band bending near the WO3/n-Si interface is instrumental in charge separation and transport, and in generating a photovoltage that drives the PEC process. A thin metal layer inserted at the WO3/n-Si interface helps in establishing the relation among the band bending depth, the photovoltage, and the PEC activity. This discovery breaks with the dominant Z-scheme design idea, which focuses on increasing the conductivity of an interface layer to facilitate charge transport, but ignores the potential profile around the interface. Based on the analysis, a high-work-function metal is predicted to provide the best interface layer in WO3/n-Si heterojunctions. Indeed, the fabricated WO3/Pt/n-Si photoelectrodes exhibit a 2 times higher photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and a 10 times enhancement at 1.6 V versus RHE compared to WO3/n-Si. Here, it is essential that the native SiO2 layer at the interface between Si and the metal is kept in order to prevent Fermi level pinning in the Schottky contact between the Si and the metal.",
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    Boosting the performance of WO3/n-Si heterostructures for photoelectrochemical water splitting : from the role of Si to interface engineering. / Zhao, Yihui; Brocks, Geert; Genuit, Han; Lavrijsen, Reinoud; Verheijen, Marcel A.; Bieberle-Hütter, Anja (Corresponding author).

    In: Advanced Energy Materials, Vol. 9, Nr. 26, 1900940, 12.07.2019.

    Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

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    T2 - Advanced Energy Materials

    AU - Zhao,Yihui

    AU - Brocks,Geert

    AU - Genuit,Han

    AU - Lavrijsen,Reinoud

    AU - Verheijen,Marcel A.

    AU - Bieberle-Hütter,Anja

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    AB - Metal oxide/Si heterostructures make up an exciting design route to high-performance electrodes for photoelectrochemical (PEC) water splitting. By monochromatic light sources, contributions of the individual layers in WO3/n-Si heterostructures are untangled. It shows that band bending near the WO3/n-Si interface is instrumental in charge separation and transport, and in generating a photovoltage that drives the PEC process. A thin metal layer inserted at the WO3/n-Si interface helps in establishing the relation among the band bending depth, the photovoltage, and the PEC activity. This discovery breaks with the dominant Z-scheme design idea, which focuses on increasing the conductivity of an interface layer to facilitate charge transport, but ignores the potential profile around the interface. Based on the analysis, a high-work-function metal is predicted to provide the best interface layer in WO3/n-Si heterojunctions. Indeed, the fabricated WO3/Pt/n-Si photoelectrodes exhibit a 2 times higher photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and a 10 times enhancement at 1.6 V versus RHE compared to WO3/n-Si. Here, it is essential that the native SiO2 layer at the interface between Si and the metal is kept in order to prevent Fermi level pinning in the Schottky contact between the Si and the metal.

    KW - PEC water splitting

    KW - photovoltages

    KW - Si

    KW - WO/n-Si

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