| 1. |
- Lin, Ci, et al.
(författare)
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Improving photocatalytic hydrogen generation of g-C3N4 via efficient charge separation imposed by Bi2O2Se nanosheets
- 2024
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Ingår i: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 218
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Tidskriftsartikel (refereegranskat)abstract
- Enabling highly efficient photocatalytic hydrogen production from solar-driven water splitting is of immense potential and environmental significance. However, the crucial issue of the low utilization efficiency of photogenerated charges in most photocatalysts, such as polymeric graphitic carbon nitride, g-C3N4 (CN), hampers the overall photocatalytic activity and hinders practical applications. To surmount this parasitic phenomenon, we develop a heterojunction-based strategy that improves the charge separation efficiency in CN. The heterostructure is constructed between thermally exfoliated CN and liquid phase exfoliated Bi2O2Se (BOS) via a solution-phase, electrostatically driven self-assembly process. The properly aligned band positions between the two components create a built-in electric field, which endows the composite with an enhanced charge separation efficiency. The optimized Pt-deposited heterostructure photocatalyst exhibits a hydrogen production rate of 6481 μmol h−1 g−1, and an apparent quantum efficiency of 11.65% at 420 nm, compared to those of Pt-deposited ECN (4595 μmol h−1 g−1, 6.64 %). We validate the efficient charge separation effect and the prolonged lifetime of photogenerated carriers in the heterostructure using a series of comprehensive characterizations across multiple timescales, thus, elucidating the origin of the observed photocatalytic activity. This demonstration offers valuable insights into improving the utilization efficiency of photogenerated charges for photocatalysis by heterostructure engineering with materials of distinct electronic configurations.
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| 2. |
- Pournaghavi, Nezhat, et al.
(författare)
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Chiral edge transport along domain walls in magnetic topological insulator nanoribbons
- 2024
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 36:40
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Tidskriftsartikel (refereegranskat)abstract
- Quantum anomalous Hall insulators are topologically characterized by non-zero integer Chern numbers, the sign of which depends on the direction of the exchange field that breaks time-reversal symmetry. This feature allows the manipulation of the conducting chiral edge states present at the interface of two magnetic domains with opposite magnetization and opposite Chern numbers. Motivated by this broad understanding, the present study investigates the quantum transport properties of a magnetized B i 2 S e 3 topological insulator nanoribbon with a domain wall (DW) oriented either parallel or perpendicular to the transport direction. Employing an atomistic tight-binding model and a non-equilibrium Green’s function formalism, we calculate the quantum conductance and explore the nature of the edge states. We elucidate the conditions leading to exact conductance quantization and identify the origin of deviations from this behavior. Our analysis shows that although the conductance is quantized in the presence of the horizontal DW, the quantization is absent in the perpendicular DW case. Furthermore, the investigation of the spin character of the edge modes confirms that the conductance in the horizontal DW configuration is spin polarized. This finding underscores the potential of our system as a simple three dimensional spin-filter device.
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