Nature and Role of Surface Junctions in BiOIO<sub>3</sub> Photocatalysts

Liberto, Giovanni Di; Tosoni, Sergio; Pacchioni, Gianfranco

doi:10.1002/adfm.202009472

Cited by 25 publications

(11 citation statements)

References 86 publications

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“…60 E form = 0.66 J m −2 indicates a high stability of the interface. 61 Furthermore, the formation of the interface from the separated WO 3 and BiVO 4 slabs implies an energy gain by 0.13 J m −2 , as evidenced by the calculated adhesion energy E ad , defined as the energy of the interface minus that of the separated slabs.…”

Section: Resultssupporting

confidence: 83%

WO₃/BiVO₄ Photoanodes: Facets Matching at the Heterojunction and BiVO₄ Layer Thickness Effects

Grigioni

Liberto

Dozzi

et al. 2021

ACS Appl. Energy Mater.

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Photoelectrochemical solar energy conversion offers a way to directly store light into energy-rich chemicals. Photoanodes based on the WO3/BiVO4 heterojunction are most effective mainly thanks to the efficient separation of photogenerated charges. The WO3/BiVO4 interfacial space region in the heterojunction is investigated here with the increasing thickness of the BiVO4 layer over a WO3 scaffold. On the basis of X-ray diffraction analysis results, density functional theory simulations show a BiVO4 growth over the WO3 layer along the BiVO4 {010} face, driven by the formation of a stable interface with new covalent bonds, with a favorable band alignment and band bending between the two oxides. This crystal facet phase matching allows a smooth transition between the electronic states of the two oxides and may be a key factor ensuring the high efficiency attained with this heterojunction. The photoelectrochemical activity of the WO3/BiVO4 photoanodes depends on both the irradiation wavelength and the thickness of the visible-light-absorbing BiVO4 layer, a 75 nm thick BiVO4 layer on WO3 being best performing.

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Section: Resultssupporting

confidence: 83%

WO₃/BiVO₄ Photoanodes: Facets Matching at the Heterojunction and BiVO₄ Layer Thickness Effects

Grigioni

Liberto

Dozzi

et al. 2021

ACS Appl. Energy Mater.

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“…In fact, calculations done at the PBE0 DD level with the CRYSTAL code show unambiguously that the most stable (010) and (100) surfaces of BiOIO 3 exhibit VBM and CBM positions which are reversed compared to experiment. [111] To reconcile theory with experiment, it is necessary to invoke the formation of a junction between a less stable (010) surface termination of BiOIO 3 with the most stable (100) one. When this is done new chemical bonds at the interface result in a thermodynamically stable system and a significant charge polarization at the interface.…”

Section: Type‐ii Heterojunctions: Joining Different Facets Of the Same Semiconductormentioning

confidence: 99%

Rational Design of Semiconductor Heterojunctions for Photocatalysis

Liberto

Cipriano

Tosoni

et al. 2021

Chemistry A European J

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Electronic structure calculations provide a useful complement to experimental characterization tools in the atomic-scale design of semiconductor heterojunctions for photocatalysis. The band alignment of the heterojunction is of fundamental importance to achieve an efficient charge carrier separation, so as to reduce electron/hole recombination and improve photoactivity. The accurate prediction of the offsets of valence and conduction bands in the constituent units is thus of key importance but poses several methodological and practical problems. In this Minireview we address some of these problems by considering selected examples of binary and ternary semiconductor heterojunctions and how these are determined at the level of density functional theory (DFT). The atomically precise description of the interface, the consequent charge polarization, the role of quantum confinement, the possibility to use facet engineering to determine a specific band alignment, are among the effects discussed, with particular attention to pros and cons of each one of these aspects. This analysis shows the increasingly important role of accurate electronic structure calculations to drive the design and the preparation of new interfaces with desired properties.

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“…60 Graphical visualizations have been made using OVITO. 61 The charge density difference was defined as 62,63 Δρ = ρ s1/s2 − (ρ s1 + ρ s2 ), where ρ s1 and ρ s2 are densities of independent surfaces and ρ s1/s2 is the electron density of the interface.…”

Section: ■ Introductionmentioning

confidence: 99%

Mind the Interface Gap: Exposing Hidden Interface Defects at the Epitaxial Heterostructure between CuO and Cu₂O

Živković

Mallia

et al. 2022

ACS Appl. Mater. Interfaces

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Well designed and optimized epitaxial heterostructures lie at the foundation of materials development for photovoltaic, photocatalytic, and photoelectrochemistry applications. Heterostructure materials offer tunable control over charge separation and transport at the same time preventing recombination of photogenerated excitations at the interface. Thus, it is of paramount importance that a detailed understanding is developed as the basis for further optimization strategies and design. Oxides of copper are nontoxic, low cost, abundant materials with a straightforward and stable manufacturing process. However, in individual applications, they suffer from inefficient charge transport of photogenerated carriers. Hence, in this work, we investigate the role of the interface between epitaxially aligned CuO and Cu 2 O to explore the potential benefits of such an architecture for more efficient electron and hole transfer. The CuO/Cu 2 O heterojunction nature, stability, bonding mechanism, interface dipole, electronic structure, and band bending were rationalized using hybrid density functional theory calculations. New electronic states are identified at the interface itself, which are originating neither from lattice mismatch nor strained Cu−O bonds. They form as a result of a change in coordination environment of CuO surface Cu 2+ cations and an electron transfer across the interface Cu 1+ −O bond. The first process creates occupied defect-like electronic states above the valence band, while the second leaves hole states below the conduction band. These are constitutional to the interface and are highly likely to contribute to recombination effects competing with the improved charged separation from the suitable band bending and alignment and thus would limit the expected output photocurrent and photovoltage. Finally, a favorable effect of interstitial oxygen defects has been shown to allow for band gap tunability at the interface but only to the point of the integral geometrical contact limit of the heterostructure itself.

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Nature and Role of Surface Junctions in BiOIO₃ Photocatalysts

Cited by 25 publications

References 86 publications

WO₃/BiVO₄ Photoanodes: Facets Matching at the Heterojunction and BiVO₄ Layer Thickness Effects

WO₃/BiVO₄ Photoanodes: Facets Matching at the Heterojunction and BiVO₄ Layer Thickness Effects

Rational Design of Semiconductor Heterojunctions for Photocatalysis

Mind the Interface Gap: Exposing Hidden Interface Defects at the Epitaxial Heterostructure between CuO and Cu₂O

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Nature and Role of Surface Junctions in BiOIO3 Photocatalysts

Cited by 25 publications

References 86 publications

WO3/BiVO4 Photoanodes: Facets Matching at the Heterojunction and BiVO4 Layer Thickness Effects

WO3/BiVO4 Photoanodes: Facets Matching at the Heterojunction and BiVO4 Layer Thickness Effects

Rational Design of Semiconductor Heterojunctions for Photocatalysis

Mind the Interface Gap: Exposing Hidden Interface Defects at the Epitaxial Heterostructure between CuO and Cu2O

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Nature and Role of Surface Junctions in BiOIO₃ Photocatalysts

WO₃/BiVO₄ Photoanodes: Facets Matching at the Heterojunction and BiVO₄ Layer Thickness Effects

WO₃/BiVO₄ Photoanodes: Facets Matching at the Heterojunction and BiVO₄ Layer Thickness Effects

Mind the Interface Gap: Exposing Hidden Interface Defects at the Epitaxial Heterostructure between CuO and Cu₂O