The dehydrogenation of ethanol to acetaldehyde is of great importance in synthetic chemistry and the fine chemical industry. In this study, we report that a mesoporous-carbon-supported Cu catalyst exhibited a high reaction rate and excellent product selectivity in ethanol dehydrogenation to acetaldehyde. Under the severe conditions of an ethanol concentration of 15 vol % and a gaseous hourly space velocity of 8 600 h⁻¹, the Cu-based carbon catalyst maintains a conversion of ≈73 % and an acetaldehyde selectivity of ≈94 % at 553 K. Meanwhile, a prominent space time yield (225 h⁻¹) of acetaldehyde is obtained, which is far higher than that (112 h⁻¹) on the mesoporous-SBA-15-supported Cu catalyst. Ethanol adsorption studies prove that the enrichment of the carbon support for reactants makes a contribution to the high reaction rate. Importantly, kinetic measurements indicate that the scarce surface groups of the mesoporous carbon support minimize the secondary reactions of acetaldehyde, which are generally catalyzed by OH and/or COOH on the surface of the support as exemplified by the mesoporous-SBA-15-supported Cu catalyst. This accounts for the excellent selectivity toward acetaldehyde on the mesoporous-carbon-supported Cu catalyst. Therefore, these surface characteristics of the carbon support show great advantages in this dehydrogenation reaction.

The front cover artwork for Issue 18/2015 is provided by the Advanced Energy Materials Group of Dalian University of Technology, P.R. China. The image shows that Cu nanoparticles supported on a mesoporous carbon act as an active catalyst for the dehydrogenation of ethanol to acetaldehyde with excellent selectivity and in an atom-economic fashion. See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201500501.

In heterogeneous catalysis, supports play a crucial role in modulating the geometric and electronic structure of the active metal phase for optimizing the catalytic performance. A γ-Al₂O₃ nanosheet that contains 27 % pentacoordinate Al³⁺ sites can nicely disperse and stabilize raft-like Pt-Sn clusters as a result of strong interactions between metal and support. Consequently, there are strong electronic interactions between the Pt and Sn atoms, resulting in an increase in the electron density of the Pt sites. When used in the propane dehydrogenation reaction, this catalyst displayed an excellent specific activity for propylene formation with >99 % selectivity, and superior anti-coking and anti-sintering properties. Its exceptional ability to maintain the high activity and stability at ultrahigh space velocities further showed that the sheet construction of the catalyst facilitated the kinetic transfer process.

In heterogeneous catalysis, supports play a crucial role in modulating the geometric and electronic structure of the active metal phase for optimizing the catalytic performance. A γ-Al₂O₃ nanosheet that contains 27 % pentacoordinate Al³⁺ sites can nicely disperse and stabilize raft-like Pt-Sn clusters as a result of strong interactions between metal and support. Consequently, there are strong electronic interactions between the Pt and Sn atoms, resulting in an increase in the electron density of the Pt sites. When used in the propane dehydrogenation reaction, this catalyst displayed an excellent specific activity for propylene formation with >99 % selectivity, and superior anti-coking and anti-sintering properties. Its exceptional ability to maintain the high activity and stability at ultrahigh space velocities further showed that the sheet construction of the catalyst facilitated the kinetic transfer process.

Porous carbon anodes with a controllable V_mes/V_mic ratio were synthesized through the self-assembly of poly(benzoxazine-co-resol) and the simultaneous hydrolysis of tetraethyl orthosilicate (TEOS) followed by carbonization and removal of silica. The V_mes/V_mic ratio of the carbon can be controlled in the range of approximately 1.3–32.6 through tuning the amount of TEOS. For lithium-ion battery anodes, a correlation between the electrochemical performance and V_mes/V_mic ratio has been established. A high V_mes/V_mic ratio in porous carbons is favorable for enhancing the accessibility of Li ions to active sites provided by the micropores and for achieving good lithium storage performance. The obtained porous carbon exhibits a high reversible capacity of 660 mAh g⁻¹ after 70 cycles at a current density of 100 mA g⁻¹. Moreover, at a high current density of 3000 mA g⁻¹, the capacity still remains at 215 mAh g⁻¹, showing a fast charge-discharge potential. This synthesis method relying on modified benzoxazine chemistry with the hydrolysis of TEOS may provide a new route for the development of mesoporous carbon-based electrode materials.

In this study, a method is developed to fabricate Fe₃O₄@C particles with a coaxial and penetrated hollow mesochannel based on the concept of “confined nanospace pyrolysis”. The synthesis involves the production of a polydopamine coating followed by a silica coating on a rod-shaped β-FeOOH nanoparticle, and subsequent treatment by using confined nanospace pyrolysis and silica removal procedures. Typical coaxial hollow Fe₃O₄@C possesses a rice-grain morphology and mesoporous structure with a large specific surface area, as well as a continuous and flexible carbon shell. Electrochemical tests reveal that the hollow Fe₃O₄@C with an open-ended nanostructure delivers a high specific capacity (ca. 864 mA h g⁻¹ at 1 A g⁻¹), excellent rate capability with a capacity of about 582 mA h g⁻¹ at 2 A g⁻¹, and a high Coulombic efficiency (>97 %). The excellent electrochemical performance benefits from the hollow cavity with an inner diameter of 18 nm and a flexible carbon shell that can accommodate the volume change of the Fe₃O₄ during the lithium insertion/extraction processes as well as the large specific surface area and open inner cavity to facilitate the rapid diffusion of lithium ions from electrolyte to active material. This fabrication strategy can be used to generate a hollow or porous metal oxide structure for high-performance Li-ion batteries.

A new synthetic approach for the fabrication of microporous carbon materials (HCMs) by using discrete chelating zinc species as dynamic molecular porogens to create extra micropores that enhance their CO₂-adsorption capacity and selectivity is reported. During the carbonization process, the evaporation of the in situ-formed Zn species would create additional nanochannels that contribute to the additional micropore volume for CO₂ adsorption. The resultant HCMs show an increased number of micropores, with sizes in the range 0.7–1.0 nm and a high CO₂-adsorption capacity of 5.4 mmol g⁻¹ (23.8 wt %) at 273 K and 3.8 mmol g⁻¹ (16.7 wt %) at 298 K and 1 bar, which are superior to those of most carbon-based adsorbents with N-doping or high specific surface areas. Dynamic gas-separation measurements, by using 16 % CO₂ in N₂ (v/v) as a feedstock, demonstrated that CO₂ could be effectively separated from N₂ under ambient conditions and shows a high separation factor (S=110) for CO₂ over N₂, thereby reflecting a strongly competitive CO₂-adsorption capacity. If the feedstock contained water vapor, the dynamic capacity of CO₂ was almost identical to that measured under dry conditions, thus indicating that the carbon material had excellent tolerance to humidity. Easy CO₂ release could be realized by purging an argon flow through the fixed-bed adsorber at 298 K, thus indicating good regeneration ability.

An effective strategy is explored for the in situ generation of a Cu₂S/tubular mesoporous carbon composite by exploiting the charge–discharge processes of a S/C composite on a copper-foil current collector. By studying the reaction mechanism, we discover that the dissolved polysulfide ions (from the reaction of pristine sulfur) and inserted Li⁺ are firmly anchored by the copper ions released from the copper foil, which forms insoluble Cu_xS intermediates in the mesopore channels of the carbon matrix. Moreover, the new electrochemically active Cu_xS intermediates are gradually converted to the final product, Cu₂S, during subsequent cycles. The as-prepared Cu₂S nanoparticles are highly dispersed throughout the tubular mesoporous carbon, and the Cu₂S/C composite exhibits a high reversible capacity of 270 mAh g⁻¹ at 0.2 C over 300 cycles, with the negligible capacity loss, when used as a cathode material for a lithium-ion battery. Furthermore, the composite shows an outstanding rate capability with a reversible capacity of 225 mAh g⁻¹ under a high rate of 10 C. This work provides a convenient platform for the controlled synthesis of metal sulfides for lithium-storage applications.

Novel multifunctional composites composed of highly dispersed nanosized Fe₂O₃ particles, a tubular mesoporous carbon host, and a conductive polypyrrole (PPy) sealing layer are hierarchically assembled via two facile processes, including bottom-up introduction of Fe₂O₃ nanoparticles in tubular mesoporous carbons, followed by in situ surface sealing with the PPy coating. Fe₂O₃ particles are well-dispersed within the carbon matrix and PPy is spatially and selectively coated onto the external surface and the pore entrances of the Fe₂O₃@C composite, thereby bridging the composite particles together into a larger unit. As an anode material for Li-ion batteries (LIBs), the PPy-coated Fe₂O₃@C composite exhibits stable cycle performance. Additionally, the PPy-coated Fe₂O₃@C composite also possesses fast electrode reaction kinetics, high Fe₂O₃ use efficiency, and large volumetric capacity. The excellent electrochemical performance is associated with a synergistic effect of the highly porous carbon matrix and the conducting PPy sealing layer. Such multifunctional configuration prevents the aggregation of NPs and maintains the structural integrity of active materials, in addition to effectively enhancing the electronic conductivity and warranting the stability of as-formed solid electrolyte interface (SEI) films. This nanoengineering strategy might open new avenues for the design of other multifunctional composite architectures as electrode materials in order to achieve high-performance LIBs.

In the past decades, carbon materials retain great development because of their indispensable applications in energy storage and conversion, adsorption, catalysis, and others. The evidence is that a number of new structured carbon materials have been synthesized from molecular level, bottom-up strategy. To date, it has been possible to synthesize carbon materials with defined nanostructure and morphology, tunable surface area, and pore size. In this review, we focus on discussing the recent development of chemically synthesized carbon materials with intriguing nanostructure and morphology. For convenience, these materials are grouped into four categories — 0D quantum dots and spheres; 1D fibers, tubes, and wires; 2D films and membranes; and 3D monolithic structure. In each category, materials synthesis strategies are discussed, whereas their applications are briefly touched. In the last section, we made a brief summary and discussed the future perspectives of carbon materials. We expect that this review not only summarizes the main achievements in this area, but also creates interdisciplinary activities in between carbon chemistry and other research areas.

Size-uniform and highly dispersed bimetallic Au–Pd nanoparticles were formed in situ and confined in tubular mesoporous carbon by successive incipient wetness impregnation and a thermal annealing method. The bimodal mesoporous carbon (CMK-5) encapsulated Au–Pd nanoparticles with 1 wt % metal loading enables superior activity compared with mono-modal mesoporous carbon for benzyl alcohol oxidation. A conversion of >99 % and selectivity of >99 % can be reached within 3 h under mild conditions, for example, at 80 °C and at atmospheric pressure. It is found that during the catalyst preparation, the Au and Pd precursor impregnation sequence is a key factor to the formation of Au–Pd nanoparticles under identical conditions. A relatively high activity is realized by the first impregnation of the Au precursor, followed by the second impregnation of the Pd precursor. The crystalline structure and distribution of Au–Pd nanoparticles are characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), and XRD. It is found that a larger proportion of surface-exposed Pd atoms in Au–Pd nanoparticles have a positive effect on catalytic activity. The Au–Pd nanoparticles have a narrow size distribution that is concentrated at approximately 4 nm. TEM and N₂ adsorption results reveal that the catalyst has a large surface area and well-developed bimodal pore interconnectivity, which contribute to its excellent activity. The used catalyst retained a high selectivity but conversion decreased with recycling. The deactivation mechanism was attributed to the tiny amount of incompletely removed benzaldehyde adsorbed onto the active surface, which blocked access from the active sites to benzyl alcohol. Importantly, the used catalyst can be recovered by a simple heat treatment at 200 °C in air after the catalytic cycles have completed; the adsorbed benzaldehyde is removed from the active surface. Hence, Au–Pd nanoparticles confined in tubular mesoporous carbon can be used as an alternative method to develop highly dispersed nanocatalysts to improve catalytic efficiency.

High-temperature, stable core–shell catalysts for ammonia decomposition have been synthesized. The highly active catalysts, which were found to be also excellent model systems for fundamental studies, are based on α-Fe₂O₃ nanoparticles coated by porous silica shells. In a bottom-up approach, hematite nanoparticles were firstly obtained from the hydrothermal reaction of ferric chlorides, L-lysine, and water with adjustable average sizes of 35, 47, and 75 nm. Secondly, particles of each size could be coated by a porous silica shell by means of the base-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) with cetyltetramethylammonium bromide (CTABr) as porogen. After calcination, TEM, high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray (EDX), XRD, and nitrogen sorption studies confirmed the successful encapsulation of hematite nanoparticles inside porous silica shells with a thickness of 20 nm, thereby leading to composites with surface areas of approximately 380 m² g⁻¹ and iron contents between 10.5 and 12.2 wt %. The obtained catalysts were tested in ammonia decomposition. The influence of temperature, iron oxide core size, possible diffusion limitations, and dilution effects of the reagent gas stream with noble gases were studied. The catalysts are highly stable at 750 °C with a space velocity of 120 000 cm³ g_cat⁻¹ h⁻¹ and maintained conversions of around 80 % for the testing period time of 33 h. On the basis of the excellent stability under reaction conditions up to 800 °C, the system was investigated by in situ XRD, in which body-centered iron was determined, in addition to FeN_x, as the crystalline phase under reaction conditions above 650 °C.