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At least 631 records · Page 35

Improved cycle stability and high-rate capability of LiNbO 3 -coated Li 3 VO 4 as anode material for lithium-ion battery

Lithium vanadate (Li 3 VO 4 ) has garnered considerable attention as an alternative negative electrode material for non-aqueous lithium-ion batteries due to its high capacity, energy efficiency, and stable discharge voltage. Nonetheless, the Li 3 VO 4 material displays a low rate capability, attributed mainly to its poor intrinsic electronic conductivity. Here, in this study, we report the synthesis of lithium niobate LiNbO 3 -coated Li 3 VO 4 (LVO@LNO) using a one-pot sol-gel method. The resulting LVO@LNO demonstrates a high reversible capacity of approximately 530 mAh/g, which is more than double that of free Li 3 VO 4 . To explore the effect of the LNO coating process on the morphological and structural properties, Raman, XRD, operando XRD, XPS, SEM and HTEM analyses were conducted. To explain the enhancement of electronic conductivity in our modified material after a LiNbO 3 coating, we conducted an Ex-Situ electrochemical impedance (EIS) and Density Functional Theory (DFT) computational study. Additionally, we designed a full cell utilizing a 1 wt% LNO-coated LVO anode and NMC-811 cathode. The cell yielded an output voltage of approximately 2.8 V with a high initial specific capacity of 350 mAh/g versus to the anode, at 1C with a capacity retention of 85 % after 100 cycles.

25 ENERGY STORAGE↗

Convergent use of phosphatidic acid for hepatitis C virus and SARS-CoV-2 replication organelle formation

Double membrane vesicles (DMVs) serve as replication organelles of plus-strand RNA viruses such as hepatitis C virus (HCV) and SARS-CoV-2. Viral DMVs are morphologically analogous to DMVs formed during autophagy, but lipids driving their biogenesis are largely unknown. Here we show that production of the lipid phosphatidic acid (PA) by acylglycerolphosphate acyltransferase (AGPAT) 1 and 2 in the ER is important for DMV biogenesis in viral replication and autophagy. Using DMVs in HCV-replicating cells as model, we found that AGPATs are recruited to and critically contribute to HCV and SARS-CoV-2 replication and proper DMV formation. An intracellular PA sensor accumulated at viral DMV formation sites, consistent with elevated levels of PA in fractions of purified DMVs analyzed by lipidomics. Apart from AGPATs, PA is generated by alternative pathways and their pharmacological inhibition also impaired HCV and SARS-CoV-2 replication as well as formation of autophagosome-like DMVs. These data identify PA as host cell lipid involved in proper replication organelle formation by HCV and SARS-CoV-2, two phylogenetically disparate viruses causing very different diseases, i.e. chronic liver disease and COVID-19, respectively. Host-targeting therapy aiming at PA synthesis pathways might be suitable to attenuate replication of these viruses.

60 APPLIED LIFE SCIENCES↗

Controlled Fabrication of Quality ZnO NWs/CNTs and ZnO NWs/Gr Heterostructures via Direct Two-Step CVD Method

A novel and advanced approach of growing zinc oxide nanowires (ZnO NWs) directly on single-walled carbon nanotubes (SWCNTs) and graphene (Gr) surfaces has been demonstrated through the successful formation of 1D–1D and 1D–2D heterostructure interfaces. The direct two-step chemical vapor deposition (CVD) method was utilized to ensure high-quality materials’ synthesis and scalable production of different architectures. Iron-based universal compound molecular ink was used as a catalyst in both processes (a) to form a monolayer of horizontally defined networks of SWCNTs interfaced with vertically oriented ZnO NWs and (b) to grow densely packed ZnO NWs directly on a graphene surface. We show here that our universal compound molecular ink is efficient and selective in the direct synthesis of ZnO NWs/CNTs and ZnO NWs/Gr heterostructures. Heterostructures were also selectively patterned through different fabrication techniques and grown in predefined locations, demonstrating an ability to control materials’ placement and morphology. Several characterization tools were employed to interrogate the prepared heterostructures. ZnO NWs were shown to grow uniformly over the network of SWCNTs, and much denser packed vertically oriented ZnO NWs were produced on graphene thin films. Such heterostructures can be used widely in many potential applications, such as photocatalysts, supercapacitors, solar cells, piezoelectric or thermal actuators, as well as chemical or biological sensors.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Intense Pulse Light Annealing of Perovskite Photovoltaics Using Gradient Flashes

Perovskite solar cells (PSCs) have been fabricated through high-speed and low-cost depositions but often require long annealing. Intense pulse light (IPL) can anneal thin films in seconds after deposition by inducing very high temperatures lasting for milliseconds, and multiple flashes can be used to tune the temperature profile. In this study, a gradient flash annealing (GFA) approach is introduced and compared to uniform flash annealing (UFA) by investigating the crystallinity, morphology, and phase evolution of the CH 3 NH 3 PbI 3 perovskite films and their impact on PSC performance. Unlike UFA, low-intensity pulsed irradiation during the pre-annealing stage of GFA played a significant role on enhancing the PSC performance by forming pure-phase CH 3 NH 3 PbI 3 perovskite thin films with superior morphology and high crystallinity. To understand the kinetics, a transient thermal simulation using ANSYS was developed and confirmed with an experimental setup. The results combined with microscopy and spectrophotometry were used to visualize how duration, delay time, photon flux, and flash count parameters participated in crystallization, phase, and morphology evolution. The IPL annealing induced rapid surface temperature increase, reaching as high as 800 °C, while produced well-developed and bound perovskite grains without any surface defects in an uncontrolled ambient environment with high humidity (>60%). The study resulted in PSCs with maximum efficiency and fill factor of 9.27 and 69.92% for the UFA and 11.75 and 68% when annealed through the GFA approach, respectively. Lastly, this work utilized IPL as the sole thermal source for post-deposition annealing to rapidly fabricate efficient PSCs in only 10 s, which opens the pathway for high-speed, low-cost, and large-scale automated fabrication of perovskite photovoltaics and semiconductors.

14 SOLAR ENERGY↗

Corrosion of novel reactive silver ink and commercial silver-based metallizations in diluted acetic acid

Silver-based metallizations in photovoltaic modules are susceptible to corrosion by acetic acid generated in ethylene vinyl acetate encapsulated modules, resulting in power losses over time. Here, three silver-based metallizations are exposed to diluted acetic acid, in concentrations representative of that found in field-exposed modules. Compositional, morphological, and structural changes of the metallizations are studied over 3000 h of exposure to diluted acetic acid using Raman spectroscopy mapping, X-ray diffraction, and scanning electron microscopy. The three metallizations studied are: 1) a commercial high-temperature fire-through Ag paste, commonly used for Si diffused junction solar cells; 2) a commercial low-temperature paste normally used for silicon heterojunction cells; and 3) a novel low-temperature reactive silver ink shown to be suitable for photovoltaic applications. We find distinct corrosion rates for the high-temperature silver paste and reactive silver ink in the presence of diluted acetic acid. However, the low-temperature silver paste appears to be more corrosion resistant, likely due to a polymer layer that protects the silver particles.

36 MATERIALS SCIENCE↗

Phase stability of a eutectic high entropy alloy under extremes of pressures and temperatures

Additively manufactured high-entropy alloys are of interest because of their unique combination of high yield strength and large ductility achieved with far-from-equilibrium crystalline phases and micro/nanostructure morphology. We report on the phase transformation and thermal equation of state of the eutectic high-entropy alloy (EHEA) Al 18 Co 20 Cr 10 Fe 10 Ni 40 W 2 , produced by laser powder-bed fusion (L-PBF). The EHEA was studied in a large-volume Paris–Edinburgh cell using energy-dispersive x-ray diffraction to a pressure of 5.5 GPa and a temperature of 1723 K. Static compression studies in diamond anvil cells using angle-dispersive x-ray diffraction extended the high-pressure structural data to 317 GPa at ambient temperature. The initial dual-phase nanolamellar face-centered cubic (FCC) and body-centered cubic (BCC) structure of Al 18 Co 20 Cr 10 Fe 10 Ni 40 W 2 transforms into a single FCC phase under high pressure, with the BCC-to-FCC phase transformation completing at 9 ± 2 GPa. The FCC phase remained stable up to the highest pressure of 317 GPa. The measured thermal equation of state for the FCC phase of Al 18 Co 20 Cr 10 Fe 10 Ni 40 W 2 is presented up to 5.5 GPa and 1473 K. We observed melting of the EHEA at 1698 ± 25 K at a pressure of 5.5 GPa, and the recrystallized sample shows an increased fraction of the CsCl-type (B2) phase at ambient conditions following release from the high-pressure high-temperature state. The BCC-to-FCC phase transition completion pressure is correlated with the nanolamellae thickness of the BCC layer in this diffusion-less transformation at ambient temperature.

36 MATERIALS SCIENCE↗

Biofouling of filtration membranes in wastewater reuse: In situ visualization with confocal laser scanning microscopy

The filtration membranes utilized in advanced treatment of municipal wastewater are prone to biological fouling. Permeability loss and water recovery limitations due to fouling necessitate additional pretreatment and membrane cleaning, which raise the cost of water reuse. Better fouling mitigation calls for a deeper understanding of biofilm behavior on water reuse membranes. This study uses confocal microscopy to monitor biofouling under realistic conditions. To simulate water reuse, a miniature flow cell with microfiltration and ultrafiltration membranes was operated under typical filtration conditions using secondary effluent from California's East Bay Municipal Utility District. The growing biofilms were stained for extracellular polymeric substances and live and dead cells, and they were monitored in situ under filtration conditions with a confocal laser scanning microscope to produce 2-D and 3-D images. In situ image series revealed biofilm growth and removal processes including internal and external fouling, extracellular polymeric substance production, wrinkling, delamination, and film re-deposition. Additionally, changes in biofilm morphology between in situ and ex situ images highlighted limitations of ex situ imaging. Here, these results provide insight into the physical and biological mechanisms of biofouling in hopes of informing the development of improved techniques for biofouling mitigation.

ultrafiltration↗

Electrode roughness dependent electrodeposition of sodium at the nanoscale

Na metal is an attractive anode material for rechargeable Na ion batteries, however, the dendritic growth of Na can cause serious safety issues. Along with modifications of solid-electrolyte interphase (SEI), engineering the electrode has been reported to be effective in suppressing Na dendritic growth, likely by reducing localized current density accumulation. However, fundamental understanding of Na growth at the nanoscale is still limited. Here, we report an in-situ study of Na electrodeposition in electrochemical liquid cells with the electrodes in different surface roughness, e.g., flat or sharp curvature. Real time observation using transmission electron microscopy (TEM) reveals the Na electrodeposition with remarkable details. Relatively large Na grains (in the micrometer scale) are achieved on the flat electrode surface. The local SEI thickness variations impact the growth rate, thus the morphology of individual grains. In contrast, small Na grains (in tens of nanometers) grow explosively on the electrode at the point with sharp curvature. The newly formed Na grains preferentially deposit at the base of existing grains close to the electrode. Further studies using continuum-based computational modeling suggest that the growth mode of an alkali metal (e.g. Na) is strongly influenced by the transport properties of SEI. Our direct observation of Na deposition in combination with the theoretical modeling provides insights for comprehensive understanding of electrode roughness and SEI effects on Na electrochemical deposition.

25 ENERGY STORAGE↗

Modeling and mitigating fouling of microfiltration membranes for microalgae dewatering

Dewatering is energy-intensive for microalgae production, and microfiltration (MF) membranes are attractive because of their high energy efficiency. However, the membranes suffer from fouling by organic matter in the algae solutions, and there needs fundamental understanding of membrane fouling with actual algae solutions. Herein we thoroughly evaluate the dewatering performance of commercial polyethersulfone (PES) MF membranes using an integrated experiment and modeling approach. The effect of algae concentration, testing time, feed flow rate, and chemical cleaning on the dewatering performance and fouling-layer morphology are investigated. The fouling behavior can be successfully described using the Hermia and gel layer models with a gel concentration of 48 g/L for algae solutions. Furthermore, the PES membrane surface was grafted with hydrophilic zwitterions, which mitigated the fouling. For example, when challenged with 10 g/L algae solution in dead-end cells, the pristine and modified membrane exhibit water permeance of 80 and 170 L m – 2 h –1 bar –1 , respectively. Finally, three cycles of dewatering and NaOH cleaning were performed to demonstrate the promise of the MF membranes for practical dewatering application.

42 ENGINEERING↗

Colloidal Quantum Shells: An Emerging 2D Semiconductor for Energy Applications

Low-dimensional semiconductors hold strong promise for future energy applications. These nanomaterials are inexpensive to process and offer a broad spectrum of attractive quantum-mechanical properties. The notorious problem of low-dimensional nanostructures, however, lies in their limited performance under high energetic loads, when more than one exciton per particle is created. Multiple excitons undergo fast annihilation, causing efficiently roll-off in energy-intensive applications, including high-brightness LEDs, X-ray scintillators, and solar cells. In this prospective, we will highlight an emerging type of low-dimensional semiconductors that allows avoiding such multi-exciton (MX) energy losses. Recently demonstrated colloidal quantum shells benefit from the spatial separation of multiple excitons, which leads to extraordinary improvements to MX lifetimes and MX quantum yield. This makes quantum shell morphology an attractive candidate for solution-processed optical and electrical devices. In this Focus Review, we compare the optoelectronic properties of quantum shells against other low-dimensional semiconductors and discuss their emerging opportunities in solid-state lighting and energy-harvesting applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Dynamic disulfide bond networks enable self-healable and mechanically resilient intrinsically stretchable organic solar cells

A dynamic disulfide network introduced into donor/acceptor blends enables room-temperature self-healing and mechanical resilience in intrinsically stretchable organic solar cells, achieving performance recovery after high mechanical strain. The development of intrinsically stretchable organic solar cells (IS-OSCs) faces significant challenges in balancing mechanical durability and optoelectronic performance. Conventional π-conjugated polymer-based donor/acceptor blend films often exhibit limited stretchability and irreversible performance degradation under mechanical strain. To address these limitations, we propose a novel self-healable donor/acceptor blended film with a dual-network morphology, achieved by incorporating a dynamic disulfide bond-based crosslinked network into the bulk-heterojunction film. The resulting thin films demonstrate a power conversion efficiency (PCE) of 16.39% in rigid OSC devices and a fracture strain of 15.6%. Remarkably, the IS-OSCs retain 80% of their initial PCE under 30% strain and exhibit performance recovery after multiple stretch-release cycles at 40% strain through a room-temperature self-healing process. This work provides a proof-of-concept for highly stretchable and durable IS-OSCs, offering valuable insights for advancing the field of wearable energy systems, adaptive solar textiles, and sustainable electronics.

Yang, Wenyu↗

Monitoring the compaction of single DNA molecules in Xenopus egg extract in real time

DNA compaction is required for the condensation and resolution of chromosomes during mitosis, but the relative contribution of individual chromatin factors to this process is poorly understood. We developed a physiological, cell-free system using high-speed Xenopus egg extracts and optical tweezers to investigate real-time mitotic chromatin fiber formation and force-induced disassembly on single DNA molecules. Compared to interphase extract, which compacted DNA by ~60%, metaphase extract reduced DNA length by over 90%, reflecting differences in whole-chromosome morphology under these two conditions. Depletion of the core histone chaperone ASF1, which inhibits nucleosome assembly, decreased the final degree of metaphase fiber compaction by 29%, while depletion of linker histone H1 had a greater effect, reducing total compaction by 40%. Compared to controls, both depletions reduced the rate of compaction, led to more short periods of decompaction, and increased the speed of force-induced fiber disassembly. In contrast, depletion of condensin from metaphase extract strongly inhibited fiber assembly, resulting in transient compaction events that were rapidly reversed under high force. Altogether, these findings support a speculative model in which condensin plays the predominant role in mitotic DNA compaction, while core and linker histones act to reduce slippage during loop extrusion and modulate the degree of DNA compaction.

59 BASIC BIOLOGICAL SCIENCES↗

Significant Efficiency Enhancements in Non‐Y Series Acceptors by the Addition of Outer Side Chains

Abstract Most current highly efficient organic solar cells utilize small molecules like Y6 and its derivatives as electron acceptors in the photoactive layer. In this work, a small molecule acceptor, SC8‐IT4F, is developed through outer side chain engineering on the terminal thiophene of a conjugated 6,12‐dihydro‐dithienoindeno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (IDTT) central core. Compared to the reference molecule C8‐IT4F, which lacks outer side chains, SC8‐IT4F displays notable differences in molecule geometry (as shown by simulations), thermal behavior, single‐crystal packing, and film morphology. Blend films of SC8‐IT4F and the polymer donor PM6 exhibit larger carrier mobilities, longer carrier lifetimes, and reduced recombination compared to C8‐IT4F, resulting in improved device performance. Binary photovoltaic devices based on the PM6:SC8‐IT4F films reveal an optimal efficiency over 15%, which is one of the best values for non‐Y type small molecule acceptors (SMAs). The resultant devices also show better thermal and operational stability than the control PM6:L8‐BO devices. SC8‐IT4F and its blend exhibit a higher relative degree of crystallinity and π coherence length, compared to C8‐IT4F samples, beneficial for charge transport and device performance. The results indicate that outer side chain engineering on existing small electron acceptors can be a promising molecular design strategy for further pursuing high‐performance organic solar cells.

He, Qiao [Department of Chemistry and Centre for P↗

A novel approach to identify the ionomer phase in PEMFC by EELS

Proton exchange membrane fuel cells are one of the most promising technologies of energy conversion for both automotive and stationary applications, due to their ultimate cleanness and high efficiency. A critical factor, which strongly affects the fuel cell performance, is the ionomer distribution and coverage over the carbon support, since the catalysts, which are typically Pt and/or Pt-alloy nanoparticles, must be located at the carbon support/ionomer interface to catalyze the sluggish oxygen reduction reaction. However, the characterization and identification of the ionomer film, in terms of ionomer distribution and coverage over the carbon surface, is a long standing challenge. This is because the ionomer film may suffer from beam damage during the characterization, either from x-rays, neutrons or an electron beam, which causes morphological changes. In this regard, we report here a novel approach to identify and differentiate the ionomer, using the carbon signal produced by STEMEELS. Using this approach, not only the ionomer distribution, but also the carbon support distribution, can be probed at high spatial resolutions. In addition, this new approach allows us to identify ionomer-rich and carbon-support rich regions, which are quite challenging to determine using other methods.

08 HYDROGEN↗

Air-stable ternary organic solar cells achieved by using fullerene additives in non-fullerene acceptor-polymer donor blends

Organic solar cells (OSCs) based on donor–acceptor blends have shown a rapid improvement in power conversion efficiency (PCE) now approaching, for small cells, those of the state-of-the art commercial solar modules. However, performance degradation remains one of the most critical impediments for OSC technology commercialization. Ternary solar cells where a third component, for instance an acceptor, is added to a non-fullerene acceptor–polymer donor blend are an effective approach for improving both OSC efficiency and long-term stability. Here, in this work, we study the role of two fullerene acceptors, ET18 and PCBM, as the third component in P D :Y6 blends. These fullerene derivatives significantly enhance the cell stability, which retained >90% of their initial PCEs (13–14%) even after storage in air for 6 months, compared to only ~20% retention for the binary devices. GIWAXS, AFM, in situ impedance spectroscopy and femtosecond transient absorption spectroscopy measurements reveal that the enhanced stability of the ternary devices results from a more robust blend morphology reducing charge recombination in the ternary devices during aging.

14 SOLAR ENERGY↗

Activating magnetite ores for aqueous ironmaking at high current densities

Low-temperature electrochemical cells reducing iron oxides to metal in alkaline electrolytes can support fully electrified steelmaking processes. Previous studies on these cells have primarily focused on high-surface-area hematite, Fe 2 O 3 , reactants whereas attempts to reduce suspensions of magnetite, Fe 3 O 4 —one of the two feedstocks for existing ironmaking reactors—have generally been limited to low rates of reaction (<30 mA cm −2 ). Here, in this study, we control the crystalline domain size of Fe 2 O 3 and Fe 3 O 4 particles in 10 M NaOH electrolytes to study how the nanoscale morphology of oxides controls the rate of electrochemical ironmaking. Rotating-ring disk electrode measurements of Fe 2+ , in situ Raman spectroscopy of the electrode surface, and ex situ electron microscopy were consistent with a hypothesized passivation process at Fe 3 O 4 surfaces that may prevent the continuous formation of soluble intermediates. Sufficiently small (<100 nm diameter) oxide particles yielded Fe partial current densities >160 mA cm −2 , a fivefold increase relative to previously reported rates for Fe 3 O 4 suspensions and comparable to active Fe 2 O 3 . Electron microscopy revealed that electrodeposited films were composed of micron-scale crystalline Fe domains with a porous film of Fe 3 O 4 nanoparticles and supports a model where Fe is grown primarily from soluble Fe 2+ intermediates. Based on these insights, inactive blast-furnace-grade iron-oxides were transformed into high surface area nanoparticles (1.6 to 229.2 m 2 g −1 ) via reprecipitation, leading to a ninefold enhancement in faradaic efficiency and an Fe partial current density of 120 mA cm −2 . When integrated with chlor-iron cells producing reagents for reprecipitation, this approach could lead to a cost-competitive process for electrochemical ironmaking from industrially relevant feedstocks.

TEM↗

Electron‐Deficient and Quinoid Central Unit Engineering for Unfused Ring‐Based A 1 –D–A 2 –D–A 1 ‐Type Acceptor Enables High Performance Nonfullerene Polymer Solar Cells with High V oc and PCE Simultaneously

Abstract Here, a pair of A 1 –D–A 2 –D–A 1 unfused ring core‐based nonfullerene small molecule acceptors (NF‐SMAs), BO2FIDT‐4Cl and BT2FIDT‐4Cl is synthesized, which possess the same terminals (A 1 ) and indacenodithiophene unit (D), coupling with different fluorinated electron‐deficient central unit (difluorobenzoxadiazole or difluorobenzothiadiazole) (A 2 ). BT2FIDT‐4Cl exhibits a slightly smaller optical bandgap of 1.56 eV, upshifted highest occupied molecular orbital energy levels, much higher electron mobility, and slightly enhanced molecular packing order in neat thin films than that of BO2FIDT‐4Cl . The polymer solar cells (PSCs) based on BT2FIDT‐4Cl:PM7 yield the best power conversion efficiency (PCE) of 12.5% with a V oc of 0.97 V, which is higher than that of BO2FIDT‐4Cl ‐based devices (PCE of 10.4%). The results demonstrate that the subtle modification of A 2 unit would result in lower trap‐assisted recombination, more favorable morphology features, and more balanced electron and hole mobility in the PM7:BT2FIDT‐4Cl blend films. It is worth mentioning that the PCE of 12.5% is the highest value in nonfused ring NF‐SMA‐based binary PSCs with high V oc over 0.90 V. These results suggest that appropriate modulation of the quinoid electron‐deficient central unit is an effective approach to construct highly efficient unfused ring NF‐SMAs to boost PCE and V oc simultaneously.

Zhang, Chao↗

In-situ construction of ceria-metal/titanate heterostructure with controllable architectures for efficient fuel electrochemical conversion

Construction of ceria-metal/titanate heterostructure via exsolution is a promising strategy to improve the catalytic activity of titanate perovskites and broaden their applications in various energy conversion scenarios. However, the species exsolved after reduction are limited to reducible metal cations, such as Ni, Co, Fe, and precious metals. Herein, we report a modified exsolution approach for co-exsolving active oxides and metal nanoparticles from a titanate perovskite, La 0.8 Ce 0.1 Ni 0.4 Ti 0.6 O 3-δ (LCeNT). We highlight strained facet-specific CeO 2 cubes can be grown on the support after an air-annealing process with their morphology tunable by varying annealing temperature, whilst exsolution of Ni nanoparticles form subsequently following chemical/electrical reduction. An electrolyte-supported SOFC utilizing CeO 2 -Ni@LCeNT anode achieves maximum power density of 642 mW cm -2 at 900 °C in H 2 (~3% H 2 O). Exceptional robustness of the heterostructure is illustrated after running the cell in CH 4 (~3% H 2 O) for 20 h. Here this work demonstrates an intriguing pathway to constructing stable and active ceria-metal/titanate heterostructure for energy applications.

36 MATERIALS SCIENCE↗