Solar-driven enhanced chemical adsorption and interfacial evaporation using porous graphene-based spherical composites.

Solar-energy-driven water purification is a promising technology for obtaining clean water during the current global climate crisis. Solar absorbers with high light absorption capacity and efficient energy conversion are critical components of solar-driven water evaporation and purification systems. Herein, we demonstrate that porous reduced graphene oxide (rGO)-based composite spheres facilitate efficient water evaporation and effective organic pollutant adsorption from water. Most solar light (>99% for 1 mm thick composites) is absorbed by the porous rGO-based composite spheres floating on water and is subsequently converted into heat, which is efficiently transferred to water at the air-water interface. Evaporation efficiency via energy conversion by the floating sphere composites reaches ∼74%. The increase in surface temperature of water also contributes to improving the adsorption capacity of the rGO-based composite spheres for organic pollutants. Furthermore, the composites can effectively block ultraviolet radiation, preventing the chemical reaction of water pollutants into harmful components.

Controlling Graphene Wrinkles through the Phase Transition of a Polymer with a Low Critical Solution Temperature.

A novel method for controlling reduced graphene oxide (rGO) wrinkles through a phase transition in a solution using a low critical solution temperature (LCST) polymer dispersant has been developed. The polymer dispersant is designed by control of architecture and composition using reversible addition-fragmentation chain transfer polymerization. Synthesized poly(2-(dimethylaminoethyl) methacrylate-block-styrene) (PDbS) can be successfully functionalized on the rGO surface via noncovalent functionalization. PDbS-functionalized rGO (PDbS-rGO) exhibits good dispersibility in an aqueous phase at room temperature and forms wrinkles on the PDbS-rGO surface because of phase transition at the LCST of the polymer dispersant. The formation of PDbS-rGO wrinkles is controlled by varying the aggregation number of the polymer dispersant on the PDbS-rGO surface that strongly depends on temperature. This is confirmed by transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy (ID' /IG ratios are 0.560, 0.579, and 0.684, which correspond to 45, 70, and 95 °C, respectively). In addition, the mechanism of wrinkle control is proved by gold nanoparticles that are grown in polymer dispersant on the PDbS-rGO surface.

Lactobacillus Sps in Reducing the Risk of Diabetes in High-Fat Diet-Induced Diabetic Mice by Modulating the Gut Microbiome and Inhibiting Key Digestive Enzymes Associated with Diabetes.

Obesity caused by a high-fat diet (HFD) affects gut microbiota linked to the risk of type-2 diabetes (T2D). This study evaluates live cells and ethanolic extract (SEL) of Lactobacillus sakei Probio65 and Lactobacillus plantarum Probio-093 as natural anti-diabetic compounds. In-vitro anti-diabetic effects were determined based on the inhibition of α-glucosidase and α-amylase enzymes. The SEL of Probio65 and Probio-093 significantly retarded α-glucosidase and α-amylase enzymes (p < 0.05). Live Probio65 and Probio-093 inhibited α-glucosidase and α-amylase, respectively (p < 0.05). In mice fed with a 45% kcal high-fat diet (HFD), the SEL and live cells of both strains reduced body weight significantly compared to HFD control (p < 0.05). Probio-093 also improved blood glucose level compared to control (p < 0.05). The gut microbiota modulatory effects of lactobacilli on HFD-induced diabetic mice were analyzed with qPCR method. The SEL and live cells of both strains reduced phyla Deferribacteres compared to HFD control (p < 0.05). The SEL and live cells of Probio-093 promoted more Actinobacteria (phyla), Bifidobacterium, and Prevotella (genus) compared to control (p < 0.05). Both strains exerted metabolic-modulatory effects, with strain Probio-093 showing more prominent alteration in gut microbiota, substantiating the role of probiotics in gut microbiome modulations and anti-diabetic effect. Both lactobacilli are potential candidates to lessen obesity-linked T2D.

A Complementary Co-Ni Phosphide/Bimetallic Alloy-Interspersed N-Doped Graphene Electrocatalyst for Overall Alkaline Water Splitting.

Echinops-like bimetallic CoNiP-CoNi alloy is synthesized from a metal-organic framework (MOF) and serves as an efficient catalyst for the oxygen evolution reaction (OER), with a low overpotential of 300 mV in 1 M KOH at 10 mA cm-2 (η10 ). The cooperative effect of Ni and Co metal, as well as the interfacial properties of the integrated semiconducting phosphide/metallic alloy and electronic conductivity of the MOF-derived carbon regulate the performance of the catalyst. Moreover, the bimetallic CoNiP/CoNi alloy catalyst is interspersed with N-doped graphene, forming a triad catalyst that demonstrates superior activity towards the hydrogen evolution reaction (η10 =150 mV) and excellent durability, owing to interfacial effects of the triad catalyst, large electrochemical active surface area, and enhanced conductivity from N-doped graphene. The stability of the carbon-containing catalyst during OER (oxidation) is altered by the high reactivity of heteroatom dopant. The assembled CoNiP/CoNi/N-RGO||CoNiP/CoNi water electrolyzer delivers a reasonable cell potential of 1.76 V at 10 mA cm-2 . The synthesized bimetallic CoNiP/CoNi alloy-based triad catalyst thus demonstrates excellent electrocatalytic activity and high durability suitable for efficient alkaline water splitting.

Composition engineering of ZIF-derived cobalt phosphide/cobalt monoxide heterostructures for high-performance asymmetric supercapacitors.

The fabrication of interpenetrated heterostructures from desirable energy materials for the development of efficient supercapacitors is promising yet challenging. Herein, a leaf-shaped cobalt phosphide/cobalt oxide heterostructure, (CoPx)1-y/CoOy (0.44 > y > 0.06), was synthesized from 2D-zeolitic-imidazolate-framework (ZIF-Co-L) molecular precursor via phosphidation of the Co3O4 intermediate. The efficient construction of heterostructure through the variation of surface/bulk composition significantly alters the interfacial properties and electronic structure, yielding enhanced supercapacitor performance. Further, gas-phase phosphidation entails a core-shell formation mechanism via gas diffusion, regulated by the Kirkendall effect. The optimized heterostructure (y = 0.10) exhibits remarkable interfacial properties derived from the CoO/Co0/CoP interface, thus facilitating a high specific capacitance (467 F g-1 at 5 A g-1) and excellent cycling stability (~91% after 10000 cycles) at 30 A g-1. A further increase in the cyclability (~107%) was achieved by employing a graphene hybrid. Further, an asymmetric supercapacitor device was fabricated, that delivers reasonably high energy density of 12.7 Wh kg-1 at a power density of 370 W kg-1 and cycling stability of ~93% after 10000 cycles. This study reports on the modulation of interfacial properties of CoPx/CoO heterostructure to enhance energy storage performance via bulk/surface compositional variation, thereby providing a strategy to develop heterostructure electrodes for high-performance supercapacitor.

Scanty graphene-driven phase control and heteroatom functionalization of ZIF-67-derived CoP-draped N-doped carbon/graphene as a hybrid electrode for high-performance asymmetric supercapacitor.

Zeolitic imidazolate framework (ZIF)-derived materials have been explored as promising electrode for energy storage, owing to their tunable composition, high porous structure, and heteroatom-based active sites. Herein, we report cobalt phosphide-draped N-doped carbon/graphene hybrid (CoP-NPC/GS) synthesized from ZIF-67 precursor via a single-step in-situ carbonization and phosphidation. The CoP-NPC/GS hybrid performed as a promising positive electrode with superior electrochemical performance - high capacitance (165 F g-1 at 7 A g-1 compared to 97 F g-1 for CoP-NPC), enhanced rate capability, and promoted cycling stability (~88% after 10,000 cycles). Excellent performance of the CoP-NPC/GS was derived from scanty graphene (2 wt%)-driven compositional variation, which promotes the redox-active CoP phase and higher nitrogen content offering enhanced electronic conductivity. Besides, CoP-NPC/GS performed well as a negative electrode, derived from double-layer capacitance of porous carbon, realizing a capacitance of ~71 F g-1 at 1 A g-1 but inferior to CoP-NPC, which was regulated by pyridinic nitrogen-induced pseudocapacitance. A fabricated CoP-NPC/GS||CoP-NPC asymmetric device displayed an energy density of 10 Wh Kg-1 at 700 W kg-1, with excellent cyclability (~100%) till 11,000 cycles. This study clarifies the role of scanty graphene on the phase control and heteroatom functionalization of phosphide-based electrode, beneficial for enhanced supercapacitive performance.

Polymer wrapping-induced dispersion of single walled carbon nanotubes in ethylene glycol under mild sonication.

SWCNTs were individually dispersed in ethylne glycol (EG) via mild bath-type sonication using quaternized poly(furfuryl methacrylate)-co-(2-(dimethylamino)ethyl methacrylate) p(FMA-co-QDMAEMA) as a dispersing agent. QDMAEMA, which has alkyl groups, was more favorable to the dispersion ability of single walled carbon nanotubes (SWCNTs). The dispersion mechanism of SWCNTs in EG via helical wrapping of polymer chains along their sidewalls was suggested based on transmission electron microscopic observation.

Electrochemical Characteristics of All-Solid Lithium Ion Battery with Lithium Titanate/Lithium Lanthanum Zirconium Oxide Composite Electrode.

Composite anodes for all solid-state lithium secondary batteries based on lithium titanate (Li4Ti5O12) were fabricated by a wet process. The effect of the content of polyethylene oxide in the lithium titanate composite anode on the interfacial control for enhancing the ionic conductivity and binding between the constituent materials in the electrode was examined. The content of Super-P and garnet-type lithium lanthanum zirconium oxide in the composite lithium titanate electrode was fixed and the electrochemical characteristics of a half-cell were evaluated as a function of the lithium titanate and polyethylene oxide content in the electrode, where the polyethylene oxide content was varied from 35-70 wt%. A maximum discharge capacity of about 160 mAh g-1 was obtained with the electrode comprising lithium titanate, lithium lanthanum zirconium oxide, Super-P, and polyethylene oxide in a weight ratio of 40:10:10:40. This value is about 94% of the theoretical capacity (170 mAh g-1) of the lithium titanate electrode, and was almost equal to the half-cell capacity of the liquid-type congener. Furthermore, when this composite lithium titanate electrode was fabricated and evaluated in the full cell of an all-solid lithium secondary battery, a discharge capacity of about 140 mAh g-1 was obtained.

The intertwine of nanotechnology with the food industry.

The past decade has proven the competence of nanotechnology in almost all known fields. The evolution of nanotechnology today in the area of the food industry has been largely and has had a lot of contribution in the food processing, food package, and food preservation. The increasing global human population has come with growing population to be fed, and food production is not adjusted to at par with the growing population. This mismatch has shown the real essence of food preservation so that food products can reach to people on a global scale. The introduction of nanotechnology in the food industry has made it easy to transport foods to different parts of the world by extending the shelf-life of most food products. Even with this beneficial aspect of nanotechnology, it has not been proven an entire full-proof measure, and the field is still open to changing technology. It suffices to note that nanotechnology has to a big extent succeed in curbing the extent of food wastage due to food spoilage by the microbial infestation. Nanotechnology has focused on fresh foods, ensuring a healthier food by employing nano-delivery systems in the process. The delivery systems are the ones, which carries the food supplements. However, these are certain sets of regulations that must be followed to tame or control the health related risks of nanotechnology in food industries. This paper outlines the role of nanotechnology at different levels of the food industry including, packaging of food, processing of food and the various preservation techniques all aiming to increase the shelf life of the food products.

Three-Dimensional Porous Nitrogen-Doped NiO Nanostructures as Highly Sensitive NO2 Sensors.

Nickel oxide has been widely used in chemical sensing applications, because it has an excellent p-type semiconducting property with high chemical stability. Here, we present a novel technique of fabricating three-dimensional porous nitrogen-doped nickel oxide nanosheets as a highly sensitive NO2 sensor. The elaborate nanostructure was prepared by a simple and effective hydrothermal synthesis method. Subsequently, nitrogen doping was achieved by thermal treatment with ammonia gas. When the p-type dopant, i.e., nitrogen atoms, was introduced in the three-dimensional nanostructures, the nickel-oxide-nanosheet-based sensor showed considerable NO2 sensing ability with two-fold higher responsivity and sensitivity compared to non-doped nickel-oxide-based sensors.

Patterned transparent electrode with a continuous distribution of silver nanowires produced by an etching-free patterning method.

The outstanding electrical, optical, and mechanical properties of silver nanowire transparent electrodes are attractive for use in many optoelectronic devices, and the recent developments related to these electrodes have led to their commercialization. To more fully utilize the advantages of this technology, developing new process technologies in addition to performance improvements is important. In this report, we propose a novel ultra-simple patterning technology to generate a silver nanowire transparent layer and a unique patterned structure with continuously distributed silver nanowires without any etched areas. The patterning is conducted by exposure to ultraviolet light and rinsing. The exposed and unexposed regions of the resulting layer have dramatically different electrical conductivities, which produces an electrical pathway without using any etching or lift-off processes. The unique patterned structure produced by this etching-free method creates hardly any optical difference between the two regions and results in excellent visibility of the patterned transparent electrode layer.

Exposure monitoring of graphene nanoplatelets manufacturing workplaces.

Graphenes have emerged as a highly promising, two-dimensional engineered nanomaterial that can possibly substitute carbon nanotubes. They are being explored in numerous R&D and industrial applications in laboratories across the globe, leading to possible human and environmental exposures to them. Yet, there are no published data on graphene exposures in occupational settings and no readily available methods for their detection and quantitation exist. This study investigates for the first time the potential exposure of workers and research personnel to graphenes in two research facilities and evaluates the status of the control measures. One facility manufactures graphene using graphite exfoliation and chemical vapor deposition (CVD), while the other facility grows graphene on a copper plate using CVD, which is then transferred to a polyethylene terephthalate (PET) sheet. Graphene exposures and process emissions were investigated for three tasks - CVD growth, exfoliation, and transfer - using a multi-metric approach, which utilizes several direct reading instruments, integrated sampling, and chemical and morphological analysis. Real-time instruments included a dust monitor, condensation particle counter (CPC), nanoparticle surface area monitor, scanning mobility particle sizer, and an aethalometer. Morphologically, graphenes and other nanostructures released from the work process were investigated using a transmission electron microscope (TEM). Graphenes were quantified in airborne respirable samples as elemental carbon via thermo-optical analysis. The mass concentrations of total suspended particulate at Workplaces A and B were very low, and elemental carbon concentrations were mostly below the detection limit, indicating very low exposure to graphene or any other particles. The real-time monitoring, especially the aethalometer, showed a good response to the released black carbon, providing a signature of the graphene released during the opening of the CVD reactor at Workplace A. The TEM observation of the samples obtained from Workplaces A and B showed graphene-like structures and aggregated/agglomerated carbon structures. Taken together, the current findings on common scenarios (exfoliation, CVD growth, and transfer), while not inclusive of all graphene manufacturing processes, indicate very minimal graphene or particle exposure at facilities manufacturing graphenes with good manufacturing practices.

Fabrication of flexible, transparent and conductive films from single-walled carbon nanotubes with high aspect ratio using poly((furfuryl methacrylate)-co-(2-(dimethylamino)ethyl methacrylate)) as a new polymeric dispersant.

We synthesized poly((furfuryl methacrylate)-co-(2-(dimethylamino)ethyl methacrylate)) (p(FMA-co-DMAEMA)) for the dispersion of single-walled carbon nanotubes (SWCNTs) while maintaining their high aspect ratios. The nanotubes' length and height were 2.0 µm and 2 nm, as determined by transmission electron microscopy and atomic force microscopy, respectively. Transparent conductive films (TCFs) were fabricated by individually dispersed long SWCNTs onto a flexible polyethylene terephthalate substrate. The sheet resistance (Rs) was 210 Ω â–¡(-1) with 81% transmittance at a wavelength of 550 nm. To reduce their Rs, the TCFs were treated with HNO3 and SOCl2. After treatment, the TCFs had an Rs of 85.75 Ω â–¡(-1) at a transmittance of 85%. The TCFs exhibited no appreciable change over 200 repeated bending cycles. Dispersing SWCNTs with this newly synthesized polymer is an effective way to fabricate a transparent, highly conductive and flexible film.

Liquid-phase exfoliation of expanded graphites into graphene nanoplatelets using amphiphilic organic molecules.

Graphenes with a two-dimensional lattice of carbons have been widely employed in diverse applications owing to their excellent electrical, thermal, mechanical, and gas-barrier properties. However, the frequently-used reduced graphene oxide (rGO), which is synthesized from natural graphites by strong oxidation and subsequent reduction via highly toxic components, exhibits imperfect characteristics because of remaining defect sites on its basal planes. Therefore, in this work, we present a convenient way to prepare graphene nanoplatelets (GNPs) with minimized defect sites on their basal planes employing liquid-phase exfoliation of edge-functionalized expanded graphites (EGs) with amphiphilic organic molecules. Exfoliated GNPs revealed approximately sub-7-nm-thickness and showed stable dispersibility in an organic media during 9 months. Furthermore, spray-coated GNP films presented homogeneously stacked morphologies without noticeable agglomerations.

Electrically conductive epoxy nanocomposites with expanded graphite/carbon nanotube hybrid fillers prepared by direct hybridization.

Carbon nanotubes (CNTs) are generally used to promote the electrical conductivity of the polymer nanocomposites. However, in spite of their superior properties, CNT's high cost has limited their commercial application, so far. Thus, the development of hybrid carbon nanomaterials (CNMs) composed of CNTs and cheaper CNMs such as carbon fibers (CFs), expanded graphites (EGs), and graphene nanoplatelets (GNPs) is important in terms of reducing the cost of CNT-based fillers. In this study, we prepared EG/CNT hybrid fillers via direct CNT synthesis on the EG support using modified combustion method and thermal chemical vapor deposition (CVD) method, and investigated the electrical conductivity of the expoxy nanocomposite with EG/CNT hybrid fillers. The epoxy nanocomposites with EG/CNT hybrid fillers at 20 wt% filler loading showed 260% and 170% electrical conductivity enhancement in comparison with the EG and the simply mixed EG and CNT fillers, respectively. Our approach provides various applications including electromagnetic interference (EMI) shielding materials, thermal interface materials (TIMs), and reinforced nanocomposites.

In/Ga-free, inkjet-printed charge transfer doping for solution-processed ZnO.

An In/Ga-free doping method of zinc oxide (ZnO) is demonstrated utilizing a printable charge transfer doping layer (CTDL) based on (3-aminopropyl)triethoxysilane (APS) molecules. The self-assembled APS molecules placed on top of ZnO thin films lead to n-type doping of ZnO and filling shallow electron traps, due to the strong electron-donating characteristics of the amine group in APS molecules. The CTDL doping can tune the threshold voltage and the mobility of the ZnO thin-film transistors (TFTs) as one varies the grafting density of the APS molecules and the thickness of the underneath ZnO thin films. From an optimized condition, high-performance ZnO TFTs can be achieved that exhibit an electron mobility of 4.2 cm(2)/(V s), a threshold voltage of 10.5 V, and an on/off current ratio larger than 10(7). More importantly, the method is applicable to simple inkjet processes, which lead to produce high-performance depletion load ZnO inverters through selective deposition of CTDL on ZnO thin films.

Carbon hybrid fillers composed of carbon nanotubes directly grown on graphene nanoplatelets for effective thermal conductivity in epoxy composites.

Carbon nanomaterials are generally used to promote the thermal conductivity of polymer composites. However, individual graphene nanoplatelets (GNPs) or carbon nanotubes (CNTs) limit the realization of the desirable thermal conductivity of the composite in both through- and in-plane directions. In this work, we present the thermal conductivity enhancement of the epoxy composite with carbon hybrid fillers composed of CNTs directly grown on the GNP support. The composite with 20 wt% hybrid filler loading showed 300% and 50% through-plane thermal conductivity improvements in comparison with the individual CNTs and GNPs, respectively. Moreover, it showed an enhanced thermal conductivity of up to 12% higher than that of the simply mixed GNP and CNT fillers. In more detail, hybrid fillers, whose CNTs were synthesized on the GNP support (Support C, Fe/Mo-MgO:GNP=1:0.456) for 60 min via chemical vapor deposition process, presented the highest through-plane thermal conductivity of 2.41 W m-1 K-1 in an epoxy composite.

Efficiency enhancement in a-plane InGaN/GaN light emitters with carbon nanotubes.

This study investigates the coupling modes of a-plane InGaN/GaN mutiquantum wells (MQWs) with single-walled carbon nanotubes (SWCNTs). The enhancement of light emissions at resonance photon energies can be explained by the surface plasmon coupling of the MQW-SWCNT hybrid structure. The photoluminescence (PL) enhancement ratios of the indigo (2.90 eV) emission from MQWs with SWCNTs reveal three coupling modes at 2.50 eV, 2.97 eV, and 3.42 eV. In addition, the trend of the PL intensity ratios and efficiencies corresponds to that of the PL enhancement ratios. The PL efficiencies for the green (2.46 eV) and indigo (2.90 eV) emissions of SWCNT-coated MQWs are 32% and 110% better than the corresponding values of uncoated MQWs, respectively. The results show that the MQW-SWCNT hybrid structure has the potential to be applied in high-efficiency light emitters in the visible and ultraviolet range.

Improvement of SWCNT transparent conductive films via transition metal doping.

To realize transparent conductive films based on single-walled carbon nanotubes (SWCNTs), we applied a spray coating process with transition metal doping to SWCNT networks. Schottky contacts between metallic and semiconducting SWCNTs changed to Ohmic contacts due to the reduction of metals on the SWCNT surfaces via direct conversion from solution.

Transparent organic p-dopant in carbon nanotubes: bis(trifluoromethanesulfonyl)imide.

We propose bis(trifluoromethanesulfonyl)imide [(CF(3)SO(2))(2)N](-) (TFSI) as a transparent strong electron-withdrawing p-type dopant in carbon nanotubes (CNTs). The conventional p-dopant, AuCl(3), has several drawbacks, such as hygroscopic effect, formation of Au clusters, decrease in transmittance, and high cost in spite of the significant increase in conductivity. TFSI is converted from bis(trifluoromethanesulfonyl)amine (TFSA) by accepting electrons from CNTs, subsequently losing a proton as a characteristic of a Brønsted acid, and has an inductive effect from atoms with high electronegativity, such as halogen, oxygen, and nitrogen. TFSI produced a similar improvement in conductivity to AuCl(3), while maintaining high thermal stability, and no appreciable change in transmittance with no cluster formation. The effectiveness of TFSI was compared with that of other derivatives.