Most bulk-scale graphene is produced by a top-down approach, exfoliating graphite, which often requires large amounts of solvent with high-energy mixing, shearing, sonication or electrochemical ...treatment
. Although chemical oxidation of graphite to graphene oxide promotes exfoliation, it requires harsh oxidants and leaves the graphene with a defective perforated structure after the subsequent reduction step
. Bottom-up synthesis of high-quality graphene is often restricted to ultrasmall amounts if performed by chemical vapour deposition or advanced synthetic organic methods, or it provides a defect-ridden structure if carried out in bulk solution
. Here we show that flash Joule heating of inexpensive carbon sources-such as coal, petroleum coke, biochar, carbon black, discarded food, rubber tyres and mixed plastic waste-can afford gram-scale quantities of graphene in less than one second. The product, named flash graphene (FG) after the process used to produce it, shows turbostratic arrangement (that is, little order) between the stacked graphene layers. FG synthesis uses no furnace and no solvents or reactive gases. Yields depend on the carbon content of the source; when using a high-carbon source, such as carbon black, anthracitic coal or calcined coke, yields can range from 80 to 90 per cent with carbon purity greater than 99 per cent. No purification steps are necessary. Raman spectroscopy analysis shows a low-intensity or absent D band for FG, indicating that FG has among the lowest defect concentrations reported so far for graphene, and confirms the turbostratic stacking of FG, which is clearly distinguished from turbostratic graphite. The disordered orientation of FG layers facilitates its rapid exfoliation upon mixing during composite formation. The electric energy cost for FG synthesis is only about 7.2 kilojoules per gram, which could render FG suitable for use in bulk composites of plastic, metals, plywood, concrete and other building materials.
An efficient metal‐free catalyst is presented for oxygen evolution and reduction based on oxidized laser‐induced graphene (LIG‐O). The oxidation of LIG by O2 plasma to form LIG‐O boosts its ...performance in the oxygen evolution reaction (OER), exhibiting a low onset potential of 260 mV with a low Tafel slope of 49 mV dec−1, as well as an increased activity for the oxygen reduction reaction. Additionally, LIG‐O shows unexpectedly high activity in catalyzing Li2O2 decomposition in Li‐O2 batteries. The overpotential upon charging is decreased from 1.01 V in LIG to 0.63 V in LIG‐O. The oxygen‐containing groups make essential contributions, not only by providing the active sites, but also by facilitating the adsorption of OER intermediates and lowering the activation energy.
The oxidation of laser‐induced graphene (LIG) by O2 plasma to form oxidized LIG boosts its performance in both the oxygen evolution reaction (OER) and the oxygen reduction reaction. The oxygen‐containing groups make essential contributions, not only by providing the active sites, but also by facilitating the adsorption of oxygen evolution reaction (OER) intermediates and lowering the activation energy.
Facile design of low‐cost and high‐efficiency catalysts with earth‐abundant and cheap materials is desirable to replace platinum (Pt) for the hydrogen evolution reaction (HER) in water splitting, but ...the development of such HER catalysts with Pt‐like activity using simple strategies remains challenging. A mesoporous hybrid catalyst of nickel phosphides nanoparticles and cobalt phosphosulfide/phosphide (CoS|Ni|P) nanosheet arrays for HER is reported here, which is developed by a facile three‐step approach consisting of electrodeposition, thermal sulfurization, and phosphorization. This hybrid catalyst is highly robust and stable in acid for HER, and is distinguished by very low overpotentials of 41, 88, and 150 mV to achieve 10, 100, and 1000 mA cm−2, respectively, as well as a small Tafel slope (45.2 mV dec−1), and a large exchange current density (964 µA cm−2). It is among the most efficient earth‐abundant catalysts reported thus far for HER. More importantly, this electrocatalyst has electrochemical durability over 20 h under a wide range of current densities (up to 1 A cm−2) in acidic conditions, as well as very high turnover frequencies of 0.40 and 1.26 H2 s−1 at overpotentials of 75 and 100 mV, respectively, showing that it has great potential for practical applications in large‐scale water electrolysis.
A highly active and durable hydrogen‐evolving electrocatalyst, which requires a very low overpotential of 41 mV to achieve 10 mA cm−2, and has a very large turnover frequency of 1.26 H2 s−1 at 100 mV overpotential, is developed by in situ growing nickel phosphide nanoparticles on 3D cobalt phosphosulfide/phosphide nanosheet arrays.
Nanoparticles have shown promise as both drug delivery vehicles and direct antitumor systems, but they must be properly designed in order to maximize efficacy. Computational modeling is often used ...both to design new nanoparticles and to better understand existing ones. Modeled processes include the release of drugs at the tumor site and the physical interaction between the nanoparticle and cancer cells. In this paper, we provide an overview of three different targeted drug delivery methods (passive targeting, active targeting, and physical targeting) and compare methods of action, advantages, limitations, and the current stages of research. For the most commonly used nanoparticle carriers, fabrication methods are also reviewed. This is followed by a review of computational simulations and models on nanoparticle-based drug delivery.
Sustainable, inexpensive, and environmentally friendly biomass waste can be exploited for large‐scale production of carbon nanomaterials. Here, alkali lignin was employed as a precursor to synthesize ...carbon quantum dots (CQDs) with bright green fluorescence through a simple one‐pot route. The prepared CQDs had a size of 1.5–3.5 nm, were water‐dispersible, and showed wonderful biocompatibility, in addition to their excellent photoluminescence and electrocatalysis properties. These high‐quality CQDs could be used in a wide range of applications such as metal‐ion detection, cell imaging, and electrocatalysis. The wide range of biomass lignin feedstocks provide a green, low‐cost, and viable strategy for producing high‐quality fluorescent CQDs and enable the conversion of biomass waste into high‐value products that promote sustainable development of the economy and human society.
Go green: Sustainable, inexpensive, and environmentally friendly biomass waste alkali lignin is employed as a precursor to synthesize carbon quantum dots (CQDs) with bright green fluorescence through a simple one‐pot route. The prepared CQDs have a size of 1.5–3.5 nm, are water‐dispersible, and have wonderful biocompatibility, in addition to their excellent photoluminescence and electrocatalysis properties.
We present here a straightforward synthesis of highly efficient bifunctional OER/ORR catalysts through a facile laser-induced graphene (LIG) process to produce Co3O4/LIG. The Co3O4/LIG showed OER and ...ORR activity comparable to noble metal-based catalysts in alkaline electrolyte. Furthermore, the Co3O4/LIG exhibited promising performance in Zn-air and Li-O2 batteries. The rechargeable Zn-air battery has an open-circuit potential of 1.46 V and a high power density of 84.2 mW/cm2 at 100 mA/cm2. The Li-O2 battery with the Co3O4/LIG cathode exhibits low overpotentials in both charge and discharge processes and excellent cycling stability up to 242 cycles.
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Electronic metal‐support interactions (EMSIs) of oxide‐supported metal catalysts strongly modifies the electronic structures of the supported metal nanoparticles. The strong influence of EMSIs on the ...electronic structures of oxide overlayers on metal nanoparticles employing cerium oxides/Ag inverse catalysts is reported herein. Ce2O3 overlayers were observed to exclusively form on Ag nanocrystals at low cerium loadings and be resistant to oxidation treatments up to 250 °C, whereas CeO2 overlayers gradually developed as the cerium loading increased. Ag cubes enclosed by {001} facets with a smaller work function exert a stronger EMSI effect on the CeOx overlayers than Ag cubes enclosed by {111} facets. Only the CeO2 overlayers with a fully developed bulk CeO2 electronic structure significantly promote the catalytic activity of Ag nanocrystals in CO oxidation, whereas cerium oxide overlayers with other electronic structures do not. These results successfully extend the concept of EMSIs from oxide‐supported metal catalysts to metal‐supported oxide catalysts.
Electronic metal‐support interactions (EMSIs) occur in CeOx/Ag inverse catalysts via charge transfer from Ag to CeOx. Ag cubes enclosed by {001} facets with a smaller work function exert a stronger EMSI effect than Ag cubes enclosed by {111} facets. The EMSIs strongly affect the electronic structures and catalytic activity of the CeOx overlayers on the Ag nanocrystals in CeOx/Ag inverse catalysts.
Invited for the cover of this issue is Weixin Huang and co‐workers at the University of Science and Technology of China. The image depicts the strong influence of electronic metal‐support interaction ...(EMSI) on electronic structures and the catalytic activity of CeOx
/Ag inverse catalysts. Read the full text of the article at 10.1002/chem.201904134.
“We want to demonstrate that the electronic metal‐support interaction occurring in oxide/metal inverse catalysts can be tuned by the exposed facets of metal substrates.” Read more about the story behind the cover in the Cover Profile and about the research itself on page 15978 ff. (DOI: 10.1002/chem.201904134).
The development of a rechargeable Li metal anode (LMA) is an important milestone for improved battery technology. Practical issues hindering LMAs are the formation of Li dendrites and inactive Li ...during plating and stripping processes, which can cause short circuits, thermal runaway, and low coulombic efficiency (CE). Here, the use of a laser‐induced silicon oxide (LI‐SiOx) layer derived from a commercial adhesive tape to improve the reversibility of Li metal batteries (LMBs) is studied. The silicone‐based adhesive of the tape is converted by a commercial infrared laser into a homogeneous porous SiOx layer deposited directly over the current collector. The coating results in superior performance by suppressing the formation of Li dendrites and inactive Li and presenting higher average CE of 99.3% (2.0 mAh cm−2 at 2.0 mA cm−2) compared to bare electrodes. The thickness and morphology of the deposited Li is investigated, revealing a different mechanism of Li deposition on coated electrodes. The laser coating affords a method that is fast and avoids the use of toxic organic solvents and extensive drying times. The improved performance with the SiOx coating is demonstrated in LMB with a zero‐excess (“anode‐free”) configuration where a 100% improved performance is verified.
A laser‐induced silicon oxide (LI‐SiOx) layer derived from a commercial adhesive tape can improve the reversibility of Li metal batteries. The coating results in superior performance by suppressing the formation of Li dendrites and presenting higher average coulombic efficiency of 99.3% (2.0 mAh cm−2 at 2.0 mA cm−2) and improved cycle life compared to the electrode without a SiOx coating.
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