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At least 145 records · Page 8

Versatile coating with multifunctional performance for solar steam generation

In this work, a new kind of material, composite complex coating (CCC), with multifunctional performance has been developed for solar steam generation. The CCC has many advantages: (a) Scalability. The fabrication process is facile and mild; it can be realized in aqueous solution at room temperature, without high pressure, toxic organic solvents, or complex equipment. (b) Cost-effectiveness. The reagents used for preparation of CCC are low-cost and readily available. (c) Universality and stability. CCC firmly adheres on surfaces of various substrates with diverse shapes (cotton, filter paper, wood, polyurethane sponge, and even chemically inert and highly hydrophobic polyvinylidene fluoride membranes), and can withstand rinsing treatment (3000 r/min for 96 h), cyclic frost-thaw test (-18 °C ⇌ 30 °C, 90 times), and both high and low pH environments. In addition, many other reported coatings, such as carbon black, fail under similar process strain. (d) Anti-crude oil-fouling property. The CCC possesses stable superhydrophilicity and underwater superoleophobicity, which collectively endow substrates with the ability to resist fouling by oils. (e) Broad and strong light absorption. CCC can transform various substrates with diverse shapes into black materials with broadband light absorption due to its d-d transitions and rough surface. Together, these properties of CCC enable substrates with nearly any structural design to be easily transformed into photothermal materials for efficient solar steam generation. Furthermore, as a proof of concept, poplar wood is treated with CCC, achieving a water evaporation rate of ~1.8 kg m-2 h-1 (one sun), which is a record among wood-based photothermal materials.

14 SOLAR ENERGY↗

Multifunctional landscapes for dedicated bioenergy crops lead to low-carbon market-competitive biofuels

Switchgrass is a promising feedstock for cellulosic biorefineries, due to its ability to maintain comparatively high biomass yields across a wide range of soil and climatic conditions. However, there is an incomplete understanding of the economic and environmental tradeoffs associated with cultivating switchgrass on low-productivity land for conversion to biofuels. This study surveys prior literature and demonstrates a new integrated assessment framework, including agroecosystem, ecosystem services valuation, technoeconomic, and life-cycle assessment models, to quantify and contextualize the economic and environmental impacts of switchgrass cultivation on marginal land with downstream conversion to biofuels. Monetizing and incorporating the value of ecosystem services, such as improved water quality benefits from nitrate and sediment reductions, climate change mitigation benefits from CO 2 emission reduction, and recreational and pollination benefits from increased biodiversity, the modeled multifunctional landscape reduces the ethanol production cost by 33.3–58.9 cents/$\scriptsize{L}$-gasoline-equivalent ($\$$1.3–2.2/gge). Planting switchgrass in low productivity land improves soil health, resulting in the carbon footprint reduction credit of 12.8–20.2 gCO 2e /MJ. For an improved switchgrass-to-ethanol conversion pathway with the maximum benefits from ecosystem services, the minimum ethanol selling price and carbon footprint of ethanol, respectively, could reach to 31 cents/$\scriptsize{L}$-gasoline-equivalent (47% reduction relative to average gasoline price) and 3 gCO 2e /MJ (97% reduction relative to gasoline). In conclusion, this low carbon renewable ethanol leads to substantial State and/or Federal policy incentives (~$\$$1/$\scriptsize{L}$-gasoline-equivalent) providing a large benefit to biorefinery operators, farmers, and the public as a whole.

09 BIOMASS FUELS↗

Brain-implantable multifunctional probe for simultaneous detection of glutamate and GABA neurotransmitters

We report Glutamate (GLU) and gamma-aminobutyric acid (GABA) are neurotransmitters (NTs) with an essential role in signal transmission in the brain. Brain disorders, such as epilepsy, Alzheimer's and Parkinson's diseases, and traumatic brain injury can be linked to imbalances in the GLU-GABA homeostasis that occurs in sub-second to seconds time frames. Current measurement techniques can detect these two NT concentrations simultaneously only in vitro. The present work reports on the fabrication of a silicon multifunctional biosensor microarray probe for sub-second simultaneous GLU-GABA detection in real-time, with excellent analyte sensitivity and selectivity and in vivo capabilities. The novel Si probes feature four surface-functionalized platinum ultramicroelectrodes (UMEs) for simultaneous amperometric detection of GLU and GABA with a sentinel, and a built-in microfluidic channel for the introduction of neurochemicals in the proximity of the UMEs. The microchannel also allows functioning of an On-Demand In-situ Calibrator that runs in-situ biosensor calibration. The probe exhibited excellent robustness at insertion in agarose-gel brain-tissue-mimicking test, and remarkably high hydrogen peroxide sensitivity (a by-product of GLU-GABA enzyme biosensor) with values on the order of 5000 nA μM -1 cm -2 and maximum sensitivities of 204 ± 15 nA μM -1 cm -2 and 37 ± 7 nA μM -1 cm -2 for GLU and GABA, respectively. Furthermore, the limit of detection of the biosensors reached as low as 7 nM, 165 nM and 750 nM for H 2 O 2 , GLU and GABA, respectively and a temporal resolution of hundreds of milliseconds during in vivo studies using freely moving rats.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Thermodynamic Ground States of Multifunctional Metal Dodecaborides

A large class of metal dodecaborides (MB 12 ) is currently raising great expectations as multifunctional materials, but their refined structures are not fully resolved, which severely limits the understanding of structure–property relationships. In this paper, we report that the tetragonal tI26 structure is the thermodynamic ground state of ScB 12 , and we predict the tetragonal YB 12 , ZrB 12 , and HfB 12 to be metastable, whereas the cubic cF52 structure is the high-temperature phase of ScB 12 and represents the thermodynamic ground state of YB 12 , ZrB 12 , and HfB 12 . Crystal structures based on experimental synchrotron data are reported for tetragonal ScB 12 and cubic YB 12 , and high-temperature X-ray data prove the phase transformation into cubic ScB 12 . In both types of crystal structures, the most prominent feature is that the boron atoms are linked into a rigid three-dimensional network of interconnected, empty B 12 -cuboctahedra with metal atoms in large cages in form truncated octahedra consisting of 24 boron atoms. It is the uniqueness of these configurations that causes unusual functionalities, i.e., the coexistence of high hardness, low density, and good electrical conductivity. Furthermore, we elucidate that these physical properties are of electronic origins. These findings not only resolve the longstanding structural puzzle of this family of MB 12 but also provide crucial insights into the underlying nature of their remarkable properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Novel Layered Supercell Structure from Bi 2 AlMnO 6 for Multifunctionalities

Layered materials, e.g., graphene and transition metal (di)chalcogenides, holding great promises in nanoscale device applications have been extensively studied in fundamental chemistry, solid state physics and materials research areas. In parallel, layered oxides (e.g., Aurivillius and Ruddlesden–Popper phases) present an attractive class of materials both because of their rich physics behind and potential device applications. In this work, we report a novel layered oxide material with self-assembled layered supercell structure consisting of two mismatch-layered sublattices of [Bi 3 O 3+δ ] and [MO 2 ] 1.84 (M = Al/Mn, simply named BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made of a three-layer-thick Bi–O slab and a one-layer-thick Al/Mn–O octahedra slab in the out-of-plane direction. Strong room-temperature ferromagnetic and piezoelectric responses as well as anisotropic optical property have been demonstrated with great potentials in various device applications. Furthermore, the realization of the novel BAMO layered supercell structure in this work has paved an avenue toward exploring and designing new materials with multifunctionalities.

36 MATERIALS SCIENCE↗

High Efficiency Si Photocathode Protected by Multifunctional GaN Nanostructures

Photoelectrochemical water splitting is a clean and environmentally friendly method for solar hydrogen generation. Its practical application, however, has been limited by the poor stability of semiconductor photoelectrodes. In this work, we demonstrate the use of GaN nanostructures as a multifunctional protection layer for an otherwise unstable, low-performance photocathode. The direct integration of GaN nanostructures on n + -p Si wafer not only protects Si surface from corrosion but also significantly reduces the charge carrier transfer resistance at the semiconductor/liquid junction, leading to long-term stability (>100 h) at a large current density (>35 mA/cm 2 ) under 1 sun illumination. The measured applied bias photon-to-current efficiency of 10.5% is among the highest values ever reported for a Si photocathode. Here given that both Si and GaN are already widely produced in industry, our studies offer a viable path for achieving high-efficiency and highly stable semiconductor photoelectrodes for solar water splitting with proven manufacturability and scalability.

36 MATERIALS SCIENCE↗

Ultra-scalable Multifunctional Nanoengineered Cu and Al surfaces for anti-biofouling applications

Biofouling disrupts surface functionality and integrity of engineered substrates. A variety of natural materials such as plant leaves and insect wings have evolved sophisticated physical mechanisms capable of preventing biofouling. Over the past decade, several reports have pinpointed nanoscale surface topography as an important regulator of the surface adhesion and growth of bacteria. Although artificial nanoengineered features have been used to create bactericidal materials that kill adhered bacteria, functional surfaces capable of synergistically providing anti-biofouling and bactericidal properties remain to be developed. Furthermore,fundamental questions pertaining to the need for intrinsic hydrophobicity to achieve bactericidal performance or the crucial role played by structure length scale (nano vs. micro), remain to be answered. Here, we demonstrate highly scalable, cost effective, and efficient nanoengineered multifunctional surfaces that possess both anti-biofouling and bactericidal properties on industrially relevant copper (Cu) and aluminum (A1) substrates. We characterize biofouling and bactericidal performance using a combination of scanning electron microscopy (SEM), atomic force microscopy (AFM), live-dead bacterial staining and imaging, as well as solution phase measurements of bacterial viability. SEM results showed that nanostructures created on both Cuand Al were capable of physical deformation of adhered E. coli . Bacterial viability measurements on both Cu and Al indicated a complex interaction between the anti-biofouling and bactericidal nature of these materials and their surface topography, chemistry, and structure. We found that nano-length structures, as compared to micro-length, provide improved bactericidal properties,and that increased hydrophobicity greatly decreased the of adhered bacteria while also modestly increasing the surfaces killing capacity. This study provides additional insights into design guidelines for materials that are not only bactericidal, but also anti-biofouling, using a simple and economic method.

59 BASIC BIOLOGICAL SCIENCES↗

Exploring the Promise of Multifunctional “Zintl-Phase-Forming” Electrolytes for Si-Based Full Cells

Li-M-Si ternary Zintl phases have gained attention recently due to their high structural stability, which can improve the cycling stability compared to a bulk Si electrode. Adding multivalent cation salts (such as Mg 2+ and Ca 2+ ) in the electrolyte was proven to be a simple way to form Li-M-Si ternary phases in situ in Si-based Li-ion cells. To explore the promise of Zintl-phaseforming electrolytes, we systematically investigated their application in pouch cells via electrochemical and multiscale postmortem analysis. The introduction of multivalent cations, such as Mg 2+ , during charging can form Li x M y Si ternary phases. They can stabilize Si anions and reduce side reactions with electrolyte, improving the bulk stability. More importantly, Mg 2+ and Ca 2+ incorporate into interfacial side reactions and generate inorganic-rich solid- electrolyte interphase, thus enhancing the interfacial stability. Therefore, the full cells with Zintl-phase-forming electrolytes achieve higher capacity retentions at the C/3 rate after 100 cycles, compared to a baseline electrolyte. Additionally, strategies for mitigating the electrode-level fractures of Si were evaluated to make the best use of Zintl-phase-forming electrolytes. In conclusion, this work highlights the significance of synergistic impact of multifunctional additives to stabilize both bulk and interface chemistry in high-energy Si anode materials for Li-ion batteries.

25 ENERGY STORAGE↗

Multifunctional Effect of Fe Substitution in Na Layered Cathode Materials for Enhanced Storage Stability

In this study, developing stable cathode materials that are resistant to storage degradation is essential for practical development and industrial processing of Na-ion batteries, as many sodium layered oxide materials are susceptible to hygroscopicity and instability when exposed to ambient air. Among the various layered compounds, Fe-substituted O 3 -type Na(Ni 1/2 Mn 1/2 ) 1-x Fe x O 2 materials have emerged as a promising option for high-performance and low-cost cathodes. While previous reports have noted the decent air-storage stability of these materials, the role and origin of Fe substitution in improving storage stability remain unclear. In this study, we investigate the air resistant effect of Fe substitution in O 3 -Na(Ni 1/2 Mn 1/2 ) 1-x Fe x O 2 cathode materials by performing systematic surface and structural characterizations. We find that the improved storage stability can be attributed to the multifunctional effect of Fe substitution, which forms a surface protective layer containing an Fe-incorporated spinel phase and decreases the thermodynamical driving force for bulk chemical sodium extraction. With these mechanisms, the Fe-containing cathodes can suppress the cascades of cathode degradation processes and better retain the electrochemical performance after air storage.

25 ENERGY STORAGE↗

Roll-to-Roll Processing of Silicon Carbide Nanoparticle-Deposited Carbon Fiber for Multifunctional Composites

This work provides a proof of principle that a high volume, continuous throughput fiber coating process can be used to integrate semiconducting nanoparticles on carbon fiber surfaces to create multifunctional composites. By embedding silicon carbide nanoparticles in the fiber sizing, subsequent composite fabrication methods are used to create unidirectional fiber-reinforced composites with enhanced structural health monitoring (SHM) sensitivity and increased interlaminar strength. Additional investigations into the mechanical damping behavior of these functional composites reveal a significantly increased loss factor at the glass-transition temperature ranging from a 65 to 257% increase. Composites with both increased interlaminar strength and SHM sensitivity are produced from a variety of epoxy and silicon carbide nanoparticle concentrations. Overall, the best performing composite in terms of combined performance shows an increase of 47.5% in SHM sensitivity and 7.7% increase in interlaminar strength. Finally, this work demonstrates successful and efficient integration of nanoparticle synthesis into large-scale, structural applications.

36 MATERIALS SCIENCE↗

Multifunctional Liquid Marble Compound Lenses

Mosquito compound eyes are elaborate multifunctional hierarchical structures. The presence of ordered curved features spanning length scales of nanometers to millimeters provides the mosquito eye with a wide field of view, an infinite depth of field, as well as antifogging properties. Developing bio-inspired compound lenses is challenging because of the need to mimic all characteristic curvatures along with their functionalities. Herein, we show how the curvature inherent to nanoparticles, emulsion droplets, and liquid marbles can be employed to mimic the hierarchical structure and functionality of mosquito compound eyes. At the nanometers to micron length scale we employ nanoparticle-stabilized emulsion droplets of photocurable oil to form microlenses with nanoscale surface features. After polymerization, the microlenses form a monolayer on an oil droplet to create an optically clear, millimeter scale, liquid marble that functions as a compound lens. Here, we characterize the optical and surface properties of the compound lenses and find that they reproduce the functionality of the mosquito eye. Furthermore, we exploit the mobility and reconfigurability of liquid marbles to create arrays (centimeter scale) of compound lenses and other types of functional lenses such as the Janus lens that magnifies the image acquired by the compound lens. Simple and scalable methods to create compound lenses could aid in the development of miniaturized advanced vision systems.

36 MATERIALS SCIENCE↗

High Throughput Screening of 3D Printable Resins: Adjusting the Surface and Catalytic Properties of Multifunctional Architectures

Identification of 3D printable materials is crucial to expand the breadth of physical and chemical properties attainable by additive manufacturing. Stereolithography (SLA), a widespread 3D printing method based on resin photopolymerization, is ideally suited for exploring a large variety of monomers to produce functional three-dimensional solids of diverse properties. However, for most commercial SLA printers, screening monomers and resin compositions requires large volumes (~150 mL) in each printing cycle, making the process costly and inefficient. Herein, a high throughput block (HTB) adaptor was developed to screen arrays of monomers and resin compositions, consuming lower volumes (<2 mL) and less time per print (<1/16 based on a 4 × 4 matrix) than using the original hardware. By use of this approach, a library of materials with different surface hydrophobicities were 3D printed by including long chain acrylates in the resins. In addition, several metal salts were dissolved in an acrylic acid-based resin, 3D printed, and screened as benzyl alcohol oxidation catalysts. Cu(II)-based resins produced the most active structures. Combinations of Cu(II) and long chain acrylate monomers were then used to 3D print complex catalytic architectures with varying degrees of hydrophobicity. Linear relationships were observed between 3D printed surface area, surface hydrophobicity, and catalyst performance. For a high surface Schwarz P topology ca. 60% enhancement in the catalytic activity of Cu(II) was attained by replacing the parent resin with one containing hydrophobic isodecyl groups, indicating that the immediate environment of the catalytic site affected its performance. The HTB enables fast screening of resins for 3D printing multifunctional architectures with intrinsic catalytic activity, tunable surface properties, and minimal waste.

36 MATERIALS SCIENCE↗

Multifunctional Cellulolytic Enzymes Outperform Processive Fungal Cellulases for Coproduction of Nanocellulose and Biofuels

Producing fuels, chemicals, and materials from renewable resources to meet societal demands remains an important step in the transition to a sustainable, clean energy economy. The use of cellulolytic enzymes for the production of nanocellulose enables the coproduction of sugars for biofuels production in a format that is largely compatible with the process design employed by modern lignocellulosic (second generation) biorefineries. However, yields of enzymatically produced nanocellulose are typically much lower than those achieved by mineral acid production methods. In this study, we compare the capacity for coproduction of nanocellulose and fermentable sugars using two vastly different cellulase systems: the classical 'free enzyme' system of the saprophytic fungus, Trichoderma reesei (T. reesei) and the complexed, multifunctional enzymes produced by the hot springs resident, Caldicellulosiruptor bescii (C. bescii). Here, we demonstrate by comparative digestions that the C. bescii system outperforms the fungal enzyme system in terms of total cellulose conversion, sugar production, and nanocellulose production. In addition, we show by multimodal imaging and dynamic light scattering that the nanocellulose produced by the C. bescii cellulase system is substantially more uniform than that produced by the T. reesei system. These disparities in the yields and characteristics of the nanocellulose produced by these disparate systems can be attributed to the dramatic differences in the mechanisms of action of the dominant enzymes in each system.

09 BIOMASS FUELS↗

Cascade Reaction of Ethanol to Butadiene over Multifunctional Silica-Supported Ag and ZrO 2 Catalysts

Although butadiene is currently a by-product of naphtha cracking, interest in producing butadiene from bio-based ethanol has increased because of the lower environmental impact of the ethanol to butadiene reaction. Furthermore, this work explores a multifunctional catalyst system composed of silica-supported Ag and ZrO 2 used for the cascade reaction of ethanol to butadiene at 573 K. The Ag and ZrO 2 components were synthesized on separate support particles enabling characterization of each component without interference from the other. High selectivity to butadiene (65%) at high ethanol conversion (75%) was achieved with an appropriate ratio of Ag and ZrO 2 in the reactor. Silver catalyzed the initial dehydrogenation of ethanol to acetaldehyde while ZrO 2 catalyzed the C-C coupling and subsequent dehydration reactions. The silica-supported ZrO 2 exhibited superior selectivity relative to bulk ZrO 2 in the Ag-promoted ethanol to butadiene reaction. Results from Zr K-edge X-ray absorption spectroscopy and UV-Vis spectroscopy showed that ZrO 2 was highly dispersed on the silica support over a range of loadings. Infrared spectroscopy of adsorbed pyridine, CO, and CO 2 , and kinetics of probe reactions 1-butene double bond isomerization, 2-propanol decomposition, and ethanol hydrogenation of acetone were used to compare the acid-base nature and chemical reactivity of silica-supported ZrO 2 to bulk ZrO 2 .

09 BIOMASS FUELS↗

Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 ?C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites.

36 MATERIALS SCIENCE↗

Quest for Multifunctionality: Current Progress in the Characterization of Heterometallic Metal–Organic Frameworks

Metal–organic frameworks (MOFs) are a class of porous, crystalline materials that have been systematically developed for a broad range of applications. Incorporation of two or more metals into a single crystalline phase to generate heterometallic MOFs has been shown to lead to synergistic effects, in which the whole is oftentimes greater than the sum of its parts. Because geometric proximity is typically required for metals to function cooperatively, deciphering and controlling metal distributions in heterometallic MOFs is crucial to establish structure–function relationships. However, determination of short- and long-range metal distributions is nontrivial and requires the use of specialized characterization techniques. Advancements in the characterization of metal distributions and interactions at these length scales is key to rapid advancement and rational design of functional heterometallic MOFs. Further, this perspective summarizes the state-of-the-art in the characterization of heterometallic MOFs, with a focus on techniques that allow metal distributions to be better understood. Using complementary analyses, in conjunction with computational methods, is critical as this field moves toward increasingly complex, multifunctional systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Multifunctional Silicon Surfaces: Reaction of Dichlorocarbene Generated from Seyferth Reagent with Hydrogen-Terminated Silicon (111) Surfaces

Insertion of dichlorocarbene (:CCl2), generated by decomposition of the Seyferth reagent PhHgCCl2Br, into the Si-H bond of a tertiary silane to form a Si-CCl2H group is an efficient homogeneous, molecular transformation. A heterogeneous version of this reaction, between PhHgCCl2Br and a silicon (111) surface terminated by tertiary Si-H bonds, was studied using a combination of surface-sensitive infrared and X-ray photoelectron spectroscopies. The insertion of dichlorocarbene into surface Si-H bonds parallels the corresponding reaction of silanes in solution, to produce surface-bound dichloromethyl groups (Si-CCl2H) covering &sim;25% of the silicon surface sites. A significant fraction of the remaining Si-H bonds on the surface was converted to Si-Cl/Br groups during the same reaction, with PhHgCCl2Br serving as a halogen atom source. The presence of two distinct environments for the chlorine atoms (Si-CCl2H and Si-Cl) and one type of bromine atom (Si-Br) was confirmed by Cl 2p, Br 3d, and C 1s X-ray photoelectron spectroscopy. The formation of reactive, halogen-terminated atop silicon sites was also verified by reaction with sodium azide or the Grignard reagent (CH3MgBr), to produce Si-N3 or Si-Me functionalities, respectively. Thus, reaction of a hydrogen-terminated silicon (111) surface with PhHgCCl2Br provides a facile route to multifunctional surfaces possessing both stable silicon-carbon and labile silicon-halogen sites, in a single pot synthesis. The reactive silicon-halogen groups can be utilized for subsequent transformations and, potentially, the construction of more complex organic-silicon hybrid systems.

Liu, Wenjun↗

The links between ecosystem multifunctionality and above- and belowground biodiversity are mediated by climate

Plant biodiversity is often correlated with ecosystem functioning in terrestrial ecosystems. However, we know little about the relative and combined effects of above- and belowground biodiversity on multiple ecosystem functions (for example, ecosystem multifunctionality, EMF) or how climate might mediate those relationships. Here we tease apart the effects of biotic and abiotic factors, both above- and belowground, on EMF on the Tibetan Plateau, China. We found that a suite of biotic and abiotic variables account for up to 86% of the variation in EMF, with the combined effects of above- and belowground biodiversity accounting for 45% of the variation in EMF. Our results have two important implications: first, including belowground biodiversity in models can improve the ability to explain and predict EMF. Second, regional-scale variation in climate, and perhaps climate change, can determine, or at least modify, the effects of biodiversity on EMF in natural ecosystems.

59 BASIC BIOLOGICAL SCIENCES↗