Synthesis and Structure of the Double-Layered Sillén–Aurivillius Perovskite Oxychloride La_2.1Bi_2.9Ti₂O₁₁Cl as a Potential Photocatalyst for Stable Visible Light Solar Water Splitting

Abstract

Exploring photocatalysts for solar water splitting is a relevant step toward sustainable hydrogen production. Silleń−Aurivillius-type compounds have proven to be a promising material class for photocatalytic and photoelectrochemical water splitting with the advantage of visible light activity coupled to enhanced stability because of their unique electronic structure. Especially, double-and multilayered Silleń−Aurivillius compoundswith A and B being cations and X a halogen anion, offer a great variety in material composition and properties. Yet, research in this field is limited to only a few compounds, all of them containing mainly Ta 5+ or Nb 5+ as cations. This work takes advantage of the outstanding properties of Ti 4+ demonstrated in the context of photocatalytic water splitting. A fully titanium-based oxychloride, La 2.1 Bi 2.9 Ti 2 O 11 Cl, with a double-layered Silleń− Aurivillius intergrowth structure is fabricated via a facile one-step solid-state synthesis. A detailed crystal structure analysis is performed via powder X-ray diffraction and correlated to density functional theory calculations, providing a detailed understanding of the site occupancies in the unit cell. The chemical composition and the morphology are studied using scanning and transmission electron microscopy together with energy-dispersive X-ray analysis. The capability of the compound to absorb visible light is demonstrated by UV−vis spectroscopy and analyzed by electronic structure calculations. The activity toward the hydrogen and the oxygen evolution reaction is evaluated by measuring anodic and cathodic photocurrent densities, oxygen evolution rates, and incident-current-to-photon efficiencies. Thanks to the incorporation of Ti 4+ , this Silleń−Aurivillius-type compound enables best-inclass photoelectrochemical water splitting performance at the oxygen evolution side under visible light irradiation. Thus, this work highlights the potential of Ti-containing Silleń−Aurivillius-type compounds as stable photocatalysts for visible light-driven solar water splitting.

Double-Layered Sillen–Aurivillius Perovskite Oxybromide Sr2Bi3Nb2O11Br as a Fatigue-Free Piezocatalyst with Ultrahigh Hydrogen Evolution Performance

“…O3 and O4 are situated at the interface of [BiSrO 2 ] + and the perovskite layers and near the halide layer, respectively. The presence of the Bi 2 O 2 layer and the distortion-induced structure of Sr 2 Bi 3 Nb 2 O 11 Br as revealed by the SHG studies is likely to confer inherent polarization properties, contributing to efficient and fatigue-resistant piezocatalytic activity. ,,− …”

Band engineering of layered oxyhalide photocatalysts for visible-light water splitting

“…Other cations, such as Pb 2+ , La 3+ , and Sr 2+ , can substitute these sites, though the occupation is partial in most cases. For Sillén–Aurivillius phases, such as La 2.1 Bi 2.9 Ti 2 O 11 Cl, 81 the alkali earth metal and lanthanide cations tend to prefer the M site on the perovskite layer side, probably due to the stereoactive LPEs of Bi 3+ favoring an asymmetric environment coordinated to opposite halide ligands to form MO 4 X 4 ( vs. MO 8 ). 31,45,68,81 Lone pair cations ( e.g.…”

“…For Sillén–Aurivillius phases, such as La 2.1 Bi 2.9 Ti 2 O 11 Cl, 81 the alkali earth metal and lanthanide cations tend to prefer the M site on the perovskite layer side, probably due to the stereoactive LPEs of Bi 3+ favoring an asymmetric environment coordinated to opposite halide ligands to form MO 4 X 4 ( vs. MO 8 ). 31,45,68,81 Lone pair cations ( e.g. , Bi 3+ and Pb 2+ ) in the fluorite layer determine the VBM position via lone pair interactions; in MBiO 2 X (M = Sr, Ba, Pb), and the VBM position can be tuned with M (Fig.…”

“…Increasing the perovskite layer n of Sillén–Aurivillius phases (M 4 A n −1 B n O 3 n +5 X) provides broad compositional and structural variations and changes optical and electrochemical properties. 36,38,67,81,116–122 For example, of the fourteen bilayer ( n = 2) M 4 AB 2 O 11 Cl (M = Bi, Pb, Ba, Sr; B = Ta, Nb, Ti), ten were discovered in 2019. 68…”

New pentlandite-like oxide semiconductors IrIn6XYO8 (X = Ga, In; Y = Ge, Sn, Ti) as potential candidates for photocatalytic water splitting under visible-light irradiation

“…As clean and renewable energy, hydrogen energy instead of fossil fuels is expected to be the most ideal and cost-effective route for solving environmental crises and energy shortage issues. [1][2][3] Since the seminal contributions by Fujishima and Honda, solar-driven water splitting has attracted significant attention as a promising strategy for producing hydrogen energy. 4 However, the obstacle limiting the development of this technology is the lack of highlyefficient and stable photocatalysts so far.…”