First-principles study on the electronic properties of GeC/BSe van der Waals heterostructure: A direct Z-scheme photocatalyst for overall water splitting

Understanding Electronic Properties and Tunable Schottky Barriers in a Graphene/Boron Selenide van der Waals Heterostructure

“…After the geometric optimization, the interlayer spacing ( d ) between the graphene and the topmost BSe layer is 3.46 Å. Such an interlayer spacing is in line with that observed in other typical van der Waals (vdW) heterostructures. , Furthermore, to check the stability of the graphene/BSe heterostructure, we calculate the binding energy as follows E b = E H − ( E G + E B S e ) A where the total energies of the graphene/BSe heterostructure, isolated graphene, and BSe monolayers are represented by E H , E G , and E BSe , respectively. A stands for the surface area of the considered supercell.…”

Novel Z-Scheme BiOM1–xIx (M = Cl, Br)/β-Bi2O3-(001) and BiOI/β-Bi2O3-(001) Heterojunction Photocatalysts with O Vacancies: A Study on the Hybrid Density Functional Approach

“…For the band alignment, the migration path of the photoexcited electrons and holes is more likely to occur along the path-1 than along the path-2 in Figure b. The photoexcited electrons in the CB of β-Bi 2 O 3 could quickly transfer toward the VB of BiOI and recombine with the photogenerated holes in the VB of BiOI because of the driving forces from the built-in electric field and Coulomb attraction between holes and electrons. − In conjunction with the smaller energy gap between the CBM of β-Bi 2 O 3 and the VBM of BiOI, the interlayer recombination probability of the photogenerated electrons and holes should be much larger than the intralayer recombination probability. The photogenerated electrons with higher reduction capacity in the CB of BiOI could be retained or have a longer lifetime, and the electron migration from the CB of BiOI to the CB of β-Bi 2 O 3 is suppressed because of the dragging forces from the built-in electric field, the extra potential barrier induced by band bending, and Coulomb repulsion between the electrons in the CB of BiOI and the electrons in the CB of β-Bi 2 O 3.…”

“…The photogenerated electrons with higher reduction capacity in the CB of BiOI could be retained or have a longer lifetime, and the electron migration from the CB of BiOI to the CB of β-Bi 2 O 3 is suppressed because of the dragging forces from the built-in electric field, the extra potential barrier induced by band bending, and Coulomb repulsion between the electrons in the CB of BiOI and the electrons in the CB of β-Bi 2 O 3. − Similarly, the photogenerated holes with higher oxidation capacity in the VB of β-Bi 2 O 3 also should have a longer lifetime in the heterojunction. − Therefore, the electrons and holes in the BiOI/β-Bi 2 O 3 can be excited easily. Remarkably, they can be separated and migrate highly effectively in space.…”

“…Then, a larger number of electron–hole pairs are generated. Because of the driving forces from the built-in electric field and Coulomb attraction as well as the smaller energy gap between the CBM of β-Bi 2 O 3 and the VBM of BiOM (28/32) I (4/32) (M = Cl, Br), the photoexcited electrons in the CB of β-Bi 2 O 3 could rapidly transfer toward the VB of BiOM (28/32) I (4/32) (M = Cl, Br) and recombine with the photogenerated holes in the VB of BiOM (28/32) I (4/32) (M = Cl, Br). − Nevertheless, the photogenerated electrons with higher reduction capacity in the CB of the BiOM (28/32) I (4/32) (M = Cl, Br) should be retained because of the dragging forces from the built-in electric field, the extra potential barrier induced from band bending, and Coulomb repulsion. − The photogenerated holes with higher oxidation capacity in the VB of β-Bi 2 O 3 also should have a longer lifetime. − The charge migration path-1 is more favorable than the path-2 in Figure . Notably, the CBM level of the BiOM (1– x ) I x (M = Cl, Br) in the heterostructures increases; furthermore, the reduction power of the electrons in the CB of the BiOM (1– x ) I x is enhanced with increasing I doping concentration.…”

“…At the same time, in Figure a, it is seen that the induced impurity level makes the optical absorption of the heterostructure intensify enormously in the visible region. Furthermore, the electrons and holes in the heterojunction BiOCl (28/32) I (4/32) (V O )/β-Bi 2 O 3 can be generated and separated more effectively. − Moreover, the electrons that gather in the CB of BiOCl (28/32) I (4/32) (V O ) have a higher reduction ability in contrast to that without the O vacancy. The projected band structure and band alignment for the heterojunction BiOBr (28/32) I (4/32) (V O )/β-Bi 2 O 3 are also displayed in Figure .…”