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Lithium sulfur battery is one of the most promising applicants for the next generation of energy storage devices whose commercial applications are impeded by the key issue of shuttle effect. To overcome this obstacle, various of two-dimensional (2D) carbon-based metal-free compounds have been proposed to serve as anchoring materials for immobilizing soluble lithium polysulfides (LiPs), which however suffered from low electronic conductivity implying unsatisfactory performance for catalyzing sulfur redox. Therefore, we predicted metallic C5N monolayers, possessing hexagonal (H) and orthorhombic (O) phases, which exhibit excellent performances for suppressing the shuttle effect. First principles simulations demonstrate that O-C5N could serve as bifunctional anchoring material due to its strong adsorption capability to LiPs and excellent catalytic performance for sulfur redox with active sites from both basal plane and zigzag edges. Furthermore, the rate of Li2S oxidation over O-C5N is fast due to low energy barrier of 0.93eV for Li2S decomposition. While for H-C5N only N atoms locating at the armchair edges can efficiently trap LiPs and boost the formation and dissociation of Li2S during discharge and charge processes, respectively. The current work opens an avenue of designing 2D metallic carbon-based anchoring materials for Lithium sulfur battery, which deserves further experimental research efforts.

An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered.

A facile and efficient oxidative functionalization of vinyl azides with aldehydes furnishing a diverse array of β-acylated enaminones was developed.

An efficient and eco-friendly approach for highly diastereoselective synthesis of spirocycloalkane fused pyrazolo[3,4-b]pyridine derivatives has been developed. The one-pot three-component reaction enables multiple bond-forming events including C–C and C–N bonds under mild conditions using easily available starting materials, leading to diastereoselective generation of N-containing spirocycles. The advantages of inexpensive and easily available starting materials, green and mild reaction conditions, recyclable and easily separable heterogeneous catalysts, broad substrate scope and simple one-pot operation make this strategy highly attractive.

A multicomponent two-step strategy for the synthesis of polysubstituted pyrrolo[3,2-c]pyridin-4-one derivatives has been described. The reactions can be readily performed by mixing inexpensive starting materials using two-step methods under mild conditions, and the products can be easily obtained from the mother liquid without any further treatment. Moreover, the solid acid catalyst can be circulated at least 6 times without obvious deactivation. Furthermore, a mechanism for the reaction process has been proposed. Overall the bond forming efficiency, the use of green solvent as the reaction medium, recyclability of the solid acid catalyst, easy work-up/purification, and a wide substrate scope make this method highly attractive to assemble heterocyclic scaffolds.

2D hybrid solid superacids with extremely high acid strength and outstanding mass transfer properties were prepared and exhibit superior activities for biomass conversion., Solid acids have been widely used as heterogeneous catalysts in developing green and sustainable chemistry. However, it remains a challenge to improve the mass transport properties and acid strength of solid acids simultaneously. Herein, we report a class of two dimensional (2D) layered hybrid solid acids with outstanding mass transfer and extremely high acid strength by incorporating sulfonated polymers in-between montmorillonite layers. The 2D layered structure and broad distribution of pore sizes allow for highly efficient mass transport of substrate molecules into and out of the solid acids. The acid strength of these solid acids was found to be stronger than that of 100% H2SO4, H3PW12O40 and any other reported solid acids to date, as determined by 1H and 31P solid-state NMR. These 2D solid acids show extraordinary catalytic performance in biomass conversion to fuels, superior to that of H3PW12O40, HCl and H2SO4. Theoretical calculations and control experiments reveal that H-bond based interactions between the polymer and montmorillonite facilitate the unusually high acid strengths found in these samples.

Chitosan composite superfine fibers with a diameter of 321 ± 99 nm were prepared by electrospinning with PEO as the co-spinning polymer and itaconic acid as the in situ cross-linking agent. Itaconic acid was homogeneously dispersed in chitosan fibers and the in situ cross-linking endowed the prepared chitosan composite fibers with improved solvent resistance, thermostability and mechanical strength. Palladium species immobilized on these annealed chitosan fibers can efficiently catalyze the reduction reaction of 4-nitrophenol as well as the Mizoroki–Heck reaction of aromatic iodides with n-butyl acrylate in an aqueous medium. Furthermore, the larger fiber structure can facilitate the recovery and reuse of the palladium catalyst. The remarkable catalytic performance and easy recovery make this novel fiber-supported palladium catalyst hold great potential applications in green chemistry.

The Pd(TFA)2-catalyzed denitrogenative addition proceeded with selective C–N bond cleavage of arylhydrazines with nitriles in the presence of DABCO and HFBA under air at room temperature. Aryl ketones could be easily synthesized via the hydrolysis of the ketimine moiety generated in situ without the need for additional water.

Chitosan microspheres-supported palladium catalysts (Pd@CM) for Mizoroki–Heck reaction have been successfully prepared by electrospraying PdCl2/chitosan mixture in a trifluoroacetic acid (TFA) aqueous solution. Swelling capacity measurement and thermal analysis demonstrated that the palladium species in the chitosan microspheres could cross-link the chitosan efficiently. FT-IR spectra demonstrated that the chitosan in the microspheres could be cross-linked by glutaraldehyde, and the formed Schiff bond could chelate the palladium species efficiently. High resolution transmission electron microscopy (HR-TEM) indicated that the entrapment of palladium species in chitosan microspheres could enhance its dispersion. Mizoroki–Heck reaction catalysis results demonstrated that the catalytic activity of Pd@CM was associated with the size of chitosan microspheres. The Pd@CM with a suitable size was even more active than the catalyst with palladium species adsorbed on the surface of chitosan microspheres (Pd-CM). Moreover, the entrapment of palladium species in chitosan microspheres could reduce its aggregation and leaching in the catalysis procedure, which in turn increased the reusability of Pd@CM catalyst. The high catalytic activity and stability of Pd@CM have been attributed to the entrapment of palladium species within the cross-linked chitosan microspheres and the chelation of palladium species with the abundant amine and hydroxyl groups on chitosan chain.

Micro–meso–macroporous polymers (MOPs) grafted with versatile functional groups, such as sulfonate, amine, triazole, pyridine, strong acidic ionic liquids and triphenylphosphine, were synthesized by in situ cross-linking of different functional molecules with 1,4-bis(chloromethyl)benzene in the presence of Lewis acid catalysts without using additional templates. The resultant hyper-cross-linked nanoporous polymers show unique characteristics such as large BET surface areas (up to 1523 m2 g−1), abundant micro–meso–macropores (4.5–131 nm), and tunable and versatile active sites (acid, base and palladium). These functional polymers exhibit excellent activities and good reusability in biomass conversions, cross-coupling reactions and condensation. The catalytic activities are much better than those of various conventional catalysts such as H3PW12O40, SBA-15-SO3H, Amberlyst 15, and mesoporous H-ZSM-5 Pd/C and even as comparable as those of homogeneous H2SO4 and HCl in the depolymerization of crystalline cellulose into fine chemicals and towards transesterification to biodiesel. This work highlights a low cost route to the synthesis of solid catalysts based on functional nanoporous polymers for catalyzing the production of clean biofuels and fine chemicals.

N rich porous carbon based solid acids (NPC-[CxN][X]) have been successfully synthesized by treatment of N rich porous carbon (NPC) with various quaternary ammoniation reagents such as iodomethane, 1,3-propane sultone, and 1,4-butanesultone, and ion exchange with various strong acids such as HSO3CF3, H2SO4, H3PW12O40, HBF4etc. The NPC support was synthesized by carbonization of KOH-activated polypyrrole without using additional templates. Various characterizations showed that NPC-[CxN][X] possesses abundant nanopores, large Brunauer–Emmett–Teller surface areas, good stability, and strong and controllable acid sites with Bronsted characteristics. The immobilized acidic groups were homogeneously dispersed into NPC-[CxN][X]. Notably, NPC-[CxN][X] acted as efficient, reusable and generalized solid acids, which showed excellent activity in various acid-catalyzed reactions such as esterification and transesterification in the synthesis of biodiesel, dehydration of fructose into 5-hydroxymethylfurfural, depolymerization of crystalline cellulose into sugars, and condensation of phenol with acetone in the synthesis of bisphenol A, much higher than that of various solid acids such as Amberlyst 15, H-ZSM-5, H-USY, and sulfonic group functionalized ordered mesoporous silicas. The preparation of NPC-[CxN][X] leads to the development of porous carbon based solid acids with controllable structural characteristics and excellent catalytic activity.

The objective of this study was to develop novel chitosan-based/montmorillonite/palladium (CS/MMT/Pd) hybrid microsphere catalysts with improved properties for use in Sonogashira reactions. Interactions between a chitosan matrix and a montmorillonite nanofiller were revealed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric (TG) analysis. The results confirmed the formation of the intercalation structure between CS macromolecules and MMT layers. X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HR-TEM) analysis results showed that the Pd species of different valencies were dispersed at the nano-level in both the CS matrix and the interlayers of MMT. CS/MMT/Pd hybrid microspheres were highly active for the Sonogashira reactions of aryl iodides and alkynes at a palladium catalyst loading of 0.3 mol%. They can be recycled 10 times without a significant decrease in coupling yields. It was concluded that introducing MMT into the CS matrix will effectively improve the thermal stability and Pd leaching-resistance of the hybrid microsphere catalysts. The results in this study demonstrated the great potential of such heterogeneous catalysts applied in Sonogashira reactions.

Strong acid ionic liquids and sulfonic group bifunctional graphene-like nanoporous carbons (GNC-SO3H-ILs) have been synthesized by treating nitrogen containing graphene-like nanoporous carbons (GNCs) with 1,3-propanesultone, ion exchanging with HSO3CF3 or H2SO4. Introducing nitrogen is important for grafting strong acid ionic liquids and sulfonic group in GNCs, which were synthesized from carbonization of a mixture of dicyandiamide or melamine and glucose. GNC-SO3H-ILs possess abundant nanopores, nanosheet structure, good dispersion and controlled acidity. By themselves, they are capable of enhancing the fast diffusion of reactants and products, while increasing the exposure degree of acidic sites in GNC-SO3H-ILs throughout various reactions. The above characteristics resulted in their much improved catalytic activity in biomass transformations such as the production of biodiesel and depolymerization of crystalline cellulose into sugars, which was even comparable to those of homogeneous ionic liquid and mineral acids.

A one-step synthesis of a large-area and highly nitrogen-doped graphene (NG) membrane with few defects derived from poly 4-vinyl pyridine (P4VP) has been reported. The synthesis temperature has been optimized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). With this approach, a large-area of more than 80% single-layer NG membrane with a nitrogen content of 6.37% can be obtained. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman mapping-mode, optical microscopy (OM) and transmission electron microscopy (TEM) analyses reveal that the resultant NG is a flat, continuous, uniform and monolayered graphene membrane with a large area and a well-ordered crystalline structure. The electrical measurement confirms the typical n-type field-effect transistors (FETs) for NG both in air and vacuum, and the electron mobility can reach as high as 365 cm2 V−1 s−1, much higher than those of NGs previously reported. In addition, the transmittance and sheet resistance of NG correlates well with a monolayered structure and semiconducting properties, which also makes it a candidate of transparent electrode for various optoelectronic devices.

Palladium (Pd)-catalyzed desulfitative cross-coupling reactions of sodium arylsulfinates with a wide variety of arylboronic acids were achieved in good to excellent yields under simple aerobic conditions. These catalytic reactions could be accelerated by addition of a catalytic amount of Cu(II) salts as co-catalyst. Moreover, these reactions were tolerant to all of the tested functional groups, making them attractive alternatives to the traditional cross-coupling reactions.

The silver-catalyzed coupling of arylboronic acids with arylglyoxylic acids was found to be an extremely efficient route for the synthesis of unsymmetrical diaryl ketones. It can be conducted on a gram scale under mild and open-flask conditions with good functional group compatibility, avoiding the addition of expensive and/or toxic metals.

Chlorinated polyvinylchloride (CPVC) nanofiber mats were prepared by an electrospinning technique, and then treated with amines of different chemical structures, followed by immobilization of palladium catalysts (CPVC–NH2–Pd), which have been demonstrated as efficient, stable and easily recyclable heterogeneous catalysts. Their catalytic activities could be correlated with the binding energies of the palladium species with the amine chelating ligands.

An efficient and recyclable ligand-free heterogeneous catalyst has been prepared by the immobilization of palladium onto ground pearl shell powders (Pd/shell powders, Pd/SP). The catalytic activity and recyclability of the prepared Pd/SP along with the charcoal and calcium carbonate supported palladium (Pd/C and Pd/CaCO3) catalysts have been evaluated using the reductive homocoupling of aromatic halides. Pd/SP not only has higher catalytic activity, but also exhibits much stronger stability than Pd/C and Pd/CaCO3. The remarkable Pd/SP stability has been attributed to the chelation of palladium species with the surface chitin and protein molecules of the supported pearl shell powders. The X-ray photoelectron spectroscopy (XPS) studies show that the reductive Pd0 species can be regenerated in situ from the oxidative Pd2+ species for the Pd/SP catalyzed reductive homocoupling of aromatic halides in ethanol/DMSO solution, suggesting that the heterogeneous and homogeneous palladium catalysis proceeds through a similar Pd0/Pd2+ cycle catalytic mechanism.

The acidic ionic liquid (IL) functionalized polymer (PDVB-SO3H-[C3vim][SO3CF3]) possesses abundant nanoporous structures, strong acid strength and unique capability for deconstruction of crystalline cellulose into sugars in ILs. The polymer shows much improved catalytic activities in comparison with mineral acids, homogeneous acidic ionic liquids and the acidic resins such as Amberlyst 15. The enhanced catalytic activity found in the polymer is attributed to synergistic effects between the strongly acidic group and the ILs grafted onto the polymer, which by itself is capable of breaking down the crystalline structures of cellulose. This study may help develop cost-effective and green routes for conversion of biomass to fuels.

We report here a generalized synthesis of various crystalline mesoporous metal oxides including CeO2, Cr2O3, Fe2O3, SnO2, Ce0.5Zr0.5O2, TiO2, Al2O3 and ZrO2 from the self-assembly of a basic poly 4-vinylpyridine (P4VP) template with various metal precursors based on their strong acid–base interaction under high temperature (180 °C) hydrothermal conditions. Using the typically crystalline mesoporous metal oxide of CeO2, after removing the template by calcination at 550 °C and loading with various transition metal oxides such as MnOx, various transition metal oxide functionalized crystalline mesoporous CeO2 (MnOx/P4VP–CeO2) were obtained. X-ray diffraction (XRD) patterns show that the resulting mesoporous metal oxides exhibit a high degree of crystallinity, and the transition metal oxides active sites have been successfully loaded into these samples. N2 sorption–desorption isotherms, SEM images show that the resulting crystalline mesoporous metal oxides, such as CeO2, have a large BET surface area (94 m2 g−1) and abundant mesopores, which exhibit monolithic morphology with crystal sizes ranging from 5 to 15 μm, giving a uniform pore size centered at 5 nm. XPS spectra show that the active sites such as MnOx exhibit the phases of MnO2 and Mn2O3 in P4VP–CeO2. H2-TPR curves show that MnOx/P4VP–CeO2 exhibits decreased reductive temperatures of both active sites of the MnOx and P4VP–CeO2 supporter when compared with the samples reported previously. More importantly, MnOx/P4VP–CeO2 exhibits much better catalytic activities and good recyclability for catalyzing the oxidation of benzene than that of MnOx loaded commercially crystalline CeO2, which will be very important for their wide applications for VOCs removal in industry.

Graphene with its two-dimensional sheet of sp2-hybridized carbon is a hot topic in the fields of materials and chemistry due to its unique features. Herein, we demonstrate that sulfated graphene is an efficient solid catalyst for acid-catalyzed liquid reactions. The sulfated graphene was synthesized from a facile hydrothermal sulfonation of reduced graphene oxide with fuming sulfuric acid at 180 °C. Combined characterizations of XRD, Raman, and AFM techniques show that G-SO3H has a sheet structure (1–4 layers). IR spectroscopy shows that G-SO3H has a SO bond, and the XPS technique confirms the presence of an S element in G-SO3H. Acid–base titration indicates that the acidic concentration of sulfonic groups in the sulfated graphene is 1.2 mmol g−1. TG curves shows that the decomposition temperature (268 °C) of the sulfonic groups on the sulfated graphene is much higher than that of conventional SO3H-functionalized ordered mesoporous carbon (237 °C). Catalytic tests of the esterification of acetic acid with cyclohexanol, the esterification of acetic acid with 1-butanol, the Peckmann reaction of resorcinol with ethyl acetoacetate, and the hydration of propylene oxide show that sulfated graphene is much more active than the conventional solid acid catalysts of Amberlyst 15, OMC-SO3H, SO3H-functionalized ordered mesoporous silica (SBA-15-SO3H), graphene oxide, and reduced graphene oxide, which is attributed to the fact that the sulfated graphene almost has no limitation of mass transfer due to its unique sheet structure. Very importantly, the sulfated graphene has extraordinary recyclability in these reactions, which is attributed to the stable sulfonic groups on the sulfated graphene. The advantages, including high activities and good recyclability as well as simple preparation, are potentially important for industrial applications of the sulfated graphene as an efficient heterogeneous solid acid catalyst in the future.

Strong acidic ionic liquids functionalized, ordered and stable mesoporous phenol–formaldehyde resins (OMR-ILs) monoliths have been successfully synthesized from the treatment of ordered mesoporous resins (OMR-[HMTA]) using 1,3-propanesultone, followed by ion exchanged using various strong acids. The OMR-[HMTA] samples could be synthesized by the assembly of block copolymer template of F127 with preformed resol, which could be obtained from heating a mixture of phenol and formaldehyde at 70 °C; during curing processes, certain contents of the hexamethyltetramine (HMTA) cross linker were also introduced, after hydrothermal treatment at 200 °C for 20 h, calcination at 360 °C under nitrogen, OMR-[HMTA] samples with opened mesopores were obtained. Characterizations suggest that OMR-ILs have ordered and stable mesospores, high BET surface areas, and strong acid strength. Interestingly, OMR-ILs show much higher catalytic activities and recyclability in the esterification of acetic acid with cyclohexanol, hydration of propylene oxide, Peckmann reaction of resorcinol with ethyl acetoacetate and transesterification of tripalmitin with methanol than those of Amberlyst 15, sulfonic group functional ordered mesoporous silicas and acidic zeolites, which were even comparable with that of H2SO4. The unique features of OMR-ILs such as superior thermal stability, excellent catalytic activities and recyclability, will be potentially important for their applications in industry.

A highly efficient approach to (Z)-conjugated enynes has been developed by utilizing an Au(III)-catalyzed ring opening reaction of 1-cyclopropyl-2-yn-1-ols with nucleophiles under mild conditions; the method is valuable due to the excellent yield and high regio- and stereoselectivity.