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Mass production of defect-free single-layer graphene flakes (SLGFs) by a cost-effective approach is still very challenging. Here, we report such single-layer graphene flakes (SLGFs) (>90%) prepared by a nondestructive, energy-efficient, and easy up-scalable physical approach. These high-quality graphene flakes are attributed to a novel 10 s microwave-modulated solid-state approach, which not only fast exfoliates graphite in air but also self-heals the surface of graphite to remove the impurities. The fabricated high-quality graphene films (∼200 nm) exhibit a sheet resistance of ∼280 Ω/sq without any chemical or physical post-treatment. Furthermore, graphene-incorporated Ni-Fe electrodes represent a remarkable ∼140 mA/cm2 current for the catalytic water oxidation reaction compared with the pristine Ni-Fe electrode (∼10 mA/cm2) and a 120 mV cathodic shift in onset potential under identical experimental conditions, together with a faradic efficiency of >90% for an ideal ratio of H2 and O2 production from water. All these excellent performances are attributed to extremely high conductivity of the defect-free graphene flakes.

Developing easy and effective surface functionalization approaches has required to facilitate the processability of graphene while seeking novel application areas. Herein, an in situ single-step reductive covalent bromination of graphene has been reported for the first time. Highly brominated graphene flakes (>3% Br) were prepared by only subjecting the bromine-intercalated graphite flakes to a reduction reaction with reactive lithium naphthalide. The bromine-functionalized graphene was characterized by X-ray photoelectron spectroscopy and thermogravimetric analysis. Results revealed that Br2 molecules acted as both an intercalating agent for the graphite and a reactant for the surface functionalization of the graphene. After brominating, the remaining negative charges on the reduced graphene surface were further used for the dual surface functionalization of graphene with a long-chain alkyl group (∼1% dodecyl group addition). The functionalized graphenes were also characterized by Fourier transform infrared and Raman spectroscopy.

We investigated the relationship between crystallinity, deep trap states and PEC performance of g-C3N4 photoelectrodes. Long-lived charge carriers were present in the more poorly crystalline samples, due to deeper trap states, which inversely correlated with photoelectrochemical performance. The charge diffusion length in a compact g-C3N4 film was determined to be ca. 1000 nm.

Microwave-promoted continuous flow systems have emerged as a game-changer in nanoparticle synthesis. Owing to the excellent compatibility between fast, sustainable microwave heating and one-step, efficient flow chemistry, this promising technology is meant to enhance the synthetic abilities of nanoscientists. This Perspective aims to present a panoramic view of the state of the art in this field. Additionally, the effect of various microwave and flow parameters on the properties of nanoparticles is discussed along with a comparative glance at the features that make flow reactors more practical and sustainable than their batch counterparts. The overview has also analyzed various microwave continuous flow reactors available in the literature, with an acute emphasis on the nanosynthesis route and design features. Moreover, a discussion on the numerical modeling of microwave flow systems has been made a part of this perspective to reiterate its significance and encourage research in this domain. The Perspective also briefly comments on existing challenges and future prospects of this technology.

The attachment of flexible spacers into aromatic polymers is a molecular design approach that is used for improving processability of aromatic polymers. The concept is attractive because it enables not only the creation of aromatic polymers with improved processability but it is also possible to control phase morphology by simply introducing pendant side chains. Here we report new bisphenol A derivatives bearing alkyl chains of different lengths obtained by an addition reaction can readily make novel poly(arylene sulfone)s with aromatic dihalides and aromatic dioles. They were observed using two-dimension diffusion-ordered spectroscopy nuclear magnetic resonance (2D DOSY NMR) spectra. Attaching flexible alkyl groups into sulfonated poly(arylene sulfone)s allows for increased control of glass transition temperatures, T g , of sulfonated poly(arylene sulfone)s. The alkylated sulfonated poly(arylene sulfone)s had flexibility, increased surface contact angle, improved methanol permeability, and high ion conductivity compared to the neat polymer. Due to the creation of aromatic polymers with improved processability by simply introducing pedant side chains, this novel alkylation method is expected to be applicable to other arylene based proton conductive polymers.

Poly(glycerol sebacate) (PGS) is known as an exciting biomaterial owing to its tunable mechanical properties and controllable degradation rate. However, it is always challenging to control these properties. In this study, we have proposed a solvent-based system to provide a better control of reaction temperature in a microwave cavity, which can minimize evaporation of monomers, and water was collected to analyse the degree of esterification. Pre-PGSs with varied degrees of esterification were prepared using both single mode and multimode microwave cavity irradiation (MI) in this solvent-based reaction system. For a similar degree of esterification of pre-PGSs, the reaction time was almost halved with a better control on mechanical properties by single mode MI compared to multimode MI. Furthermore, the single mode MI approach was compared with the conventional heating (CH) approach. The mechanical properties and degradation rate of PGSs can be controlled readily by using the single mode MI approach compared to CH, which are crucial for their application as a biomaterial. It has been found that the single mode MI not only accelerates the pre-polymerisation process rate by six times, but also speeds up the curing time to the same extent. The Young's modulus of PGSs prepared by single mode MI is increased from 0.77 to 3.14 MPa when the degree of esterification is 66.82%, which is 50% higher than that reported in the literature. Furthermore, PGS using a highly branched pre-PGS prepared by the single mode MI method has a large degree of flexibility. It can achieve a much higher Young's modulus than that obtained by CH with a short curing time (

The dimensional stability and barrier properties of proton exchange membranes are critical issues for high-performance proton exchange membrane fuel cells (PEMFCs). In this work, we introduce a viable and effective strategy for preparing high proton-conductive polymer membranes with remarkable dimensional stability and barrier properties. Sulfonated poly(arylene sulfone)s (sPASs) with a UV-crosslinkable monomer, 2,2′-diallylbisphenol A (DABPA), is successfully synthesized via condensation polymerization, showing competitive molecular weights and sulfonation degrees to the neat polymer. Crosslinked nanocomposite membranes can be fabricated by incorporating soft bridge molecules and exfoliated LAPONITE® nanofillers, and subsequent UV-crosslinking. The sPAS–LAPONITE® nanocomposite membranes show greatly improved dimensional stabilities and barrier properties including remarkably reduced swelling ratio in solvent or methanol aqueous solutions. These enhanced properties lead to excellent performance in a direct methanol fuel cell (DMFC) test, surpassing that of a commercially available Nafion membrane based devices.

Graphitic carbon nitride (g‐C3N4) is a metal‐free semiconductor that has been widely regarded as a promising candidate for sustainable energy production or storage. In recent years, g‐C3N4 has become the center of attention by virtue of its impressive properties, such as being inexpensive, easily fabricable, nontoxic, highly stable, and environment friendly. Herein, the recent research developments related to g‐C3N4 are outlined, which sheds light on its future prospective. Various synthetic methods and their impact on the properties of g‐C3N4 are detailed, along with discussion on frequently used characterization methods. Different approaches for g‐C3N4 surface functionalization, mainly categorized under covalent and noncovalent strategies, are outlined. Moreover, the processing methods of g‐C3N4, such as g‐C3N4‐based thin films, hierarchical, and hybrid structures, are explored. Next, compared with the extensively studied energy‐related applications of the modified g‐C3N4s, relatively less‐examined areas, such as environmental and sensing, are presented. By highlighting the strong potential of these materials and the existing research gaps, new researchers are encouraged to produce functional g‐C3N4‐based materials using diverse surface modification and processing routes.

The development of energy efficient, reproducible, and high throughput approaches to gold nanoparticle (Au-NP) synthesis has gained increasing attention over the past decades due to applications in biomedicine, sensors, and catalysis. In this work, single mode microwave irradiation is for the first time combined with microflow chemistry to fabricate Au-NPs continuously and reproducibly with controllable size in an aqueous solution. The major experimental parameters including microwave power, citrate-to-gold molar ratio ([Cit]/[Au]), and reaction residence time have been investigated systematically. As indicated by TEM, the mean particle width of the synthesized Au-NPs is between 4 and 15 nm with mean aspect ratio between ∼1.4 and 2.2 after only 90 s of microwave irradiation. Furthermore, the Au particle morphology can be manipulated from nanowires to nanoparticles by adjusting the [Cit]/[Au] ratio. HRTEM analysis of the produced Au-NPs and UV–vis spectroscopy suggests a correlation between the red-shifted...

Azobenzene polymers have great potential and impact on fundamental and applied research. However little is known about their thermal stability and degradation behaviours. Herein, nine conjugated main chain azobenzene polymers were synthesized using the nitroamine derivatives of some diphenylene compounds such as 4-amino-4′-nitrobiphenyl 1, 4-amino-4′-nitrobiphenyl ether 2 and 4-amino-4′-nitrobiphenyl sulfide 3, and comonomers triphenylamine A, N-methyldiphenyl amine B and triphenylphosphine C via diazo coupling reaction. These heteroatom containing polymers were characterized by 1H- and 31P-NMR, FTIR, UV–Vis and Raman spectroscopy. The thermal stability and degradation behaviour of these polymers were studied by means of TGA technique. Electronic spectra of the polymers recorded in DMF showed two strong maxima at ca. 280 and 380 nm. They were resistant to heat up to 270 °C and, produced 41-61% char under a nitrogen atmosphere at 800 °C. UL 94 burning tests performed for TPU Ravathane® (TPE-U) with added azobenzene polymer revealed that these polymers could be used as an intumescent reactive flame retardant additive, particularly for polyurethanes and elastomers, due to their high char yield at relatively high temperatures (e.g 800 °C). The carbonized materials were further characterized by XRD and SEM/EDX.

Many studies have been conducted on organic and inorganic synthesis by microwave heating owing to its special heating mechanism, leading to improved reaction rate, higher purity and yields. We specifically demonstrated microwave heating in the fabrication of nanoparticles and polyester. By fine-tuning the microwave and experimental parameters, the materials prepared have shown excellent physical and bio-properties, e. g. narrow particle size distribution, controlled morphology, varied molecular structure and so forth. We further highlight the recent procedure of using fluidic reactors on preparing both metals and metal oxides nanoparticles. The experimental design strategies and fundamentals of the microwave interaction with chemicals are presented. Furthermore, the key factors and issues facing in this area are also discussed.

Carbon nanotubes (CNTs) are ideal support materials for platinum in fuel cells. However, little is known about the conduction mechanism of Pt-coordinated CNTs. Herein, a coordination complex of pyridine-functionalized single-walled nanotubes (Py-SWNTs) with Pt (Pt/Py-SWNTs) was prepared via the ligand exchange reaction between cis-[Pt(dmso)2Cl2] and Py-SWNTs generated by pyridine diazonium salt addition to SWNTs. The presence of Pt in modified SWNTs was confirmed by X-ray photoelectron spectroscopy (XPS). The N 1s XPS spectra provided evidence of Pt coordination to the pyridine nitrogen atom. Modified SWNTs were further characterized by thermogravimetric analysis coupled with mass spectrometry, ultraviolet-visible-near infrared spectroscopy, Raman spectroscopy, and elemental analysis. The electron conduction mechanism of Pt/Py-SWNT films was best described by a modified quantum tunneling model, identified from a combined analysis of the voltage and temperature dependence of the current.

Covalently interconnected single walled carbon nanotube (SWNT) networks have attracted a particular interest due to their enhanced accessible surface area. Herein, an elegant way of preparing covalently interconnected SWNTs is demonstrated for the first time via coupling reactions. Sonogashira and Ullmann coupling reactions offer a versatile route for the preparation of molecularly-bridged SWNTs (MBSWNTs). Couplings create C C bonds between SWNTs yielding MBSWNTs with conductive 1,2-diphenyl-diacetylene and biaryl bridges. Elemental composition analysis done by XPS shows the evidence of successful couplings while mass traces of the interconnected SWNTs corroborating with fragmentations corresponding to conjugated linkers.

The bandgap engineering of semiconductors, in particular low‐cost organic/polymeric photocatalysts could directly influence their behavior in visible photon harvesting. However, an effective and rational pathway to stepwise change of the bandgap of an organic/polymeric photocatalyst is still very challenging. An efficient strategy is demonstrated to tailor the bandgap from 2.7 eV to 1.9 eV of organic photocatalysts by carefully manipulating the linker/terminal atoms in the chains via innovatively designed polymerization. These polymers work in a stable and efficient manner for both H2 and O2 evolution at ambient conditions (420 nm < λ < 710 nm), exhibiting up to 18 times higher hydrogen evolution rate (HER) than a reference photocatalyst g‐C3N4 and leading to high apparent quantum yields (AQYs) of 8.6%/2.5% at 420/500 nm, respectively. For the oxygen evolution rate (OER), the optimal polymer shows 19 times higher activity compared to g‐C3N4 with excellent AQYs of 4.3%/1.0% at 420/500 nm. Both theoretical modeling and spectroscopic results indicate that such remarkable enhancement is due to the increased light harvesting and improved charge separation. This strategy thus paves a novel avenue to fabricate highly efficient organic/polymeric photocatalysts with precisely tunable operation windows and enhanced charge separation.

WOS:000268898300082 The preparation of new poly(urethane-imide)s (PUIs) having acceptable thermal stability and higher flame resistance was aimed. Two new aromatic diisocyanate-containing methyldiphenylphosphine oxide and triphenylphosphine oxide moieties were synthesized via Curtius rearrangement in situ and polymerized by various prepared diols. Four aliphatic hydroxy terminated aromatic based diols were synthesized by the reaction between ethylene carbonate and various diphenolic Substances. Chemical structures of monomers and polymers were characterized by FTIR, (1)H NMR, (13)C NMR, and (31)P NMR spectroscopy. Thermal stabilities and decomposition behaviors of the PUIs were tested by DSC and TGA. Thermal measurements indicate that the polymers have high thermal stability and produce high char. Polymers exhibit quite high fire resistance, evaluated by fire test UL-94. The films of the polymers were prepared by casting the solution. Inherent viscosities, solubilities, and water absorbtion behaviors of the polymers were reported in. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114:1329-1338, 2009

Gold nanoparticles (AuNPs) can be evenly deposited on single-walled carbon nanotubes (SWCNTs) via the reduction of the highly stable complex, chloro(triphenylphosphine) gold(I), with SWCNT anions ('nanotubides'). This methodology highlights the unusual chemistry of nanotubides and provides a blueprint for the generation of many other hybrid nanomaterials.

Sonicating pure N-methyl pyrrolidone (NMP) rapidly produces contaminating organic nanoparticles, at increasing concentration with time, as investigated by AFM, as well as UV-vis, IR and NMR spectroscopies. The contamination issue affects carbon nanotube, and likely other nanomaterial, dispersions processed by sonication in organic solvents.