Surface Analysis of Perovskite Oxynitride Thin Films as Photoelectrodes for Solar Water Splitting (original) (raw)
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Reactive Inorganic Vapor Deposition of Perovskite Oxynitride Films for Solar Energy Conversion
Research, 2019
The synthesis of perovskite oxynitrides, which are promising photoanode candidates for solar energy conversion, is normally accomplished by high-temperature ammonolysis of oxides and carbonate precursors, thus making the deposition of their planar films onto conductive substrates challenging. Here, we proposed a facile strategy to prepare a series of perovskite oxynitride films. Taking SrTaO 2 N as a prototype, we prepared SrTaO 2 N films on Ta foils under NH 3 flow by utilizing the vaporized SrCl 2 /SrCO 3 eutectic salt. The SrTaO 2 N films exhibit solar water-splitting photocurrents of 3.0 mA cm -2 at 1.23 V vs. RHE (reversible hydrogen electrode), which increases by 270% compared to the highest photocurrent (1.1 mA cm -2 at 1.23 V vs. RHE) of SrTaO 2 N reported in the literature. This strategy may also be applied to directly prepare a series of perovskite oxynitride films on conductive substrates such as ATaO 2 N ( A = Ca , Ba ) and ANbO 2 N ( A = Sr , Ba ).
The Journal of Physical Chemistry C, 2009
Thin films of the lanthanum titanium oxynitride perovskite (LaTiO x N y ) synthesized by reactive radio-frequency sputtering on conductive Nb-doped strontium titanate (Nb:SrTiO 3 ) substrates are evaluated as photoelectrodes for water splitting reaction under visible light. The films are characterized by X-ray diffraction analysis, energy-dispersive spectroscopy, scanning electron and atomic force microscopy, and ultraviolet-visible spectroscopy. Thin films with polycrystalline, oriented, or epitaxial structures are obtained depending on the substrate temperature and plasma composition. The band-gap energies of the films thus prepared are in the range 2.05-2.35 eV. Photoelectrochemical measurements reveal that the photoactivity of these films increases with the quality of film crystallization. The flat-band position of LaTiO x N y is found to change with pH of the reactant solution. Surface modification with colloidal IrO 2 is also demonstrated to result in a marked increase in photoactivity, with the modified epitaxial LaTiO x N y film exhibiting a photocurrent density of ca. 70 µA cm -2 at +1.0 V vs. Ag/AgCl at pH 4.5 in aqueous Na 2 SO 4 solution under irradiation at visible wavelengths (λ > 420 nm).
ACS Applied Energy Materials, 2019
The solar water splitting process assisted by semiconductor photocatalysts attracts growing research interests worldwide for the production of hydrogen as a clean and sustainable energy carrier. Due to their optical and electrical properties several oxynitride materials show great promise for the fabrication of efficient photocatalysts for solar water splitting. This study reports a comparative investigation of particle-and thin films-based photocatalysts using three different oxynitride materials. The absolute comparison of the photoelectrochemical activities favors the particle-based electrodes due to the better absorption properties and larger electrochemical surface area. However, thin films surpass the particlebased photoelectrodes due to their more suitable morphological features that improve the separation and mobility of the photo-generated charge carriers. Our analysis identifies what specific insights into the properties of materials can be achieved with the two complementary approaches.
Energy and Environmental Science, 2018
PAPER Félix Urbain et al. Multijunction Si photocathodes with tunable photovoltages from 2.0 V to 2.8 V for light induced water splitting #These authors contributed equally. Broader Context Clean energy conversion is crucial to sustain the rapid development of human society and mitigate the greenhouse effect and environmental pollution from fossil fuel. Practical utilization of clean energies requires the energy conversions involving different process such as photovoltaics (PV, from solar energy to electrical energy), electrocatalysis (EC, from electrical energy to chemical energy), photocatalysis (PC, from solar energy to chemical energy). A key issue to realize high-efficiency conversion process is to search stable, low-cost and environment-friendly functional materials. Due to the extreme structural and compositional flexibilities, oxide perovskites and their derivates are attractive candidates for the diverse applications aforementioned. This paper reviews the structural and compositional flexibility oxide perovskites and their derivatives and the progress of their applications in clean energy conversion. It attempts to describe how the properties of oxide perovskites and their derivates are tuned for specific applications. Abstract Searching for novel functional materials represents an important direction in the research and development of renewable energy. Due to the unique structural and compositional flexibility and high material stability, oxide perovskites and their derivatives have recently been extensively explored as a class of versatile materials for applications in electrocatalysis (EC), photocatalysis (PC) and photovoltaics (PV), showing great promises in catalytic activity and device stability. In this review, we firstly discuss the extreme flexibilities of oxide perovskites in terms of their structures and compositions, which lead to a treasure trove of materials for diverse applications. Secondly, the current status of their applications and challenges in EC, PC and PV are reviewed. We attempt to build the connections between the structural and compositional flexibility and the tunable materials properties desirable for various applications.
ACS nano, 2018
Nonmetallic materials with localized surface plasmon resonance (LSPR) have a great potential for solar energy harvesting applications. Exploring nonmetallic plasmonic materials is desirable yet challenging. Herein, an efficient nonmetallic plasmonic perovskite photoelectrode, namely, SrTiO, with a periodically ordered nanoporous structure showing an intense LSPR in the visible light region is reported. The crystalline-core@amorphous-shell structure of the SrTiO photoelectrode enables a strong LSPR due to the high charge carrier density induced by oxygen vacancies in the amorphous shell. The reversible tunability in LSPR of the SrTiO photoelectrode was observed by oxidation/reduction treatment and incident angle adjusting. Such a nonmetallic plasmonic SrTiO photoelectrode displays a dramatic plasmon-enhanced photoelectrochemical water splitting performance with a photocurrent density of 170.0 μA cm under visible light illumination and a maximum incident photon-to-current-conversion e...
Electronic Structure of Tantalum Oxynitride Perovskite Photocatalysts
Chemistry of Materials, 2013
The tantalum oxynitride perovskites ATaO 2 N (A = Ca, Sr, and Ba) and PrTaON 2 are promising candidates for the photocatalytic splitting of water under illumination with visible light. A combination of X-ray photoemission spectroscopy (XPS), Kelvin probe force microscopy (KPFM), UV−vis spectroscopy, and depth-resolved cathodoluminescence spectroscopy (DRCLS) has been used to determine the absolute conduction and valence band energy levels of these four compounds. All have conduction band edges that lie above the reduction potential for water and therefore are suitable for the photocatalytic production of hydrogen, whereas the valence band edges lie near the oxidation potential of water. The position of the conduction band edge is closely linked to the Ta−O/N−Ta bond angles and hence tilting of the octahedra, whereas the position of the valence band edge is more sensitive to the oxygen-to-nitrogen ratio.
Energy and Environmental Science, 2019
Broader Context Clean energy conversion is crucial to sustain the rapid development of human society and mitigate the greenhouse effect and environmental pollution from fossil fuel. Practical utilization of clean energies requires the energy conversions involving different process such as photovoltaics (PV, from solar energy to electrical energy), electrocatalysis (EC, from electrical energy to chemical energy), photocatalysis (PC, from solar energy to chemical energy). A key issue to realize high-efficiency conversion process is to search stable, low-cost and environment-friendly functional materials. Due to the extreme structural and compositional flexibilities, oxide perovskites and their derivates are attractive candidates for the diverse applications aforementioned. This paper reviews the structural and compositional flexibility oxide perovskites and their derivatives and the progress of their applications in clean energy conversion. It attempts to describe how the properties of oxide perovskites and their derivates are tuned for specific applications.