Facile synthesis of microporous carbon through a soft-template pathway and its performance in desulfurization and denitrogenation

Wormlike/lamellar microporous carbons were prepared by using long alkyl chain primary amine hydrochloride as the template and resorci- nol/formaldehyde as the carbon source under highly acidic conditions. The template can be eliminated by high temperature treatment under an inert atmosphere. The obtained carbon materials were characterized by N2 adsorption-desorption, transmission electron microscopy, ther- mogravimetry and scanning electron microscopy. The results show that dodecylamine hydrochloride surfactant can be used as the template of wormlike micropores structure while octadecylamine hydrochloride results in both lamellar and wormlike micropores. The obtained carbon materials have the similar pore size in the range of 0.5-0.59 nm, but with various morphologies such as monolith, spheres, and coralline. The microporous carbon obtained from dodecylamine hydrochloride surfactant shows good adsorption performance to remove the refractory sulfur compounds and nitrogen-containing compounds in fuel.

Core-shell meso/microporous carbon host for sulfur loading toward applications in lithium-sulfur batteries

Lithium-sulfur（Li-S） batteries belong to one of the promising technologies for high-energy-density rechargeable batteries.However,sulfur cathodes suffer from inherent problems of its poor electronic conductivity and the shuttling of highly dissoluble lithium polysulfides generated during the cycles.Loading sulfur into porous carbons has been proved to be an effective approach to alleviate these issues.Mesoporous and microporous carbons have been widely used for sulfur accommodation,but mesoporous carbons have poor sulfur confinement,whereas microporous carbons are impeded by low sulfur loading rates.Here,a core-shell carbon,combining both the merits of mesoporous carbon with large pore volume and microporous carbon with effective sulfur confinement,was prepared by coating the mesoporous CMK-3 with a microporous carbon（MPC） shell and served as the carbon host（CMK-3 @MPC） to accommodate sulfur.After sulfur infusion,the as-obtained S/（CMK-3@MPC） cathode delivered a high initial capacity of up to 1422 mAh·g-1 and sustained 654 mAh·g-1 reversible specific capacity after 36 cycles at 0.1 C.The good performance is ascribed to the unique core-shell structure of the CMK-3@MPC matrix,in which sulfur can be effectively confined within the meso/microporous carbon host,thus achieving simultaneously high electrochemical utilization.

One-pot synthesis of N-doped petroleum coke-based microporous carbon for high-performance CO_(2) adsorption and supercapacitors

Waste resource utilization of petroleum coke is crucial for achieving global carbon emission reduction.Herein,a series of N-doped microporous carbons were fabricated from petroleum coke using a one-pot synthesis method.The as-prepared samples had a large specific surface area(up to 2512 m^(2)/g),a moderate-high N content(up to 4.82 at.%),and high population(55%)of ultra-micropores(<0.7 nm).Regulating the N content and ultra-microporosity led to efficient CO_(2)adsorption and separation.At ambient pressure,the optimal N-doped petroleum coke-based microporous carbon exhibited the highest CO_(2)uptake of 4.25 mmol/g at 25℃ and 6.57 mmol/g at 0℃.These values are comparable or even better than those of numerous previously reported adsorbents prepared by multistep synthesis,primarily due to the existence of ultra-micropores.The sample exhibited excellent CO_(2)/N_(2)selectivity at 25℃ owing to the abundant basic pyridinic and pyrrolic N species;and showed superior CO_(2)adsorption-desorption cycling performance,which was maintained at 97% after 10 cycles at 25℃.Moreover,petroleum coke-based microporous carbon,with a considerably high specific surface area and hierarchical pore structure,exhibited excellent electrochemical performance over the N-doped sample,maintaining a favorable specific capacitance of 233.25F/g at 0.5 A/g in 6 mol/L KOH aqueous electrolyte.This study provides insight into the influence of N-doping on the porous properties of petroleum coke-based carbon.Furthermore,the as-prepared carbons were found to be promising adsorbents for CO_(2)adsorption,CO_(2)/N_(2)separation and electrochemical application.

Zinc tartrate oriented hydrothermal synthesis of microporous carbons for high performance supercapacitor electrodes

A novel zinc tartrate oriented hydrothermal synthesis of microporous carbons was reported. Zinc–organic complex obtained via a simple chelation reaction of zinc ions and tartaric acid is introduced into the networks of resorcinol/formaldehyde polymer under hydrothermal condition. After carbonization process, the resultant microporous carbons achieve high surface area（up to 1255 m^2/g） and large mean pore size（1.99 nm） which guarantee both high specific capacitance（225 F/g at 1.0 A/g） and fast charge/discharge operation（20 A/g） when used as a supercapacitor electrode. Besides, the carbon electrode shows good cycling stability, with 93% capacitance retention at 1.0 A/g after 1000 cycles. The welldesigned and high-performance microporous carbons provide important prospects for supercapacitor applications.

Characterization of Microporous Activated Carbon Electrodes for Electric Double-layer Capacitors

Activated carbons(ACs) with a wide range of surface areas were made from petroleum coke by means of KOH activation. The electrochemical characterization was carried out for several activated carbons used as polarizable electrodes of electric double-layer capacitors(EDLCs) in an aqueous electrolytic solution. The porous structures and electrochemical double-layer capacitance of the activated carbons were investigated by virtue of nitrogen gas adsorption and constant current cycling(CCC) methods. The relationship among the surface area, pore volume of the activated carbons and specific double-layer capacitance was discussed. It was found that the specific capacitance of ACs increased linearly with the increase of surface area. The presence of mesopores in the activated carbons with very high surface area(>2000 m\+2/g) was not very effective for them to be used as EDLCs. The influence of chemical characteristics of the activated carbons on the double layer formation could be considered to be negligible.

A Fe-N-C catalyst with highly dispersed iron in carbon for oxygen reduction reaction and its application in direct methanol fuel cells

Exploring non‐precious metal catalysts for the oxygen reduction reaction （ORR） is essential for fuel cells and metal–air batteries. Herein, we report a Fe‐N‐C catalyst possessing a high specific surface area （1501 m2/g） and uniformly dispersed iron within a carbon matrix prepared via a two‐step pyrolysis process. The Fe‐N‐C catalyst exhibits excellent ORR activity in 0.1 mol/L NaOH electrolyte （onset potential, Eo=1.08 V and half wave potential, E1/2=0.88 V vs. reversible hydrogen electrode） and 0.1 mol/L HClO4 electrolyte （Eo=0.85 V and E1/2=0.75 V vs. reversible hydrogen electrode）. The direct methanol fuel cells employing Fe‐N‐C as the cathodic catalyst displayed promising per‐formance with a maximum power density of 33 mW/cm2 in alkaline media and 47 mW/cm2 in acidic media. The detailed investigation on the composition–structure–performance relationship by X‐ray diffraction, X‐ray photoelectron spectroscopy and Mo-ssbauer spectroscopy suggests that Fe‐N4, together with graphitic‐N and pyridinic‐N are the active ORR components. The promising direct methanol fuel cell performance displayed by the Fe‐N‐C catalyst is related to the intrinsic high catalytic activity, and critically for this application, to the high methanol tolerance.

Metal-Organic Framework-Derived Metallic Carbon with Record High Radon Gas Capture Performance

Developing efficient adsorbents for radon(Rn)capture from the ambient environment is of paramount importance for public health.However,it poses a great challenge due to the chemical inertness and extremely low molar concentration of Rn in air.Herein,we report a zeolite imidazolate frameworkderived metallic carbon adsorbent(Zn@NPC)with record high Rn removal performance under ambient conditions.Upon one-step pyrolysis,the prepared Zn@NPC possesses pores with a preference for Rn and atomically dispersed Zn sites,achieving a high Rn removal efficiency that doubles in adsorption coefficient(9.47 L·g^(−1))and triples in adsorption kinetic coefficient(20.25 mL·g^(−1)·min^(−1))over the benchmark Rn adsorbent coconut activated charcoal.Density functional theory calculations elucidate the important role of the metal polarization effect,which cooperates with the pore size confinement effect to boost the overall Rn adsorption performance.This work launches a promising alternative for practical Rn capture.

Boron-doped microporous nano carbon as cathode material for high-performance Li-S batteries

In this study, a boron-doped microporous carbon （BMC）/sulfur nanocomposite is synthesized and applied as a novel cathode material for advanced Li-S batteries. The cell with this cathode exhibits an ultrahigh cycling stability and rate capability. After activation, a capacity of 749.5 mAh/g was obtained on the 54t＂ cycle at a discharge current of 3.2 A/g. After 500 cycles, capacity of 561.8 mAh/g remained （74.96% retention）, with only a very small average capacity decay of 0.056%. The excellent reversibility and stability of the novel sulfur cathode can be attributed to the ability of the boron-doped microporous carbon host to both physically confine polysulfides and chemically bind these species on the host surface. Theoretical calculations confirm that boron-doped carbon is capable of significantly stronger interactions with the polysulfide species than undoped carbon, most likely as a result of the lower electronegativity of boron. We believe that this doping strategy can be extended to other metal-air batteries and fuel cells, and that it has promising potential for many different applications.

Breakthrough CO_2 adsorption in bio-based activated carbons

In this work, the effects of different methods of activation on CO2 adsorption performance of activated carbon were studied. Activated carbons were prepared from biochar, obtained from fast pyrolysis of white wood, using three different activation methods of steam activation, CO2 activation and Potassium hydroxide（KOH） activation. CO2 adsorption behavior of the produced activated carbons was studied in a fixed-bed reactor set-up at atmospheric pressure, temperature range of 25–65°C and inlet CO2 concentration range of10–30 mol% in He to determine the effects of the surface area, porosity and surface chemistry on adsorption capacity of the samples. Characterization of the micropore and mesopore texture was carried out using N2 and CO2 adsorption at 77 and 273 K, respectively.Central composite design was used to evaluate the combined effects of temperature and concentration of CO2 on the adsorption behavior of the adsorbents. The KOH activated carbon with a total micropore volume of 0.62 cm3/g and surface area of 1400 m2/g had the highest CO2 adsorption capacity of 1.8 mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30 mol% CO2 and 25°C. The performance of the adsorbents in multi-cyclic adsorption process was also assessed and the adsorption capacity of KOH and CO2 activated carbons remained remarkably stable after50 cycles with low temperature（160°C） regeneration.