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•Electrocatalyst CFO based bipolar ANF hybrid membrane were designed.•CFOANFcan accomplish raid adsorption and conversionof lifhium polysulides.•CFOANF exhibits excellent ...electrochemical performances under high sulfur loading.
Lithium-sulfur battery have been considered as promising energy storage devices because of its superiority in energy density. However, the low active material utilization, low sulfur loading, shuttle effect and torpid kinetics of polysulfides, and poor cycling stability limit its commercial applications. Herein, the functionalized nitrogen doped carbon nanofibers containing amide groups were designed by electrospun and polyamidoamine dendrimer (PAMAM) solution impregnation techniques. The obtained amide groups modified nitrogen-doped carbon nanofibers (ANF) were combined with spinel CoFe2O4 (CFO) nanoparticles (CFOANF) via hydrothermal method to design as membrane electrode containing Li2S6 catholyte for lithium-sulfur batteries. The introduction of nitrogen doped and amide groups modified ANF can increase fibers polarity, which have chemical adsorption capability toward lithium polysulfides. CFO nanoparticles can further absorb the soluble polysulfides by strong chemical interaction due to its intrinsic polarity and also serve as a catalyst to promote the redox kinetics of polysulfides conversion. Benefiting from the synergism of the physical confinement, polar chemical adsorption, and catalytic conversion, the as-prepared CFOANF delivers excellent electrochemical performances at high sulfur loading. The as-prepared CFOANF membrane with 6.3 mg cm−2 sulfur loading delivers a high initial capacity of 940 mAh g−1 and excellent long-term cycling stability up to 450 cycles with a low decay rate 0.059 % per cycle at 0.2C. Remarkably, even at 12.6 mg cm−2 and 16.4 mg cm−2 sulfur loading, the CFOANF membrane electrodes show high capacity of 9.7 mAh cm−2 and 11.8 mAh cm−2, respectively. The results show that the chemically anchoring polysulfides and catalyzing redox reaction by multifunctional CFOANF hybrid composite is promising for assembling with a high sulfur loading electrode, which exhibits a superior electrochemical performance in lithium-sulfur batteries.
•Carbon material amidation is presented for sodium-ion battery electrodes.•Amide group renders anode enlarged interlayer distances and active sites.•Symmetric sodium-ion battery has high energy and ...power density.•The strategy features low cost, scale production, and environmental friendliness.
Structure design of carbon materials, like the heteroatom doping, is one of the effective strategies to develop high-performance anode of sodium-ion battery (SIB). However, challenges remain in sodium ion storage capacity, rate capability and cycle life. Here, an amidation structure design strategy is rationally proposed, and the regulated electrode exhibits not only remarkable electrochemical performance, but also great potential in scale commercial production. Mesocarbon microbead (MCMB), a graphitic spherical particle with excellent physiochemical properties but low-cost production process, is applied to the amidation process, achieving enlarged interlayer distances up to ∼ 0.42 nm and rich –CONH2 active sites. The amidated MCMB (MCMBO-NH2) anode displays a high specific capacity of 220 mAh/g, with a retention rate of about 83.6 % after 500 cycles. The MCMBO-NH2 cathode remains stable at the specific capacity of 141 mAh/g after 250 cycles. The symmetric sodium-ion full cell then demonstrates a high energy density of 145 Wh/kg at a large power density of 12,500 W/kg, and an excellent capacity retention rate of 96.1% after 500 cycles, which is superior to the previous work of the symmetric SIBs. The amidation design of carbon materials comes with outstanding battery performance and cost-effective production process, offering a significant commercial value for the industrialization of SIBs.
A polyamide compound was grafted to GO nanosheets and functions as “spacer” and nitrogen source for the synthesis of N-3DMG.
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•N-3DMG is facilely synthesized and used as high ...performance electrode materials.•Polyamide can inhibit the restacking of G and serve as the N source of N-3DMG.•N-3DMG exhibits excellent specific capacitance and excellent cyclic stability.•The capacitance of N-3DMG is better than most other carbon based materials.
3D N-doped mesoporous graphene (N-3DMG) is fabricated by using amidated graphene oxide (AMGO) as the precursor. The amidation of graphene oxide not only avoids restacking of graphene sheets when AMGO is reduced to amidated graphene (AMG), but also provides nitrogen source for the N-3DMG. When the N-3DMG is used for supercapacitor, it exhibits a considerable specific capacitance, high rate capability and excellent cyclic stability. The 3D mesoporous structure and the high N-doping content are believed to be responsible for the high capacitive performances.
Herein, we report the copper-catalyzed dehydrogenative C(sp2)–N bond formation of 4-pentenamides via nitrogen-centered radicals. This reaction provides a straightforward and efficient preparation ...method for γ-alkylidene-γ-lactams. Notably, we could controllably synthesize α,β-unsaturated- or α,β-saturated-γ-alkylidene-γ-lactams depending on the reaction conditions.
Amidation crosslinking polymeric carbon nitride enables the electron with faster mobility thus realizing a high photocatalytic H2O2 production performance.
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•Three kinds of amidation ...crosslinking polymeric carbon nitride (g-C3N4) were constructed.•A higher photocatalytic H2O2 production were realized over modified g-C3N4.•The modified g-C3N4 show faster and easier transport of charge carriers.•This work is well enlightening for the synthesis of modified g-C3N4 materials.
Hydrogen peroxide (H2O2) has been widely used as eco-friendly oxidant in many chemical industries and environmental areas. Photocatalytic H2O2 production based on polymeric carbon nitride (g-C3N4) materials is a burgeoning research direction. The primary and secondary amine groups in g-C3N4 framework are considered to be the adverse reaction active sites during photocatalytic H2O2 generation process. Besides, these amine groups can easily form hydrogen bonds with each other which will weaken the separation and transfer of photogenerated carriers in the basal plane of g-C3N4, thus greatly restricts the H2O2 production efficiency. Here, three organic molecules (acetyl chloride, oxalyl chloride and trimesoyl chloride) were successfully covalently introduced into the g-C3N4 through an amide bond synthesis method between amine group and acyl chloride group (ac-g-C3N4-n, oc-g-C3N4-n and tc-g-C3N4-n). All three composites show an enhanced performance toward photocatalytic hydrogen peroxide production compared with pristine g-C3N4. The highest reaction activity reaches 3.2 mmol L−1 in 6 h, which is 3-fold than that of the pristine g-C3N4. This study provides a novelty approach to modify g-C3N4 that focuses on the properties of the semiconductor itself and in-depth insight into the modulation of in-plane electrical conductivity at molecular scale.
A practical and efficient method for the construction of poly substituted oxazoles has been developed using a catalytic amount of potassium iodide and TBHP as the green oxidant via amidation followed ...by intramolecular oxidative cyclization of enaminone derivatives under mild reaction conditions. The attracting feature is oxidation of benzylic C–H bond and dehydrogenation of enaminone occurred in one pot under base free conditions.
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C7−H‐functionalized indoles are ubiquitous structural units of biological and pharmaceutical compounds for numerous antiviral agents against SARS‐CoV or HIV‐1. Thus, achieving site‐selective ...functionalizations of the C7−H position of indoles, while discriminating among other bonds, is in high demand. Herein, we disclose site‐selective C7−H activations of indoles by ruthenium(II) biscarboxylate catalysis under mild conditions. Base‐assisted internal electrophilic‐type substitution C−H ruthenation by weak O‐coordination enabled the C7−H functionalization of indoles and offered a broad scope, including C−N and C−C bond formation. The versatile ruthenium‐catalyzed C7−H activations were characterized by gram‐scale syntheses and the traceless removal of the directing group, thus providing easy access to pharmaceutically relevant scaffolds. Detailed mechanistic studies through spectroscopic and spectrometric analyses shed light on the unique nature of the robust ruthenium catalysis for the functionalization of the C7−H position of indoles.
Lucky seven: The challenging C7−H activation of indoles has been accomplished by ruthenium(II) catalysis. The versatile ruthenium catalysis allowed C−N andC−C bond formation, scalable reactions, and the traceless removal of the directing group. Detailed mechanistic investigations based on diverse analysis tools shed light on a novel mode of action.
The epimerization-free formation of peptide bonds is crucial for the development of peptide therapeutics and pharmaceuticals. Herein, we report a hydrosilane-mediated approach for the construction of ...peptide bonds between most amino acids under ambient conditions. This concise protocol with an original silylating reagent HSi(OCH(CF3)2)3 facilitates the use of amino acids bearing a broad variety of functional groups without any epimerization. Moreover, a catalytic system using an aminosilane catalyst enables not only the acceleration in silylation of carboxylic acids but also amide synthesis with minimal substrate use (electrophile/nucleophile/silylating reagent = 1:1:1) and waste production (hydrogen gas and a siloxane). These simple and powerful approaches are established as a potentially general paradigm in synthesis of desired peptides in high yields.
Here we report the preparation of primary α‐ketoamides via a highly efficient molecular iodine‐mediated oxidative amidation of aryl methyl ketones with ammonium carbamodithioate. A self‐sequenced ...iodination/nucleophilic substitution/Kornblum oxidation/amidation mechanism was proposed. In this mechanism, α‐thiocyanatoacetophenone is the key intermediate.
An I2‐mediated oxidative amidation leads to a wide variety of primary α‐ketoamides from aryl methyl ketones with ammonium carbamodithioate is described. Control experiments indicated an iodination/nucleophilic substitution/Kornblum oxidation/amidation mechanism.
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