| 1. |
- Zhang, Kaiyou, et al.
(författare)
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Synthesis and structure determination of potassium copper selenide nanowires and solid-state supercapacitor application
- 2014
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 268, s. 522-532
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Tidskriftsartikel (refereegranskat)abstract
- The new ternary alkali metal copper chalcogenide KCu4Se8 nanowires with average length of 30 mu m are synthesized using a modified composite-hydroxide mediated (M-CHM) approach. The prepared KCu4Se8 is characterized by XRD, EDS, FESEM and TEM analysis. The structure is determined by the newly developed Rotation Electron Diffraction technique. It is identified to be a body center tetragonal phase. The prepared KCu4Se8 is used to fabricate solid-state supercapacitors in which the thin film of the electrodes are made with pressure of 0 MPa, 5 MPa and 10 MPa, and their electrochemical properties are tested. It is found that 0 MPa supercapacitor displays best electrochemical performance and the specific capacitance of 25.3 F g(-1) is obtained at the scan rate of 5 mV s(-1). It also shows good long-term cycle property by recording 5000 cycles of galvanostatic charge/discharge operation. The specific capacitance can be enhanced to 93.7 F g(-1) at the scan rate of 5 mV s(-1) by coating 0.1 mg V2O5 nanowire on 0 MPa KCu4Se8 electrode.
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| 2. |
- Guo, Donglin, et al.
(författare)
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Highly restricted near-surface permafrost extent during the mid-Pliocene warm period
- 2023
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 120:36
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Tidskriftsartikel (refereegranskat)abstract
- Accurate understanding of permafrost dynamics is critical for evaluating and mitigating impacts that may arise as permafrost degrades in the future; however, existing projections have large uncertainties. Studies of how permafrost responded historically during Earth's past warm periods are helpful in exploring potential future permafrost behavior and to evaluate the uncertainty of future permafrost change projections. Here, we combine a surface frost index model with outputs from the second phase of the Pliocene Model Intercomparison Project to simulate the near-surface (similar to 3 to 4 m depth) permafrost state in the Northern Hemisphere during the mid-Pliocene warm period (mPWP, similar to 3.264 to 3.025 Ma). This period shares similarities with the projected future climate. Constrained by proxy-based surface air temperature records, our simulations demonstrate that near-surface permafrost was highly spatially restricted during the mPWP and was 93 +/- 3% smaller than the preindustrial extent. Near-surface permafrost was present only in the eastern Siberian uplands, Canadian high Arctic Archipelago, and northernmost Greenland. The simulations are similar to near-surface permafrost changes projected for the end of this century under the SSP5-8.5 scenario and provide a perspective on the potential permafrost behavior that may be expected in a warmer world.
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| 3. |
- Zheng, Siyu, et al.
(författare)
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Strong Coupling of Colloidal Quantum Dots via Self-Assemble Passivation for Efficient Infrared Solar Cells
- 2021
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Ingår i: Advanced Materials Interfaces. - : John Wiley & Sons. - 2196-7350. ; 8:13
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Tidskriftsartikel (refereegranskat)abstract
- The surface passivation of colloidal quantum dots (CQD) is critical for the electronic coupling of CQDs, which significantly affects the photovoltaic performance of CQD solar cells (CQDSCs). Herein, a self-assemble passivation (SAP) strategy of CQDs is introduced to improve CQD coupling. The PbI2 passivation layer prepared using the SAP method can largely improve surface defect passivation of CQDs, diminishing charge recombination induced by the sub-bandgap traps. Meanwhile, extensive theoretical simulations reveal that the self-assembled PbI2 passivation layer works as a "charger bridge" for charge transport between the adjacent CQDs, avoiding CQD fusion. The infrared CQDSCs are fabricated and the SAP-based CQDSC yields an efficiency of up to 12.3%, which is significantly improved compared with that of the conventional CQDSCs with iodide passivating CQD surface. The improved photovoltaic performance in the SAP-based CQDSCs is attributed to increased charge extraction, resulting from strong CQD coupling within the CQD solid films. This work provides a simple and facile way to improve the electronic coupling of CQDs for high-performance infrared CQDSCs.
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| 4. |
- Zhou, Shuai, et al.
(författare)
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The calculation of InGaN quantum dot formation mechanism on GaN pyramid
- 2015
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Ingår i: Superlattices and Microstructures. - : Elsevier. - 0749-6036 .- 1096-3677. ; 84, s. 72-79
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Tidskriftsartikel (refereegranskat)abstract
- An equilibrium approach is used to calculate the free energy and composition distribution of InGaN/GaN quantum dot located on the InGaN/GaN pyramid. The energy balance method is adopted to predict critical conditions for quantum dot formation. We find that the formation of QD depends strongly on the size of pyramid top surface. The results can fit our experiment qualitatively.
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