Femtosecond Laser Irradiation as a Novel Method for Nanosheet Growth and Defect Generation in g-C3N4

Among the many recently developed photo-catalytic materials, graphitic carbon nitride (g-C3N4) shows great promise as a catalytic material for water split-ting, hydrogen generation, and related catalytic applications. Herein, synthesized bulk g-C3N4 is simply irradiated under a 35 fs pulse at mixed photon energies (800 nm and its second harmonic). g-C3N4 was synthesized from melamine following a facile thermal polymerization procedure. The prepared material was introduced, in an aqueous environment, to the
femtosecond laser for various lengths of time. The treated material demonstrates a significant increase in surface area, relative to the untreated samples, indicating that irradiation is a successful method for exfoliation. The subsequent characterization reveals that the mixed irradiation process drives significant defect generation and sheet growth, which is not seen under 800 nm irradiation. Extended
mixed irradiation results in 4 nm thick nanosheets with lateral dimensions 4x that of the bulk material. The treated material shows improved dye absorption/removal. This novel method of defect generation and nanosheet growth shows great potential
as a g-C3N4 pre-treatment method for co-catalytic applications.

Salt-Induced Doping and Templating of Laser-Induced Graphene Supercapacitors

The use of inexpensive and widely available CO₂ lasers to selectively irradiate polymer films and form a graphene foam, termed laser-induced graphene (LIG), has incited significant research attention. The simple and rapid nature of the approach and the high conductivity and porosity of LIG have motivated its widespread application in electrochemical energy storage devices such as batteries and supercapacitors. However, nearly all high-performance LIG-based supercapacitors reported to date are prepared from costly, petroleum-based polyimide (Kapton, PI). Herein, we demonstrate that incorporating microparticles of inexpensive, non-toxic, and widely abundant sodium salts such as NaCl and Na₂SO₄ into poly(furfuryl alcohol) (PFA) resins enables the formation of high-performance LIG. The embedded particles aid in carbonization and act as a template for pore formation. While increasing both the carbon yield and surface area of the electrodes, the salt also dopes the LIG formed with S or Cl. The combination of these effects results in a two- to four-order-of-magnitude increase in device areal capacitance, from 8 μF/cm² for PFA/no salt at 5 mV/s to up to 80 mF/cm² for some PFA/20% Na₂SO₄ samples at 0.05 mA/cm², significantly higher than that of PI-based devices and most other LIG precursors.

Encapsulating a Responsive Hydrogel Core for Void Space Modulation in High-Stability Graphene-Wrapped Silicon Anodes

Due to its formidably high theoretical capacity (3590 mAh/g at room temperature), silicon (Si) is expected to replace graphite as the dominant anode for higher energy density lithium (Li)-ion batteries. However, stability issues stemming from silicon's significant volume expansion (∼300%) upon lithiation have slowed down commercialization. Herein, we report the design of a scalable process to engineer core-shell structures capable of buffering this volume expansion, which utilize a core made up of a poly(ethylene oxide)-carboxymethyl cellulose hydrogel and silicon protected by a crumpled graphene shell. The volume expansion of the hydrogel upon exposure to water creates a void space between the Si-Si and Si-rGO interfaces within the core when the gel dries. Unlike sacrificial spacers, the dehydrated hydrogel remains in the core and acts as an elastic Li-ion conductor, which improves the stability and high rate performance. The optimized composite electrodes retain ∼81.7% of their initial capacity (1055 mAh/(g_rGO+gel+Si)) after 320 cycles when an active material loading of 1 mg/cm² is used. At more practical mass loadings (2.5 mg/cm²), the electrodes achieve 2.04 mAh/cm² and retain 79% of this capacity after 200 cycles against a lithium half-cell. Full cells assembled using a lithium ion phosphate cathode lose only 6.7% of their initial capacity over 100 cycles, demonstrating the potential of this nanocomposite anode for use in next-generation Li-ion batteries.

Controlling Void Space in Crumpled Graphene-Encapsulated Silicon Anodes using Sacrificial Polystyrene Nanoparticles

Silicon anodes have a theoretical capacity of 3590 mAh g^-1 (for Li₁₅ Si₄ , at room temperature), which is tenfold higher than the graphite anodes used in current Li-ion batteries. This, and silicon's natural abundance, makes it one of the most promising materials for next-generation batteries. Encapsulating silicon nanoparticles (Si NPs) in a crumpled graphene shell by spray drying or spray pyrolysis are promising and scalable methods to produce core-shell structures, which buffer the extreme volume change (>300 vol %) caused by (de)lithiaton of silicon. However, capillary forces cause the graphene-based materials to tightly wrap around Si NP clusters, and there is little control over the void space required to further improve cycle life. Herein, a simple strategy is developed to engineer void-space within the core by incorporating varying amounts of similarly sized polystyrene (PS) nanospheres in the spray drier feed mixture. The PS completely decomposes during thermal reduction of the graphene oxide shell and results in Si cores of varying porosity. The best performance is achieved at a 1 : 1 ratio (PS/Si), leading to high capacities of 1638, 1468, and 1179 mAh g^-1 _Si+rGO at 0.1, 1, and 4 A g^-1 , respectively. Moreover, at 1 A g^-1 , the capacity retention is 80.6 % after 200 cycles. At a practical active material loading of 2.4 mg cm^-2 , the electrodes achieve an areal capacity of 2.26 mAh cm^-2 at 1 A g^-1 .

Polymer Binders: Characterization and Development toward Aqueous Electrode Fabrication for Sustainability

Binders play an important role in electrode processing for energy storage systems. While conventional binders often require hazardous and costly organic solvents, there has been increasing development toward greener and less expensive binders, with a focus on those that can be processed in aqueous conditions. Due to their functional groups, many of these aqueous binders offer further beneficial properties, such as higher adhesion to withstand the large volume changes of several high-capacity electrode materials. In this review, we first discuss the roles of binders in the construction of electrodes, particularly for energy storage systems, summarize typical binder characterization techniques, and then highlight the recent advances on aqueous binder systems, aiming to provide a stepping stone for the development of polymer binders with better sustainability and improved functionalities.

Nanoscale assembling of graphene oxide with electrophoretic deposition leads to superior percolation network in Li-ion electrodes: TiNb2O7/rGO composite anodes

In this paper, electrophoretic deposition (EPD) is shown to promote nanoscale assembling of graphene oxide (GO) enabling the fabrication of highly homogeneous, robust, and capacity fade resistant composite titanium niobate (TiNb2O7, TNO)/rGO anodes upon reductive annealing. Control tests revealed that EPD is superior to conventional PVDF-based casting in maximizing the performance benefits from using reduced GO in Li-ion electrode fabrication as is the case of TNO that is plagued with conductivity and capacity fading problems. In this particular study, we show that there is a synergy developed between GO and EPD with the former (1) stabilizing the EPD suspension, (2) acting as a flexible binder net that affords mechanical integrity during the volume expansion of TNO, (3) serving as a conductive filler, and (4) contributing to Li-ion storage via pseudocapacitance. As a consequence, a superior percolation network is developed. Thus while both EPD- and PVDF- built TNO/rGO composite anodes exhibited high initial capacities (∼350 and 318 mA h g-1) at 0.5 C cycling, respectively, their cycling behaviour was quite different with the latter experiencing high internal polarization and extended degradation. Post-mortem PEEM-XANES analysis clearly demonstrated a highly homogeneous mesostructure in the case of the EPD-built TNO/rGO anode vs. a highly segregated and dis-jointed rGO and TNO component clustering in the PVDF-built electrode.

Olive oil and health: summary of the II international conference on olive oil and health consensus report, Jaén and Córdoba (Spain) 2008

Olive oil (OO) is the most representative food of the traditional Mediterranean Diet (MedDiet). Increasing evidence suggests that monounsaturated fatty acids (MUFA) as a nutrient, OO as a food, and the MedDiet as a food pattern are associated with a decreased risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes and hypertension. A MedDiet rich in OO and OO per se has been shown to improve cardiovascular risk factors, such as lipid profiles, blood pressure, postprandial hyperlipidemia, endothelial dysfunction, oxidative stress, and antithrombotic profiles. Some of these beneficial effects can be attributed to the OO minor components. Therefore, the definition of the MedDiet should include OO. Phenolic compounds in OO have shown antioxidant and anti-inflammatory properties, prevent lipoperoxidation, induce favorable changes of lipid profile, improve endothelial function, and disclose antithrombotic properties. Observational studies from Mediterranean cohorts have suggested that dietary MUFA may be protective against age-related cognitive decline and Alzheimer's disease. Recent studies consistently support the concept that the OO-rich MedDiet is compatible with healthier aging and increased longevity. In countries where the population adheres to the MedDiet, such as Spain, Greece and Italy, and OO is the principal source of fat, rates of cancer incidence are lower than in northern European countries. Experimental and human cellular studies have provided new evidence on the potential protective effect of OO on cancer. Furthermore, results of case-control and cohort studies suggest that MUFA intake including OO is associated with a reduction in cancer risk (mainly breast, colorectal and prostate cancers).

High-power ultrasound in olive paste pretreatment. Effect on process yield and virgin olive oil characteristics

The effect of high-power ultrasound on olive paste, on laboratory thermo-mixing operations for virgin olive oil extraction, has been studied. Direct sonication by an ultrasound probe horn (105 W cm(-2) and 24 kHz) and indirect sonication with an ultrasound-cleaning bath (150 W and 25 kHz) were applied and their effects compared with the conventional thermal treatment. A quick-heating of olive paste, from ambient (12-20 degrees C) to optimal temperature conditions (28-30 degrees C), and an oil extractability improvement were observed when applying sonication. Better extractability was obtained by direct sonication for high moisture olives (>50%) whereas indirect sonication gave greater extractability for low moisture olive fruits (<50%). Optimal application of ultrasound was achieved with direct sonication for 4 min at the beginning of paste malaxation and with indirect sonication during the malaxation time. Effect of high-power ultrasound on oil quality parameters and nutritional and sensory characteristics were studied. Changes in quality parameters (free acidity value, peroxide value, K270 and K232) were not found, however significant effects on the levels of bitterness, polyphenols, tocopherols (vitamin E), chlorophyll and carotenoids were observed. Oils from sonicated pastes showed lower bitterness and higher content of tocopherols, chlorophylls and carotenoids. Related to sensory characteristics, off-flavour volatiles were not detected in oils from sonication treatments. Total peak areas of volatiles and the ratio hexanal/E-2-hexenal, as determined by SPME analysis, were lower than non-sonicated reference oils; sensory evaluation by panel test showed higher intensity of positive attributes and lesser of negative characteristics than those untreated.

Low-cholesterol and high-fat diets reduce atherosclerotic lesion development in ApoE-knockout mice

We have investigated the effect of most common oils used in human nutrition on the development of atherosclerosis in apoE-knockout mice. Seven groups of animals, separated according to sex, were fed for 10 weeks either chow diet or the chow diet 10% (wt/wt) enriched with different oils (palm, coconut, 2 types of olive oil, and 2 types of sunflower oil) without addition of cholesterol. At the end of this period, plasma lipid parameters were measured and vascular lesions scored. None of the diets induced changes in plasma cholesterol concentrations, whereas plasma triglycerides were uniformly reduced in all diet groups. Some diets caused significant reductions in the size of atherosclerotic lesions in males and others in females; males responded most to sunflower oils and females to palm oil and one olive oil (II). The lesion reduction in males consuming sunflower oils was associated with the decrease of triglycerides in triglyceride-rich lipoproteins, whereas the decrease in females consuming olive oil II or palm oil was accompanied by an increase in plasma apoA-I. The increase in plasma apoA-I in the latter condition, is mainly due to overexpression of hepatic message elicited by a mechanism independent of apoE ligand. The data suggest that the different diets modulate lesion development in a gender specific manner and by different mechanisms and that the development of atherosclerosis, due to genetic deficiencies, may be modulated by nutritional maneuvers that may be implemented in human nutrition.