共查询到20条相似文献,搜索用时 15 毫秒
1.
Vicente Jiménez Ana Ramírez-Lucas Paula Sánchez José Luís Valverde Amaya Romero 《International Journal of Hydrogen Energy》2012
The hydrogen adsorption capacity of different types of carbon nanofibers (Platelet, Fishbone and Ribbon) and amorphous carbon has been measured as a function of pressure and temperature. Results have showed as the more graphitic/ordered carbon materials adsorbed less hydrogen than the more amorphous ones. After that and, with the aim of improve the hydrogen adsorption capacity of these carbon materials, they were functionalizated (oxygen surface groups incorporation) and Ni-modificated. Results also showed an important increase of the H2 adsorption capacity despite the porosity loss that took place after the treatments. Due to the advantages of functionalization and Ni-modification, both treatments were applied at the same time over the most promising carbon materials from the H2 adsorption point of view, observing again an improvement of the hydrogen adsorption capacity. Finally, the H2 adsorption capacity of chemically activated carbon materials increased considerably due the pore structure development and even more if activated materials were Ni-modificated. 相似文献
2.
Yan Li Donglin Zhao Yuntao Wang Risheng Xue Zengmin Shen Xingguo Li 《International Journal of Hydrogen Energy》2007
Carbon materials were obtained by the thermal decomposition of organic reagents, and different surface states are achieved by treatment in different conditions. SEM, XRD and BET were used to characterize the samples. Hydrogen storage of the samples was measured at liquid nitrogen temperature. Combining these results and others’ work, a mechanism for hydrogen storage in carbon materials is proposed that hydrogen is stored at different sites with different mechanisms. With this hypothesis, the hydrogen storage properties of carbon materials can be forecasted quantitatively. 相似文献
3.
Sustainable and renewable energy resources, as well as energy storage systems (ESSs), are amongst the current and critical global requirements. A comparative discussion on batteries, fuel cells and electrochemical capacitors (ECs) is presented. The mechanisms involved in various classes of ECs are also elaborated. Additionally, a historical background highlighting some of the major steps associated with EC development over the years is discussed in this review. In particular, carbon nanostructured materials have high potential in the development of ESSs, and hence this review presents an insight on the current ESSs with a strong bias towards these materials as ECs. The current status of carbon nanomaterials, such as carbon nanotubes, nanofibers, nano‐onions, nanorods, fullerenes and graphene nanosheets, in ECs is reviewed. The associated effects of nanostructural parameters, such as pore sizes and specific electro‐active areas, amongst others, in terms of energy storage capabilities are also discussed. Typical physicochemical characterisation techniques, which enrich understanding of their characteristics, are also reviewed. The discussion views set platforms for a variety of unique carbon nanomaterial designs with high prospective specific capacitance. Key porosity tailoring protocols, such as chemical activation, introduction of heteroatoms in carbon nanostructures and template synthesis methods, are also reviewed. The effects of other device components, such as electrolyte ion size and solvent system, electrode design and use of binders, to the overall capability of EC, are also discussed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
4.
W.-C. Xu K. Takahashi Y. Matsuo Y. Hattori M. Kumagai S. Ishiyama K. Kaneko S. Iijima 《International Journal of Hydrogen Energy》2007
Hydrogen storage capacity of various carbon materials, including activated carbon (AC), single-walled carbon nanohorn, single-walled carbon nanotubes, and graphitic carbon nanofibers, was investigated at 303 and 77 K, respectively. The results showed that hydrogen storage capacity of carbon materials was less than 1 wt% at 303 K, and a super activated carbon, Maxsorb, had the highest capacity (0.67 wt%). By lowering adsorption temperature to 77 K, hydrogen storage capacity of carbon materials increased significantly and Maxsorb could store a large amount of hydrogen (5.7 wt%) at a relatively low pressure of 3 MPa. Hydrogen storage capacity of carbon materials was proportional to their specific surface area and the volume of micropores, and the narrow micropores was preferred to adsorption of hydrogen, indicating that all carbon materials adsorbed hydrogen gas through physical adsorption on the surface. 相似文献
5.
Lithium-sulfur batteries (LSBs) are among the most promising next generation electrochemical energy storage systems due to their ultrahigh energy density, which has attracted enormous attentions. Nevertheless, the development and application of LSBs are still subject to some major technical obstacles such as the insulating nature of sulfur, the shuttle effect of intermediate polysulfides, and the drastic volume expansion. To overcome these challenges, various strategies have been employed to promote the performance of LSBs. This review focuses on summarizing the major development of novel nanostructured carbon hosts for advanced LSBs. The carbon nanotubes, graphene, and carbon spheres are introduced to improve our understanding of the morphology effects on LSBs. The heterogeneous atom-doping, unique hollow structures are summarized to investigate the chemical bonding effects during the charge/discharge process. The organic framework derived carbon structures are discussed to inspire us to find novel routes to enhance the performance of LSBs. Finally, the conclusions and prospects of nanostructured carbon in LSBs are proposed, while the challenges in the further development of LSBs are also discussed. 相似文献
6.
J.L. Pinilla R. UtrillaR.K. Karn I. SuelvesM.J. Lázaro R. MolinerA.B. García J.N. Rouzaud 《International Journal of Hydrogen Energy》2011,36(13):7832-7843
The production of hydrogen and filamentous carbon by means of methane decomposition was investigated in a fixed-bed reactor using iron-based catalysts. The effect of the textural promoter and the addition of Mo as a dopant affects the catalysts performance substantially: iron catalyst prepared with Al2O3 showed slightly higher catalytic performance as compared to those prepared with MgO; Mo addition was found to improve the catalytic performance of the catalyst prepared with MgO, whereas in the catalyst prepared with Al2O3 displayed similar or slightly poorer results. Additionally, the influence of the catalyst reduction temperature, the reaction temperature and the space velocity on the hydrogen yield was thoroughly investigated. The study reveals that iron catalysts allow achieving high methane conversions at operating temperatures higher than 800 °C, yielding simultaneously carbon nanofilaments with interesting properties. Thus, at 900 °C reaction temperature and 1 l g−1cat h−1 space velocity, ca. 93 vol% hydrogen concentration was obtained, which corresponds to a methane conversion of 87%. Additionally, it was found that at temperatures higher than 700 °C, carbon co-product is deposited mainly as multi walled carbon nanotubes. The textural and structural properties of the carbonaceous structures obtained are also presented. 相似文献
7.
《International Journal of Hydrogen Energy》2020,45(55):30767-30782
The effect of heteroatoms on hydrogen adsorption properties of activated and hybrid carbon materials is critically described. For that purpose, olive stones were activated chemically with KOH, and subsequently washed or not, and oxidised with ozone or not. Olive stones were also activated physically with CO2. A series of activated carbons prepared by chemical activation of sucrose was also investigated for comparison. As a result, many activated carbons with different pore-size distributions, surface areas, average micropore widths, oxygen contents and amounts of mineral matter could be compared. All were thoroughly characterised by adsorption of N2, CO2 and H2O, elemental analysis, XPS, thermogravimetry, and adsorption of H2 at different pressures. Many correlations between textural parameters, composition and adsorption properties could be evidenced, and were critically discussed. We show that the hydrogen uptake at 77 K is controlled by the following parameters, listed by decreasing order of importance: specific surface area, average micropore size, surface chemistry and shape of the pore size distribution. At room temperature (i.e., at 298 K), the adsorbed hydrogen uptake was in the range of 0.19–0.42 wt %; the presence of large amounts of alkali metals can further improve the hydrogen adsorption properties, but surface chemistry still has a major influence, especially through the acidic surface functions. 相似文献
8.
《International Journal of Hydrogen Energy》2019,44(41):23210-23215
In this paper, a common low-cost chemical material-polyacrylonitrile (PAN) is transformed into porous carbon with excellent specific surface area (2564.6–3048.8 m2 g−1) and highly concentrated micropore size distribution (0.7–2.0 nm). Benefit to the unique structure, the as-prepared materials show appealing hydrogen adsorption capacity (4.70–5.94 wt % at 20 bar, 7.15–10.14 wt % at 50 bar), demonstrating a promising prospect of practical application. This work also confirmed that the narrow and deep ultramicropore (<0.7 nm) could facilitate adsorption of hydrogen molecules significantly at atmospheric pressure, and the volume increase of supermicropore (0.7–2.0 nm) could lead to hydrogen capacity promotion at relative high pressure (>20 bar), which provides valuable guidance for the construction of ideal porous adsorbent for efficiency hydrogen storage. 相似文献
9.
Hydrocarbon fossil fuels can be considered as hydrogen ores for CO2-free energy, and carbon ores for carbonaceous construction materials. Hydrogen fuel can be extracted from fossil fuels by decarbonization, and used as an energy resource. The carbon byproduct can be used as a versatile construction material. Carbon materials would sequester carbon, and replace CO2-generating steel and concrete. Approximate comparison of the global consumption of energy and construction materials suggests a rough mass balance of energy and materials markets. The cost of foregoing the carbon energy content as a fuel can be easily offset by the value of the carbon-based construction material. The nature and properties of carbon materials and conventional infrastructural materials are compared. 相似文献
10.
M. ArmandiB. Bonelli K. Cho R. Ryoo E. Garrone 《International Journal of Hydrogen Energy》2011,36(13):7937-7943
Hydrogen adsorption capabilities of different nanoporous carbon, i.e. amorphous carbons obtained by chemical activation (with KOH) of a sucrose-derived char previously ground by ball milling and carbon replicas of NH4-Y and mesocellular silica foam (MSU-F) inorganic templates, were measured and correlated to their porous properties. The porous texture of the prepared carbon materials was studied by means of N2 and CO2 adsorption isotherms measured at −196 °C and 0 °C, respectively. Comparison with nanoporous carbons obtained without pre-grinding the sucrose-derived char [12] shows that the ball milling procedure favours the formation of highly microporous carbon materials even at low KOH loadings, having a beneficial effect of the interaction between the char particles and the activating agent. Hydrogen adsorption isotherms at −196 °C were measured in the 0.0-1.1 MPa pressure range, and a maximum hydrogen adsorption capacity of 3.4 wt.% was obtained for the amorphous carbon prepared by activation at 900 °C with a KOH/char weight ratio of 2. Finally, a linear dependence was found between the maximum hydrogen uptake at 1.1 MPa and the samples microporous volume, confirming previous results obtained at −196 °C and sub-atmospheric pressure [12]. 相似文献
11.
《International Journal of Hydrogen Energy》2020,45(48):25900-25911
Hydrogen storage by spillover in porous carbon material (PCM) has achieved great success in experiments. During the past 20 years, a large number of theoretical works have been performed to explore the hydrogen spillover mechanism, look for high-performance hydrogen storage materials and high-efficiency catalysts. In this paper, we summarize and analyze the results of the past researches, and draw the following conclusions: (1) In PCM surface, the stability of chemisorbed H can be reached through phase nucleation process, which can be initiated in the vicinity of surface impurities or defects. (2) To achieve the 2020 U.S. Department of Energy (DOE) target, the PCM material used for hydrogen storage by spillover should have a sp2 carbon ratio greater than 0.43 and a surface area less than 3500 m2/g, which gives us an inspiration for exploring hydrogen spillover materials. (3) Due to a high barrier, the hydrogen spillover almost can not be initiated on pure PCM substrate at room temperature. By introducing the defects or impurities (e.g. holes, carbon bridges, oxygen functional groups, boron atoms and fluorine atoms), the spillover barriers can be reduced to a reasonable range. In addition, hydrogen atoms may also migrate in a gas phase. (4) According to our previous results of kinetic Monte Carlo simulations, there is a linear relationship between the reaction temperature and the migration barrier. The optimal barrier for the hydrogen spillover should be in the range of 0.60–0.88 eV. (5) Once the hydrogen atoms are chemically adsorbed on the carbon substrate, it is difficult to diffuse again due to the strong strength of C–H bond. Several theoretical diffusion mechanisms have been proposed. For example, the H atoms in physisorption state can diffuse freely on carbon surfaces with high mobility, using the shuttle gases (e.g. BH−4, H2O, HF and NH3) to make the migration thermodynamically possible and decrease the migration barrier, the H atoms diffuse inside the interlayer space of the bi- and tetralayer graphene, and introducing the impurities on the surface to facilitate the hydrogen diffusion. (6) The H desorption through the directly recombination or the reverse spillover is unlikely to occur at normal temperature. The Eley-Rideal reaction may be the only possible mechanism for desorption of the adsorbed H atoms in carbon substrate. Finally, we have made a prospect for further research works on hydrogen storage by spillover. 相似文献
12.
《International Journal of Hydrogen Energy》2019,44(48):26646-26664
With increasing attention on hydrogen (H2) produced by renewable energy methods for transport and other applications, an updated evaluation of H2 monitoring techniques is timely. The emergence of nanomaterials with unique properties enables a new class of H2 sensing materials, exhibiting important attributes such as high surface area to volume ratio, reactivity and number of active sites. The development of these materials allows for improved H2 sensing methods with increased sensitivity, selectivity, speed and improved economy for both financial cost and power consumption. These advances enable small-scale, high-performance H2 sensors for use in emerging hybrid renewable energy systems, including Internet of Things (IoT) or mobile systems. While literature reports on H2 sensors include thermal conductivity, resistive, optical, acoustic, electrochemical and catalytic methods, this review will focus on resistive H2 sensing nanomaterials. Three classes of these nanomaterials are discussed: metal oxides, transition metal dichalcogenides, and graphene based nanomaterials. As a key aim of this review is improved economy of use, we will elaborate only sensors operating at temperatures lower than 200 °C, with a focus on potential for room temperature operation. 相似文献
13.
Philippe Dibandjo Claudia Zlotea Roger Gadiou Camelia Matei Ghimbeu Fermin Cuevas Michel Latroche Eric Leroy Cathie Vix-Guterl 《International Journal of Hydrogen Energy》2013
Hydrogen adsorption on porous materials is one of the possible methods proposed for hydrogen storage for transport applications. One way for increasing adsorption at room temperature is the inclusion of metal nanoparticles to increase hydrogen–surface interactions. In this study, ordered mesoporous carbon materials were synthesized by replication of nanostructured mesoporous SBA-15 silica. The combination of different carbon precursors allowed to tailor the textural, structural and chemical properties of the materials. These carbons were used for the synthesis of hybrid nanostructured carbon/palladium materials with different sizes of metal nanoparticles. The hydrogen sorption isotherms were measured at 77 K and 298 K between 0.1 and 8 MPa. Hydrogen storage capacities strongly correlate with the textural properties of the carbon at 77 K. At room temperature, Pd nanoparticles enhance hydrogen storage capacity by reversible formation of hydride PdHx and through the spillover mechanism. The hydrogen uptake depends on the combined influences of metal particle size and of carbon chemical properties. Carbons obtained from sucrose precursors lead to the hybrid materials with the highest storage capacities since they exhibits a large microporous volume and a high density of oxygenated surface groups. 相似文献
14.
《International Journal of Hydrogen Energy》2020,45(1):337-379
Photocatalytic H2 production is a hopeful technology to solving the environment problems and global energy. Consequently, it is essential to develop high efficient, nonprecious and stable photocatalysts. Graphitic carbon nitride (g-C3N4) was fascinated much concentration owed to this metal free n-type semiconductor possesses appropriate bandgap, unique two dimensional (2D) layered structures, low toxicity, high thermal and chemical stability, lowcost, facile preparation and visible light response. Moreover, the g-C3N4 composites are having huge promise on photocatalytic H2 production but, the efficiency of pure g-C3N4 is at present limited by its poor visible light absorption and suffers from high recombination rate of g-C3N4 photogenerated electron/hole pairs resulting in low photocatalytic performance. Furthermore, the g-C3N4 has unique electronic structure, therefore renowned candidates have been coupled with different functional components to improve photocatalytic activity. In this contribution, we review the recent research progresses of transition metals, non metals, noble metals, semiconductor compounds, graphene, carbon nanotubes (CNTs), carbon dots and quantum dots, supported on g-C3N4 nanosheets, which were applied to photocatalytic H2 production. In addition, different techniques used to synthesis the g-C3N4 based photocatalyst including with their corresponding examples have been described. We hope that this review will encourage the readers to extend the applications of g-C3N4 based heterostructure in the field of H2 production in a green manner. 相似文献
15.
Fossil fuels can be considered as hydrogen ores for CO2-free energy, and carbon ores for carbon construction materials. This paper discusses methods for extraction of hydrogen from fossil fuels without carbon oxidation, with co-production of high value solid carbon material products. 相似文献
16.
《International Journal of Hydrogen Energy》2020,45(17):10516-10522
We investigate the use of carbonized bamboo, which has an organic porous structure, as a hydrogen storage material. Bamboo samples were thermally treated at 800, 900, 1000, and 1100 °C for 24 h. The pore size and hydrogen storage capacity of each sample were measured by N2 and H2 gas sorption up to 1.13 bar at 77 K. The maximum hydrogen storage was exhibited by the sample treated at 900 °C, which reached 1.35 wt% at 1.13 bar/77 K. The results showed that the bamboo, one of the green carbons, has the potential to be used as an environmental-friendly carbon backbone for hybrid hydrogen storage materials. 相似文献
17.
Rohit R. Shahi Himanshu RaghubanshiM.A. Shaz O.N. Srivastava 《International Journal of Hydrogen Energy》2013
The effect of different carbon nanostructures specifically carbon nanotubes (CNTs) and carbon nanofibers (CNFs) on the improvement of the de/re-hydrogenation characteristics of a Mg(NH2)2/LiH mixture have been studied. Amongst CNTs and CNFs, the improvement in the hydrogenation properties for the Mg(NH2)2/LiH mixture is higher when CNFs are used as a catalyst. Investigations are also focused on the deployment of two different types of CNF (a) CNF1 (synthesized using a ZrFe2 catalyst) and (b) CNF2 (synthesized using a LaNi5 catalyst). The results show that CNF2 is better. The maximum decomposition temperature for the pristine Mg(NH2)2/LiH mixture is found to be ∼250 °C, which is reduced to ∼180 and ∼150 °C for the sample mixed with 4 wt% of multi-walled carbon nanotubes (MWCNTs) and CNF2 respectively. The activation energy for the dehydrogenation reaction is found to be 74 and 68 kJ mol−1 for the samples mixed with MWCNT and CNF2 respectively, whereas the activation energy for the dehydrogenation reaction of the pristine Mg(NH2)2/LiH mixture is 97 kJ mol−1. The catalytic activity and the de/re-hydrogenation characteristics of the Mg(NH2)2/LiH mixture mixed with different carbon nanostructures are described and discussed. 相似文献
18.
19.
Ningning Liu Longwei YinLe Kang Xinyu ZhaoChengxiang Wang Luyuan ZhangDong Xiang Rui GaoYongxin Qi Ning Lun 《International Journal of Hydrogen Energy》2010
Electrochemical properties of activated ordered mesoporous carbon (OMC) containing nickel inclusions are investigated using cyclic voltammetry and galvanostatic charge/discharge techniques. The hard-template-route prepared OMC is of structurally well-ordered two-dimensional hexagonal structure with a high specific surface area of 1896.95 cm2 g−1, a pore volume of 1.781 cm3 g−1 and a pore size of 5.1 nm, respectively. It is shown that OMC/0.3Ni electrode displays the highest specific capacitance of 186.1 Fg−1, almost 1.4 times higher than that of pure OMC electrode. The hydrogen storage capacity of pure OMC electrode is 87 mAh g−1 and there exists no discharge platform. With the amount of nickel addition increasing, there appears a relatively stable discharge platform, and the discharge capacity reaches a maximum of 170 mAh g−1 as the molar ratio of Ni:OMC is 0.3, almost two times higher than that of pure OMC electrode. The electrochemical properties of OMC can be greatly improved with incorporation of nickel powders. The Ni activated OMC electrodes display a high capacity retainability with strong resistance against oxidation and corrosion. 相似文献
20.
《International Journal of Hydrogen Energy》2022,47(11):7202-7213
The coupling of two-dimensional (2D) layered materials is an effective way to realize photocatalytic hydrogen production. Herein, using first-principles calculations, the photocatalytic properties of GaN/CNs heterojunctions formed by two different graphite-like carbon nitride materials and GaN monolayer are discussed in detail. The results show that the GaN/C2N heterojunction can promote the effective separation of photogenerated electron and hole pairs, which is attributed to its type-II band orientation and high carrier mobility. However, the low overpotential of GaN/C2N for photocatalytic hydrogen production limits the photocatalytic performance. On this basis, we adjust the CBM position of the GaN/C2N heterojunction by applying an electric field to enhance its hydrogen evolution capability. In addition, the GaN/g-C3N4 is a type-I heterojunction, which is suitable for the field of optoelectronic devices. This work broadens the field of vision for the preparation of highly efficient photocatalysts. 相似文献