Local structure analysis and structure mining for design of photocatalytic metal oxychloride intergrowths

Chatterjee, Kaustav; Magnard, Nicolas; Mathiesen, Jette K.; Jensen, Kirsten M. Ø.; Skrabalak, Sara E.

doi:10.1039/d2ta05663a

Cited by 2 publications

(2 citation statements)

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“…However, in Bi 4 TaO 8 Cl− Bi 2 GdO 4 Cl intergrowth, distortion of [TaO 6 ] octahedra preserves the structure of [Bi 2 GdO 4 ]. 54 The distortion of [TaO 6 ] octahedra leads to greater mobility of photogenerated electron−hole pairs, increasing the probability of the charge carriers to reach active sites on the surface of the photocatalyst and enhancing photocatalytic performance.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…These distortions enable chemical changes under the reaction conditions for photocatalytic HER, with the point defects generated by distortions serving as the recombination sites of photogenerated charge carriers. However, in Bi 4 TaO 8 Cl–Bi 2 GdO 4 Cl intergrowth, distortion of [TaO 6 ] octahedra preserves the structure of [Bi 2 GdO 4 ] . The distortion of [TaO 6 ] octahedra leads to greater mobility of photogenerated electron–hole pairs, increasing the probability of the charge carriers to reach active sites on the surface of the photocatalyst and enhancing photocatalytic performance.…”

Section: Resultsmentioning

confidence: 99%

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Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi₄NbO₈Cl–Bi₂GdO₄Cl Intergrowths

Christudas Beena,

Magnard,

Puggioni

et al. 2024

Inorg. Chem.

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Mixed metal oxyhalides are an exciting class of photocatalysts, capable of the sustainable generation of fuels and remediation of pollutants with solar energy. Bismuth oxyhalides of the types Bi 4 MO 8 X (M = Nb and Ta; X = Cl and Br) and Bi 2 AO 4 X (A = most lanthanides; X = Cl, Br, and I) have an electronic structure that imparts photostability, as their valence band maxima (VBM) are composed of O 2p orbitals rather than X np orbitals that typify many other bismuth oxyhalides. Here, flux-based synthesis of intergrowth Bi 4 NbO 8 Cl−Bi 2 GdO 4 Cl is reported, testing the hypothesis that both intergrowth stoichiometry and M identity serve as levers toward tunable optoelectronic properties. X-ray scattering and atomically resolved electron microscopy verify intergrowth formation. Facile manipulation of the Bi 4 NbO 8 Cl-to-Bi 2 GdO 4 Cl ratio is achieved with the specific ratio influencing both the crystal and electronic structures of the intergrowths. This compositional flexibility and crystal structure engineering can be leveraged for photocatalytic applications, with comparisons to the previously reported Bi 4 TaO 8 Cl−Bi 2 GdO 4 Cl intergrowth revealing how subtle structural and compositional features can impact photocatalytic materials.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi₄NbO₈Cl–Bi₂GdO₄Cl Intergrowths

Christudas Beena,

Magnard,

Puggioni

et al. 2024

Inorg. Chem.

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Electronic and nanoscale structures of metal oxyhalide intergrowth photocatalysts

Chatterjee,

Stanley,

Dravid

et al. 2023

Applied Physics Letters

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Multimetal oxyhalide intergrowths show promise for photocatalytic water splitting. However, the relationships between intergrowth stoichiometry and their electronic and nanoscale structures are yet to be identified. This study investigates Bi4TaO8Cl–Bi2GdO4Cl intergrowths and demonstrates that stoichiometry controls the tilting of [TaO6] octahedra, influencing the bandgap of the photocatalyst and its valence and conduction band positions. To determine how the [TaO6] octahedral tilting in the intergrowths manifests as a function of intergrowth stoichiometry, we investigated changes in crystal symmetry by analyzing features arising at the higher order Laue zone (HOLZ) of convergent-beam electron diffraction patterns. Higher Ta content intergrowths displayed a more intense outer HOLZ ring compared to lower Ta content intergrowths, indicating transformation from P21cn (orthorhombic) to P4/mmm (tetragonal). This finding suggests that more distortion occurs along the ⟨001⟩ directions of the crystal than the ⟨100⟩ and ⟨010⟩ directions. This variation directly impacts the electronic structure, affecting both conduction and valence band energy levels. By combining ultraviolet photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy, and electron energy loss spectroscopy, the absolute band positions of the intergrowths were determined. Agreement between the bandgaps obtained via ensemble and nanoscale measurements indicates nanoscale homogeneity of the electronic structure. Overall, the integrated approach establishes that the bandgap energy increases with increasing Ta content, which is correlated with the crystal symmetry and [TaO6] octahedral tilting. Broadly, the modular nature of intergrowths provides building block layers to tune octahedral tilting within perovskite layers for manipulation of optoelectronic properties.

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Local structure analysis and structure mining for design of photocatalytic metal oxychloride intergrowths

Abstract: Local structures of synthesized, durable and high-activity Bi4TaO8Cl–Bi2GdO4Cl intergrowth photocatalysts are investigated by pair distribution function, structure mining and strain analysis and correlated to their optoelectronic properties.

Cited by 2 publications

References 55 publications

Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi₄NbO₈Cl–Bi₂GdO₄Cl Intergrowths

Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi₄NbO₈Cl–Bi₂GdO₄Cl Intergrowths

Electronic and nanoscale structures of metal oxyhalide intergrowth photocatalysts

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Local structure analysis and structure mining for design of photocatalytic metal oxychloride intergrowths

Abstract: Local structures of synthesized, durable and high-activity Bi4TaO8Cl–Bi2GdO4Cl intergrowth photocatalysts are investigated by pair distribution function, structure mining and strain analysis and correlated to their optoelectronic properties.

Cited by 2 publications

References 55 publications

Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi4NbO8Cl–Bi2GdO4Cl Intergrowths

Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi4NbO8Cl–Bi2GdO4Cl Intergrowths

Electronic and nanoscale structures of metal oxyhalide intergrowth photocatalysts

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Product

Resources

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Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi₄NbO₈Cl–Bi₂GdO₄Cl Intergrowths

Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi₄NbO₈Cl–Bi₂GdO₄Cl Intergrowths