| 1. |
- Apostolopoulou-Kalkavoura, Varvara, 1988-, et al.
(författare)
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Humidity-Dependent Thermal Boundary Conductance Controls Heat Transport of Super-Insulating Nanofibrillar Foams
- 2021
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Ingår i: Matter. - : Elsevier BV. - 2590-2393 .- 2590-2385. ; 4:1, s. 276-289
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanomaterial (CNM)-based foams and aerogels with thermal conductivities substantially below the value for air attract significant interest as super-insulating materials in energy-efficient green buildings. However, the moisture dependence of the thermal conductivity of hygroscopic CNM-based materials is poorly understood, and the importance of phonon scattering in nanofibrillar foams remains unexplored. Here, we show that the thermal conductivity perpendicular to the aligned nanofibrils in super-insulating ice-templated nanocellulose foams is lower for thinner fibrils and depends strongly on relative humidity (RH), with the lowest thermal conductivity (14 mW m−1 K−1) attained at 35% RH. Molecular simulations show that the thermal boundary conductance is reduced by the moisture-uptake-controlled increase of the fibril-fibril separation distance and increased by the replacement of air with water in the foam walls. Controlling the heat transport of hygroscopic super-insulating nanofibrillar foams by moisture uptake and release is of potential interest in packaging and building applications.
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| 2. |
- Beal, Rachel E., et al.
(författare)
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Structural Origins of Light-Induced Phase Segregation in Organic-Inorganic Halide Perovskite Photovoltaic Materials
- 2020
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Ingår i: Matter. - : Elsevier BV. - 2590-2393 .- 2590-2385. ; 2:1, s. 207-219
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Tidskriftsartikel (refereegranskat)abstract
- Organic-inorganic metal-halide perovskite materials offer a promising route to reducing the dollars-per-watt cost of solar energy due to their good optoelectronic properties and facile, scalable processing. Compositional tuning allows for the preparation of absorbers with band gaps tailor-made for specific tandem and single-junction applications, but photoinduced phase segregation in mixed-halide materials leads to the formation of low-band-gap regions that reduce the voltage of devices. This work explores the structural origins of photoinduced phase segregation in FA(y)Cs(1-y)Pb(BrxI1-x)(3) perovskite alloys. We use synchrotron X- ray diffraction to map the solvus between the cubic and cubic-tetragonal mixed-phase region and time-dependent photoluminescence to assess stability under illumination. We show that the correlation between crystallographic phase and phase-segregation behavior is imperfect, so phase is not the sole determinant of optical stability. Instead, we consider several possible mechanisms that could underlie the dependence of optical stability on perovskite composition.
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| 3. |
- Bischak, Connor G., et al.
(författare)
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Liquid-like Interfaces Mediate Structural Phase Transitions in Lead Halide Perovskites
- 2020
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Ingår i: Matter. - : Elsevier BV. - 2590-2393 .- 2590-2385. ; 3:2, s. 534-545
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Tidskriftsartikel (refereegranskat)abstract
- Microscopic pathways of structural phase transitions inmetal halide perovskites are difficult to probe because they occur over disparate time and length scales and because electron-based microscopies typically used to directly probe nanoscale dynamics of phase transitions often damage metal halide perovskite materials. Using in situ nanoscale cathodoluminescence microscopy with low electron beam exposure, we visualize nucleation and growth in the thermally driven transition to the perovskite phase in hundreds of non-perovskite phase nanowires. In combination with molecular dynamics simulations, we reveal that the transformation does not follow a simple martensitic mechanism, but proceeds despite a substantial energy barrier via ion diffusion through a liquid-like interface between the two structures. While cations are disordered in this liquid-like region, the halide ions retain substantial spatial correlations. This detailed picture not only reveals how phase transitions between disparate structures can proceed, but also opens the possibility to control such processes.
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| 4. |
- Guimarães, Marcos, et al.
(författare)
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Disorder is not always bad for charge-to-spin conversion in WTe 2
- 2021
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Ingår i: Matter. - : Elsevier BV. - 2590-2393 .- 2590-2385. ; 4:5, s. 1440-1441
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Tidskriftsartikel (refereegranskat)abstract
- The Wang group at Stanford University demonstrates disordered WTe films for efficient charge-to-spin conversion phenomena. The deposition of these films by sputtering and the charge-to-spin conversion resilience against disorder make them attractive for applications in new magnetic memory devices.
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| 5. |
- Han, Ning, et al.
(författare)
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Lowering the kinetic barrier via enhancing electrophilicity of surface oxygen to boost acidic oxygen evolution reaction
- 2024
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Ingår i: Matter. - 2590-2393 .- 2590-2385. ; 7:3, s. 1330-1343
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Tidskriftsartikel (refereegranskat)abstract
- The acidic oxygen evolution reaction (OER) is essential for many renewable energy conversion and storage technologies. However, the high energy required to break the strong covalent O-H bond of H2O in acidic media results in sluggish OER kinetics. Here, we report the critical role of iron in a new family of iron-containing yttrium ruthenate (Y2-xFexRu2O7-δ) electrocatalysts in highly increasing the electrophilicity of surface oxygen, leading to a significant reduction of the kinetics barrier by 33%, thus an exceptional OER mass activity of 1,021 A· up to 12.4 and 7.7 times that of Y2Ru2O7-δ and RuO2, respectively. Introducing iron reduces the Mulliken atomic charge on the O sites in the generated Ru-O-Fe structure, thereby facilitating the acid-base nucleophilic assault from H2O and reducing the free energy on the rate-determining step of OER. This work provides an effective strategy to reduce the kinetics barrier to achieve highly efficient and economic OER in acidic conditions.
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| 6. |
- Jin, Bao, et al.
(författare)
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Phase transition structural superlubricity
- 2024
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Ingår i: Matter. - : Cell Press. - 2590-2393 .- 2590-2385.
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Tidskriftsartikel (refereegranskat)abstract
- Structural superlubricity refers to a state with almost vanishing friction and wear between crystalline surfaces in incommensurate configurations. However, thus far, this phenomenon has been observed only at solid-solid interfaces. Here, we constructed an in situ heterojunction between a crystalline boundary tribofilm and a pressure-induced solid-phase 1–dodecanol molecular layer, achieving structural superlubricity in a liquid-solid interface. This novel superlubricity state, termed phase transition structural superlubricity (PTSS), is induced by incommensurate slip at the in situ heterojunction. Atomic force microscopy experiments and molecular dynamics simulations demonstrated that the friction of in situ heterojunction exhibits a periodicity of 180°. Notably, the PTSS arises when the molecular axis of 1–dodecanol is oriented 90° to the direction of friction. These findings provide a novel design strategy for structural superlubricity and bridge the gap between liquid and solid superlubricity, shedding substantial light upon achieving structural superlubricity across a broad range of environments.
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| 7. |
- Li, Youbing, et al.
(författare)
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A-site alloying-guided universal design of noble metal-based MAX phases
- 2024
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Ingår i: Matter. - : Cell Press. - 2590-2393 .- 2590-2385. ; 7:2, s. 523-538
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Tidskriftsartikel (refereegranskat)abstract
- Mn+1AXn (MAX) phases have attracted significant attention due to their structural diversity and potential applications. Designing MAX phases with single-atom-thick A layers featuring 4d/5d-orbital electronic elements is interesting work. Here, we present a comprehensive report on noble metal-based M2(A1-xA′x)C (M = V, Ti, Nb; A = Al, Sn, In, Ga, Ge; A′ = Ru, Rh, Pd, Ir, Pt, Au and combinations thereof; 0 < x ≤ 0.4) phases featuring A sublayers of 4d/5d-orbital electronic elements through an A-site alloying strategy. The chemical composition of MAX phases can be adjusted by selecting different M- and A-site elements, with morphology tailored by distinct C sources. Furthermore, the V2(Sn0.8Pt0.2)C (15.7 wt % Pt) catalyst showed better performance for hydrogen evolution reaction compared to the commercial Pt/C (20 wt % Pt) electrode. This study highlights the prospects of A-site alloying for the design of novel MAX phases with unique properties and promising applications in electrocatalysis and beyond.
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| 8. |
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| 9. |
- Liu, Tianjun, et al.
(författare)
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Large-scale perovskite light-emitting diodes enabled by quantum-wire arrays: One step closer to commercialization
- 2022
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Ingår i: Matter. - : ELSEVIER. - 2590-2393 .- 2590-2385. ; 5:8, s. 2428-2430
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Halide perovskite light-emitting diodes (PeLEDs) are enticing candidates for displays and lighting. However, it remains a challenge for devices to upscale to large-area or non-planar structures with high uniformity. Recently, in Nature Photonics, Fan and co-workers developed perovskite quantum-wire arrays templated by porous alumina membranes to achieve highly uniform performance LEDs based on wafer-scale substrates and three-dimensional spherical structures.
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| 10. |
- Malina, Tomas, et al.
(författare)
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Tuning the transformation and cellular signaling of 2D titanium carbide MXenes using a natural antioxidant
- 2024
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Ingår i: Matter. - : CELL PRESS. - 2590-2393 .- 2590-2385. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- 2D titanium carbide (Ti3C2) MXenes have emerged as promising candidates for biomedical applications. However, the biological properties of these materials are poorly understood. Moreover, MXenes are prone to oxidation under ambient conditions. Here, we show that glutathione (GSH), a natural antioxidant present in millimolar concentrations in the cytosol of most cells, protects MXenes from oxidation in aqueous suspensions while preserving the biocompatibility of the material. Reactive molecular dynamics (RMD) simulations confirm that GSH protects MXenes. Moreover, we provide evidence of the intracellular biotransformation of Ti3C2 MXenes to the rutile form of TiO2, and we show that GSH tunes the transformation process, resulting in the secretion of pro -inflammatory interleukin (IL) -1b through a non -canonical, elastase-dependent pathway. These results are important because they shed new light on the biotransformation of Ti3C2 MXenes and its ramifications for cellular signaling.
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