| 1. |
- Poliakov, Aleksandr, 1990, et al.
(författare)
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Top-down nanostructured multilayer MoS2 with atomically sharp edges for electrochemical hydrogen evolution reaction
- 2024
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Ingår i: Materials Today Nano. - 2588-8420. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- Cost-efficient and readily scalable platinum-free electrocatalysts are crucial for a smooth transition to future renewable energy systems. Top-down activation of MoS2 promises the production of sustainable hydrogen evolution electrocatalysts from the Earth-abundant molybdenite ore. Here, the deterministic nanopatterning of multilayer MoS2 with numerous zigzag edges is explored as a pathway to enhance hydrogen evolution reaction (HER). Nanopatterned single-nanosheet MoS2 electrodes are assessed by two highly localized electrochemical techniques: selected area voltammetry (with lithography-defined regions of electrode-electrolyte contact) and Scanning ElectroChemical Microscopy (SECM). The nanopatterning effect is the most pronounced after prolonged electrochemical cycling in an acidic electrolyte. The electrocatalytic hydrogen evolution activity of edge-enriched electrodes is dramatically enhanced: the maximum electrochemical current density (j) achieved at -510 mV vs. reversible hydrogen electrode (mV) is increased by two orders of magnitude, reaching >300 mA⋅cm−2. Both the and overpotentials are significantly reduced as well. Meanwhile, pristine MoS2 shows just ≈6 times j increase (≈30 mA⋅cm−2) after the very same cycling. The increased electrocatalytic activity comes with electrode morphology degradation, evidenced by ex-situ scanning electron microscopy. SECM directly visualizes stronger HER activity in the regions with densely located zigzag edges. Intense white light illumination significantly boosts HER on MoS2 electrodes due to the photo-enhanced MoS2 conductivity. These results improve the understanding and reveal the limitations of MoS2-based electrocatalytic water splitting.
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| 2. |
- Zhao, Y., et al.
(författare)
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Bismuth nanoplatelets : universal synthetic strategy and emerging application for PEC-type photodetectors
- 2023
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Ingår i: MATERIALS TODAY NANO. - : Elsevier BV. - 2588-8420. ; 23
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Tidskriftsartikel (refereegranskat)abstract
- Bi nanoplatelets (NPLs) with a narrow size distribution and high yield have been successfully fabricated by a novel two-step sonication-assisted solvothermal method. Applied as photo-electrochemical (PEC)-type photodetectors (PDs), it is shown that the Bi NPLs exhibit a pronounced photo-response ranging from the ultraviolet to the visible regions. The photo-response performance of Bi NPLs-based PDs was adjusted by external conditions and interpreted by density functional theory calculations in terms of the formation of the respective Bi-based compounds. The PEC results demonstrate that the optimal photocurrent density (P-ph) and photoresponsivity (R-ph) can reach 12.27 mu A/cm(2) and 3016 mu A/W in alkaline electrolytes, respectively. Besides, the Bi NPLs-based PDs exhibit superb long-term cycling stability (similar to 97.86% remained after 1000 cycles). We conclude that Bi NPLs demonstrate great promise as an emerging building block for the design of high-performance PEC-type PDs as well as other novel optoelectronic devices, holding the potential for breakthrough developments in these fields.
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| 3. |
- Östmans, Rebecca, et al.
(författare)
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Solidified water at room temperature hosting tailored fluidic channels by using highly anisotropic cellulose nanofibrils
- 2024
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Ingår i: Materials Today Nano. - : Elsevier BV. - 2588-8420. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- Highly anisotropic cellulose nanofibrils can solidify liquid water, creating self-supporting structures by incorporating a tiny number of fibrils. These fibrillar hydrogels can contain as much as 99.99 wt% water. The structure and mechanical properties of fibrillar networks have so far not been completely understood, nor how they solidify the bulk water at such low particle concentrations. In this work, the mechanical properties of cellulose fibrillar hydrogels in the dilute regime from a wt% perspective have been studied, and an elastoplastic model describing the network structure and its mechanics is presented. A significant insight from this work is that the ability of the fibrils to solidify water is very dependent on particle stiffness and the number of contact points it can form in the network structure. The comparison between the experimental results and the theoretical model shows that the fibrillar networks in the dilute regime form via a non-stochastic process since the fibrils have the time and freedom to find contact points during network formation by translational and rotational diffusion. The formed, dilute fibrillar network deforms by sliding fibril contacts upon straining the network beyond its elastic limit. Our results also show that before macroscopic failure, the fibril contacts are restored once the load is released. The exceptional properties of this solidified water are exploited to host fluidic channels, allowing directed fluid transportation in water. Finally, the microfluidic channels formed in the hydrogels are tailored by the layer-by-layer technique to be interactive against external stimuli, a characteristic envisioned to be useful in biomedical applications.
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