Influence of Preparation Conditions on Structural Stability of Ordered Mesoporous Carbons Synthesized by Evaporation-induced Triconstituent Co-assembly Method

Various ordered mesoporous carbons （OMCs） have been prepared by evaporation-induced trieonstituent co-assembly method. Their mesostructural stability under different carbon content, aging time and acidity were conveniently monitored by X-ray diffraction, transmission electron microscopy, and N2 sorption isotherms techniques. The results show mesostruetural stability of OMCs is enhanced as the carbon content increases from 36% to 46%, further increasing carbon content deteriorates the mesostructural stability. Increasing aging time from 0.5 h to 5.0 h make the mesostructural stability go through an optimum （2.0 h） and gradually reduce framework shrinkage of the OMCs. Highly OMCs can only be obtained in the acidity range of 0.2-1.2 mol/L HC1, when the acidity is near the isoelectrie point of silica, the resulting OMCs have the best mesostructure stability. Under the optimum condition, the carbon content of 46%, aging time of 2.0 h, and 0.2 mol/L HCl, the resulting OMCs have the best mesostrueture stability and the highest BET surface areas of 2281 m2/g.

Mesoporous carbons as metal-free catalysts for propane dehydrogenation: Effect of the pore structure and surface property

Nanocarbon materials have been used as important metal-free catalysts for various reactions including alkane dehydrogenation.However,clarifying the active sites and tuning the nanocarbon structure for direct dehydrogenation have always been significantly challenging owing to the lack of fundamental understanding of the structure and surface properties of carbon materials.Herein,mesoporous carbon materials with different pore ordering and surface properties were synthesized through a soft-templating method with different formaldehyde/resorcinol ratios and carbonization temperatures and used for catalytic dehydrogenation of propane to propylene.The highly ordered mesoporous carbons were found to have higher catalytic activities than disordered and ordered mesoporous carbons,mainly because the highly ordered mesopores favor mass transportation and provide more accessible active sites.Furthermore,mesoporous carbons can provide a large amount of surface active sites owing to their high surface areas,which is favorable for propane dehydrogenation reaction.To control the surface oxygenated functional groups,highly ordered mesoporous carbons were carbonized at different temperatures(600,700,and 800℃).The propylene formation rates exhibit an excellent linear relationship with the number of ketonic C=O groups,suggesting that C=O groups are the most possible active sites.

P-doped mesoporous carbons for high-efficiency electrocatalytic oxygen reduction

Chemically modified carbonaceous materials have attained utmost attention in the fields of renewable energy storage and conversion,due to the controllable physicochemical properties,tailorable micro-/nanostructures,and respectable stability.Herein,P-doped mesoporous carbons were synthesized by using F127 as the soft template,organophosphonic acid as the P source and phenolic resin as the carbon source.Small amounts of iron species were introduced to act as a graphitization catalyst.The synthesized carbons exhibit the well-defined wormhole-like pore structure featuring high specific surface area and homogenously doped P heteroatoms.Notably,introducing iron species during the synthesis process can optimize the textural properties and the degree of graphitization of carbon materials.The doping amount of P has an important effect on the porous structure and the defect degree,which correspondingly influence the active sites and the oxygen reduction reaction(ORR)activity.The resultant material presents superior catalytic activity for the ORR,together with remarkably enhanced durability and methanol tolerance in comparison with the commercial Platinum catalyst,demonstrating the possibility for its use in electrode materials and electronic nanodevices for metal-air batteries and fuel cells.

Nitrogen-doped cobalt nanoparticles/nitrogen-doped plate-like ordered mesoporous carbons composites as noble-metal free electrocatalysts for oxygen reduction reaction

In this work, nitrogen-doped cobalt nanoparticlesinitrogen-doped plate-like ordered mesoporous carbons (N/Co/OMCs) were used as noble-metal free electrocatalysts with high catalytic efficiency. Compared with OMCs with long channel length, due to more entrances for catalytic target accessibility and a short pathway for rapid diffusion, the utilization efficiency of cobalt nanoparticles inside the plate-like OMCs with short pore length is well improved, which can take full advantage of porous structure in electrocatalysis and increase the utilization of catalysts. The active sites in N/Co/OMCs for oxygen reduction reaction (ORR) are highly exposed to oxygen molecule, which results in a high activity for ORR. By combination of the catalytic properties of nitrogen dopant, incorporation of Co nanoparticles, and structural properties of OMCs, the N/Co/plate-like OMCs are highly active noble-metal free catalysts for ORR in alkaline solution. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Pt nanoparticles entrapped in ordered mesoporous carbons:An efficient catalyst for the liquid-phase hydrogenation of nitrobenzene and its derivatives

Pt nanoparticles entrapped in ordered mesoporous CMK-3 carbons with p6mm symmetry were prepared using a facile impregnation method, and the resulting materials were characterized using X-ray diffraction spectroscopy, N2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The Pt nanoparticles were highly dispersed in the CMK-3 with 43.7% dispersion. The Pt/CMK-3 catalyst was an effective catalyst for the liquid-phase hydrogenation of nitrobenzene and its derivatives under the experimental conditions studied here. The Pt/CMK-3 catalyst was more active than commercial Pt/C catalyst in most cases. A highest turnover frequency of 43.8 s-1 was measured when the Pt/CMK-3 catalyst was applied for the hydrogenation of 2-methyl-nitrobenzene in ethanol under optimal conditions. It is worthy of note that the Pt/CMK-3 catalyst could be recycled easily, and could be reused at least fourteen times without any loss in activity or selectivity for the hydrogenation of nitrobenzene in ethanol.

Ammonia-treatment assisted fully encapsulation of Fe_2O_3 nanoparticles in mesoporous carbons as stable anodes for lithium ion batteries

To improve the initial coulombic efficiency and bulk density of ordered mesoporous carbons, active Fe203 nanoparticles were introduced into tubular mesopore channels of CMK-5 carbon, which possesses high specific surface area （〉1700 m2.g-1） and large pore volume （〉1.8 cm3-g-1）. Fine Fe203 nanoparticles with sizes in the range of 5-7 nm were highly and homogenously encapsulated into CMK-5 matrix through ammonia-treatment and subsequent pyrolysis method. The Fe203 loading was carefully tailored and designed to warrant a high Fe203 content and adequate buffer space for improving the electrochemical performance. In particular, such Fe203 and mesoporous carbon composite with 47 wt% loading exhibits a considerably stable cycle performance （683 mAh.g-1 after 100 cycles, 99% capacity retention against that of the second cycle） as well as good rate capability. The fabrication strategy can effectively solve the drawback of single material, and achieve a high-performance lithium electrode material.

Effect of the pore length and orientation upon the electrochemical capacitive performance of ordered mesoporous carbons

By utilizing hard template method to adjust the mesopore length, and alkali activation to generate micro pores, two hierarchical porous carbons (HPCs) were prepared. With controlling of their mesopore length and the activation conditions, the complex system composed by HPCs and electrolyte was simplified and the effect of mesopore length on the performance of HPCs as electrodes in supercapacitors was investigated. It is found that with the mesopore length getting smaller, the ordered area gets smaller and the aggregation occurs, which is caused by the high surface energy of small grains. HPC with long pores (HPCL) exhibits a donut-like morphology with well-defined ordered mesopores and a regular orientation while in HPC with short pores (HPCS), short mesopores are only orderly distributed in small regions. Longer ordered channels form unobstructed ways for ions transport in the particles while shorter channels, only orderly distributed in small areas, results in blocked paths, which may hinder the electrolyte ions transport. Due to the unobstructed structure, HPCL exhibits good rate capability with a capacitance retention rate over 86% as current density increasing from 50 mA/g to 1000 mA/g. The specific capacitance of HPCL derived from the cyclic voltammetry test at 10 mV/s is up to 201.72 F/g, while the specific capacitance of HPCS is only 193.65 F/g. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Simple Synthesis of Magnetic Mesoporous Carbons with High Surface Areas by Soft-template Method

Magnetic Fe-containing ordered mesoporous carbons （Fe/OMCs） with high surface areas and pore volume were synthesized through a simple soft-template route, wherein phenolic resin was used as a carbon precursor, triblock copolymer F127 as a template agent, tetraethyl orthosilicate （TEOS） as a silica precursor and hydrated iron nitrate as an iron source. The effects of carbonization temperature, loading degree of TEOS on the structural parameters of these Fe/OMCs were evaluated by X-ray diffraction （XRD） and Nz sorption analysis. The ordering, the specific surface area and the total pore volumes increased with the increase of carbonization temperature from 600 to 850 ~C. And the specific surface area and the total pore volumes increased with the increase of TEOS loading.

The self-assembly of gold nanoparticles in large-pore ordered mesoporous carbons

Simple encapsulation of 3 nm gold nanoparticles in ordered mesoporous carbon with large pores of 17 nm and thick pore walls of 16 nm was achieved by a metal–ligand coordination assisted-selfassembly approach.Polystyrene-block-polyethylene-oxide(PS-b-PEO)diblock copolymer with a large molecular weight of the PS chain and mercaptopropyltrimethoxysilane were used as the template and the metal ligand,respectively.Small-angle X-ray scattering,X-ray diffraction,transmission electron microscopy,and X-ray photoelectron spectroscopy showed that monodispersed aggregation-free gold nanoparticles approximately 3 nm in size were partially embedded in the large open pore structure of the ordered mesoporous carbon.The strong coordination between the gold species and the mercapto groups and the thick porous walls increased the dispersion of the gold nanoparticles and essentially inhibited particle aggregation at 600℃.The gold nanoparticles in the ordered mesoporous carbon are active and stable in the reduction of nitroarenes involving bulky molecules using sodium borohydride as a reducing agent under ambient conditions(30℃)in water.The large interconnected pore structure facilitates the mass transfer of bulky molecules.

Encapsulating polysulfide with high pyridinic nitrogen-doped ordered mesoporous carbons for long-life lithium-sulfur batteries

Rechargeable lithium-sulfur(Li-S)batteries are promising candidates for next-generation batteries because of their high theoretical specific capacity(1675 mAh/g)and specific energy(2600 Wh/kg);more-over,S is abundant,inexpensive,non-toxic,and environment friendly.However,the inherent insulating nature of S,discharge products of Li 2S,and dissolution of Li polysulfides(LiPSs)severely limit the practical applications of Li-S batteries.In this study,an N-doped ordered mesoporous carbon(NOMC)with a large specific surface area and high pyridinic N content was successfully prepared via the hard templating method.The synergetic effects of physical nanoconfinement and chemisorption restricted the LiPSs dissolution in the electrolyte.Graphitic N improved the electrical conductivity of the C materials,and pyridinic N effectively adsorbed the LiPSs,thereby inhibiting the shuttling of polysulfides in the electrolyte.The obtained C material was used as an S host,and the resultant S@NOMC composite exhibited a first discharge capacity of 853 mAh/g.The capacity of the composite was retained at 679 mAh/g after 500 cycles at 1 C,which corresponds to a decay rate of 0.042%per cycle.

Enhanced activation of peroxymonosulfate by Fe/N co-doped ordered mesoporous carbon with dual active sites for efficient removal of m-cresol

The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,the complexation of N elements in urea could anchor Fe,and the formation of C3N4during urea pyrolysis could also prevent migration and aggregation of Fe species,which jointly improve the dispersion and stability of Fe.The FeN4sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation,while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process,which together promote catalytic degradation of m-cresol by PMS activation.Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO_(4)^(-)·and·OH,and partially based on·OH as the active components,and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed.This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.

Core-shell mesoporous carbon hollow spheres as Se hosts for advanced Al-Se batteries

Incorporating a selenium(Se)positive electrode into aluminum(Al)-ion batteries is an effective strategy for improving the overall battery performance.However,the cycling stability of Se positive electrodes has challenges due to the dissolution of intermediate reaction products.In this work,we aim to harness the advantages of Se while reducing its limitations by preparing a core-shell mesoporous carbon hollow sphere with a titanium nitride(C@TiN)host to load 63.9wt%Se as the positive electrode material for Al-Se batteries.Using the physical and chemical confinement offered by the hollow mesoporous carbon and TiN,the obtained core-shell mesoporous carbon hollow spheres coated with Se(Se@C@TiN)display superior utilization of the active material and remarkable cycling stability.As a result,Al-Se batteries equipped with the as-prepared Se@C@TiN composite positive electrodes show an initial discharge specific capacity of 377 mAh·g^(-1)at a current density of 1000 mA·g^(-1)while maintaining a discharge specific capacity of 86.0 mAh·g^(-1)over 200 cycles.This improved cycling performance is ascribed to the high electrical conductivity of the core-shell mesoporous carbon hollow spheres and the unique three-dimensional hierarchical architecture of Se@C@TiN.

Mesoporous Carbon Nanofibers Loaded with Ordered PtFe Alloy Nanoparticles for Electrocatalytic Nitrate Reduction to Ammonia

Highly dispersed bimetallic alloy nanoparticle electrocatalysts have been demonstrated to exhibit exceptional performance in driving the nitrate reduction reaction(NO_(3)RR)to generate ammonia(NH_(3)).In this study,we prepared mesoporous carbon nanofibers(mCNFs)functionalized with ordered PtFe alloys(O-PtFe-mCNFs)by a composite micelle interface-induced co-assembly method using poly(ethylene oxide)-block-polystyrene(PEO-b-PS)as a template.When employed as electrocatalysts,O-PtFe-mCNFs exhibited superior electrocatalytic performance for the NO_(3RR)compared to the mCNFs functionalized with disordered PtFe alloys(D-PtFe-mCNFs).Notably,the NH_(3)production performance was particularly outstanding,with a maximum NH_(3)yield of up to 959.6μmol/(h·cm~2).Furthermore,the Faraday efficiency(FE)was even 88.0%at-0.4 V vs.reversible hydrogen electrode(RHE).This finding provides compelling evidence of the potential of ordered PtFe alloy catalysts for the electrocatalytic NO_(3)RR.

Guanine-assisted N-doped ordered mesoporous carbons as efficient capacity decaying suppression materials for lithium–sulfur batteries

Lithium–sulfur(Li–S)batteries are considered promising next-generation energy storage devices due to their high weight capacities and theoretical energy densities,which are significantly higher than those of conventional lithium-ion batteries.However,the sulfur cathode presents two major drawbacks,specifically low specific capacity caused by the poor electrical conductivities of the active materials and fast capacity decay caused by polysulfide dissolution/shuttling.Herein,a high-rate and high-stability dendritic material consisting of N-doped ordered mesoporous carbons(NOMCs)was successfully synthesized via a facile and low-cost calcination method.The highly ordered mesoporous carbon skeleton limited the growth of the sulfur nanofiller within its channels and provided the necessary electrical contact with the insulating sulfur.Furthermore,N-doped heteroatoms presented strong binding sites for trapping polysulfide intermediates,achieving high electrochemical activity,which promoted polysulfide conversion reactions.As a result,the prepared NOMC-2/S cathode material with 1.2-1.5 mg cm^(-2)of sulfur displayed excellent electrochemical performance with a high-rate capability of 460.5 m Ah g^(-1)at 1 C,a high specific capacity of 530.9 m Ah g^(-1)after 200 cycles at 0.1 C,and a decay rate of~0.19%per cycle.

Carbon dioxide capture using polyethylenimine-loaded mesoporous carbons

A high efficiency sorbent for CO2 capture was developed by loading polyethylenimine （PEI） on mesoporous carbons which possessed well-developed mesoporous structures and large pore volume. The physicochemical properties of the sorbent were characterized by N2 adsorption/desorption, scanning electron microscopy （SEM）, thermal gravimetric analysis （TG） and Fourier transform infrared spectroscopy （FT-IR） techniques followed by testing for CO2 capture. Factors that affected the sorption capacity of the sorbent were studied. The sorbent exhibited extraordinary capture capacity with CO2 concentration ranging from 5% to 80%. The optimal PEI loading was determined to be 65 wt.% with a CO2 sorption capacity of 4.82 mmol-CO2/g-sorbent in 15% CO2/N2 at 75℃, owing to low mass-transfer resistance and a high utilization ratio of the amine compound （63%）. Moisture had a promoting effect on the sorption separation of CO2. In addition, the developed sorbent could be regenerated easily at 100℃, and it exhibited excellent regenerability and stability. These results indicate that this PEI-loaded mesoporous carbon sorbent should have a good potential for CO2 capture in the future.

Preparation of mesoporous activated carbons from coal liquefaction residue for methane decomposition

Mesoporous activated carbons were prepared from direct coal liquefaction residue （CLR） by KOH activation method, and the experiments were carried out to investigate the effects of KOH/CLR ratio, solvent for mixing the CLR and KOH, and carbonization procedure on the resultant carbon texture and catalytic activity for catalytic methane decomposition （CMD）. The results showed that optimal KOH/CLR ratio of 2 ： 1; solvent with higher solubility to KOH or the CLR, and an appropriate carbonization procedure are conductive to improving the carbon pore structure and catalytic activity for CMD. The resultant mesoporous carbons show higher and more stable activity than microporous carbons. Additionally, the relationship between the carbon textural properties and the catalytic activity for CMD was also discussed.

Preparation of functional ordered mesoporous carbons and their application as the QCM sensor with ultra-low humidity

Ordered mesoporous carbon(OMCs)FDU-15 was synthesized through an EISA(Evaporation-Induced Self-Assembly)method,and the oxidized OMCs(FDU-15-COOH)were obtained by subsequent oxidation treatments in liquid phase to introduce functional groups,The samples were characterized by XRD,TEM,FT-IR and nitrogen adsorption-desorption test,The low humidity sensing performances of FDU-15 and FDU-15-COOH thin films were investigated by using a quartz crystal microbalance(QCM)transducer.The responses of FDU-15-COOH is higher than that of the pristine FDU-15 at very low humidity(<729 ppmv)with high long-term stability,implying that FDU-15-COOH is a good candidate for low humidity QCM sensor.

Electrochemical hydrogen evolution efficiently boosted by interfacial charge redistribution in Ru/MoSe_(2) embedded mesoporous hollow carbon spheres

The strong metal-support interaction inducing combined effect plays a crucial role in the catalysis reaction. Herein, we revealed that the combined advantages of MoSe_(2), Ru, and hollow carbon spheres in the form of Ru nanoparticles(NPs) anchored on a two-dimensionally ordered MoSe_(2) nanosheet-embedded mesoporous hollow carbon spheres surface(Ru/MoSe_(2)@MHCS) for the largely boosted hydrogen evolution reaction(HER) performance. The combined advantages from the conductive support, oxyphilic MoSe_(2), and Ru active sites imparted a strong synergistic effect and charge redistribution in the Ru periphery which induced high catalytic activity, stability, and kinetics for HER. Specifically, the obtained Ru/MoSe_(2)@MHCS required a small overpotential of 25.5 and 38.4 mV to drive the kinetic current density of 10 mA cm^(-2)both in acid and alkaline media, respectively, which was comparable to that of the Pt/C catalyst. Experimental and theoretical results demonstrated that the charge transfer from MoSe_(2) to Ru NPs enriched the electronic density of Ru sites and thus facilitated hydrogen adsorption and water dissociation. The current work showed the significant interfacial engineering in Ru-based catalysts development and catalysis promotion effect understanding via the metal-support interaction.

Magnetic motive, ordered mesoporous carbons with partially graphitized framework and controllable surface wettability： preparation, characterization and their selective adsorption of organic pollutants in water

Magnetically active, ordered and stable mesoporous carbons with partially graphitized networks and controllable surface wettability （PR-Fe-P123-800 and PR-Ni- P123-800） have been synthesized through direct carbonization of Fe or Ni functionalized, and ordered mesoporous polymers at 800℃, which could be synthesized from self assembly of resol （phenol/formaldehyde） with block copolymer template （P123） in presence of Fe3＋ or Ni2＋, and hydrothermal treatment at 200℃. PR-Fe-P123-800 and PR-Ni- P123-800 possess ordered and uniform mesopores, large BET surface areas, good stabilities, controllable surface wettability and partially graphitized framework. The above structural characteristics result in their enhanced selective adsorption property and good reusability for organic pollutants such as RhB, p-nitrophenol and n-heptane in water, which could be easily regenerated through separation under constant magnetic fields and washing with ethanol solvent. The unique magnetically active and adsorptive property found in PR-Fe-P123-800 and PR-Ni-P123-800 will be very important for them to be used as efficient absorbents for removal of various organic pollutants in water.

N-doped ordered mesoporous carbon as a multifunctional support of ultrafine Pt nanoparticles for hydrogenation of nitroarenes

Due to the advantages of high surface areas, large pore volumes and pore sizes, abundant nitrogen content that favored the metal-support interactions, N-doped ordered mesoporous carbons are regarded as a kind of fascinating and potential support for the synthesis of effective supported cat-alysts. Here, a N-doped ordered mesoporous carbon with a high N content （9.58 wt%）, high surface area （417 m^2/g）, and three-dimensional cubic structure was synthesized successfully and used as an effective support for immobilizing Pt nanoparticles （NPs）. The positive effects of nitrogen on the metal particle size enabled ultrasmall Pt NPs （about 1.0 ± 0.5 nm） to be obtained. Moreover, most of the Pt NPs are homogeneously dispersed in the mesoporous channels. However, using the ordered mesoporous carbon without nitrogen as support, the particles were larger （4.4 ± 1.7 nm） and many Pt NPs were distributed on the external surface, demonstrating the important role of the nitrogen species. The obtained N-doped ordered mesoporous material supported catalyst showed excellent catalytic activity （conversion 100%） and selectivity （〉99%） in the hydrogenation of halogenated nitrobenzenes under mild conditions. These values are much higher than those achieved using a commercial Pt/C catalyst （conversion 89% and selectivity 90%）. This outstanding catalytic perfor-mance can be attributed to the synergetic effects of the mesoporous structure, N-functionalized support, and stabilized ultrasmall Pt NPs. Moreover, such supported catalyst also showed excellent catalytic performance in the hydrogenation of other halogenated nitrobenzenes and nitroarenes. In addition, the stability of the multifunctional catalyst was excellent and it could be reused more than 10 times without significant losses of activity and selectivity. Our results conclusively show that a N-doped carbon support enable the formation of ultrafine metal NPs and improve the reaction ac-tivity and selectivity.