共查询到20条相似文献,搜索用时 15 毫秒
1.
Dalia Angeles-Wedler Katrin Mackenzie Frank-Dieter Kopinke 《Applied catalysis. B, Environmental》2009,90(3-4):613-617
Pd-based catalysts have become important in environmental catalysis for their ability to hydrodechlorinate a wide range of chlorinated organic contaminants in water under ambient conditions. The success of their application in the remediation practice, e.g. for groundwater treatment, is often hindered by the sensitivity of Pd to poisoning by sulphur compounds. In this study, the stability and sulphide-induced deactivation behaviour of a highly active Pd/Al2O3 catalyst was investigated. The specific activity of Pd for the hydrodechlorination of chlorobenzene corresponds to rate coefficients up to kPd = 350 L g−1 min−1. The totally deactivated catalyst, resultant of sulphide poisoning, was regenerated with potassium permanganate. The pH value, as a key parameter which may influence the degree of deactivation as well as the efficiency of catalyst regeneration, was evaluated. Results show that in clean water the Pd/Al2O3 catalyst showed no inherent deactivation regardless of the ageing time and the pH value of the catalyst suspension. The degree of catalyst poisoning effected by 1.8–5.4 μM sulphide, corresponding to molar ratios of S:Pdsurface = 1.5–8.5, was observed to be higher under neutral and alkaline than under acidic conditions. The exposure of the catalyst to higher sulphide concentration of 14.2 μM resulted in complete catalyst deactivation regardless of the pH conditions. However, the efficacy of permanganate as oxidative regenerant for the fouled catalyst showed strong pH-dependence. A regeneration time of 10–30 min at low pH was sufficient to recover completely the high catalytic activity of Pd/Al2O3 for the hydrodechlorination reaction. 相似文献
2.
Laurent Piccolo Helen Daly Ana Valcarcel Frdric C. Meunier 《Applied catalysis. B, Environmental》2009,86(3-4):190-195
The oxidation of carbon monoxide in the presence of various concentrations of molecular hydrogen has been studied over a Au/TiO2 reference catalyst by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectrometry. It is shown for the first time that H2 enhances the CO oxidation rate on Au/TiO2 without leading to any major loss of selectivity. Increasing the H2 pressure induces higher CO and H2 oxidation rates. Under H2-free conditions, the surface species detected are Auδ+–CO, Ti4+–CO, carbon dioxide and carbonates. Upon the addition of H2, Au0–CO, water and hydroxyl groups become the main surface species. The occurrence of a preferential CO oxidation mechanism involving HxOy species under the present experimental conditions is proposed. 相似文献
3.
Ceria supported 2 wt% Pd catalysts for low-temperature methane combustion were prepared by the impregnation (IM) and deposition–precipitation (DP) methods, which are denoted as Pd–IM and Pd–DP, respectively. DP was found to be an available method for achieving high activity and stability of the Pd/CeO2 catalyst. The temperatures for methane ignition (T10%) and total conversion (T100%) over Pd–DP are 224 and 300 °C at GHSV of 50,000 h−1, which are 83 and 110 °C lower than the corresponding temperatures of Pd/Al2O3. X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) analyses show that palladium species in Pd–DP is highly dispersed, positively charged and difficultly reduced. Raman spectra disclosed that the largest concentration of defects and/or oxygen vacancies was formed in Pd–DP catalyst. A kind of cationic PdOδ+ sites with higher binding energies than PdO are in close vicinity to the oxygen vacancies in the CeO2 support and might act as the active centers for methane oxidation. Furthermore, the deactivation and steam aging tests for Pd–DP showed that the performance of this type of palladium was very stable and could be repeatedly recovered after several long time aging tests. 相似文献
4.
Copper metallic foam with thermal conductive properties, manufactured by S.C.P.S., has been investigated as a support for catalysts to improve thermal exchange inside the reactor for the endothermic steam reforming of methanol. Thus, we have developed a procedure for the in situ preparation of a Cu0–ZnII/Al2O3 catalyst onto the copper metallic foam. The foam-based Cu0–ZnII/Al2O3 catalyst shows an activity three times as high as commercial catalysts for a conversion of 74% of methanol into hydrogen. 相似文献
5.
The structure of a methylamine sorption complex of fully dehydrated, fully Cd2+-exchanged zeolite X, Cd46(CH3NH2)16[Si100Al92O384]-FAU (a = 24.863(4) Å), has been determined by single-crystal X-ray diffraction techniques in the cubic space group at 21(1) °C. An aqueous exchange solution 0.05 M in Cd2+ was allowed to flow past the crystal for 5 days. The crystal was then dehydrated at 480 °C and 2 × 10−6 Torr for 2 days (colorless), and exposed to 160 Torr of methylamine gas at 21(1) °C for 2 h (yellow). Diffraction data were then gathered in this atmosphere and were refined using all data to the final error indices (based upon the 524 reflections for which Fo > 4σ(Fo)) of R1 = 0.069 and wR2 = 0.200. In this structure, Cd2+ ions occupy three crystallographic sites. The octahedral sites I at the centers of the hexagonal prisms are filled with 16 Cd2+ ions per unit cell (Cd–O = 2.369(8) Å). The remaining 30 Cd2+ ions are located at two non-equivalent sites II with occupancies of 14 and 16. The 16 methylamine molecules per unit cell lie in the supercage where each interacts with one of the latter 16 site-II Cd2+ ions: N–Cd = 2.11(8) Å. The imprecisely determined N–C bond length, 1.49(22) Å, agrees with that in gaseous methylamine, 1.474 Å. The positions of the hydrogen atoms were calculated. It appears that one of the amino hydrogen atoms hydrogen bonds to a 6-ring oxygen, and that the other forms a bifurcated hydrogen bond to this and another 6-ring oxygen. The methyl group is not involved in hydrogen bonding. 相似文献
6.
Benjaram M. Reddy Seung-Cheol Lee Dae-Soo Han Sang-Eon Park 《Applied catalysis. B, Environmental》2009,87(3-4):230-238
Vanadium oxide and cerium oxide doped titania–zirconia mixed oxides were explored for oxidative dehydrogenation of ethylbenzene to styrene utilizing carbon dioxide as a soft oxidant. The investigated TiO2–ZrO2 mixed oxide support with high specific surface area (207 m2 g−1) was synthesized by a coprecipitation method. Over the calcined support (550 °C), a monolayer equivalent (15 wt.%) of V2O5, CeO2 or a combination of both were deposited by using wet-impregnation or co-impregnation methods to make the V2O5/TiO2–ZrO2, CeO2/TiO2–ZrO2 and V2O5–CeO2/TiO2–ZrO2 combination catalysts, respectively. These catalysts were characterized using X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature preprogrammed reduction (TPR), CO2 temperature preprogrammed desorption (TPD) and BET surface area methods. All characterization studies revealed that the deposited promoter oxides are in a highly dispersed form over the support, and the combined acid–base and redox properties of the catalysts play a major role in this reaction. The V2O5–CeO2/TiO2–ZrO2 catalyst exhibited a better conversion and product selectivity than other combinations. In particular, the addition of CeO2 to V2O5/TiO2–ZrO2 prevented catalyst deactivation and helped to maintain a high and stable catalytic activity. 相似文献
7.
The rate of Fischer–Tropsch synthesis over an industrial well-characterized Co–Ru/γ-Al2O3 catalyst was studied in a laboratory well mixed, continuous flow, slurry reactor under the conditions relevant to industrial operations as follows: temperature of 200–240 °C, pressure of 20–35 bar, H2/CO feed ratio of 1.0–2.5, gas hourly space velocity of 500–1500 N cm3 gcat− 1 h− 1 and conversions of 10–84% of carbon monoxide and 13–89% of hydrogen. The ranges of partial pressures of CO and H2 have been chosen as 5–15 and 10–25 bar respectively. Five kinetic models are considered: one empirical power law model and four variations of the Langmuir–Hinshelwood–Hougen–Watson representation. All models considered incorporate a strong inhibition due to CO adsorption. The data of this study are fitted fairly well by a simple LHHW form − RH2 + CO = apH20.988pCO0.508 / (1 + bpCO0.508)2 in comparison to fits of the same data by several other representative LHHW rate forms proposed in other works. The apparent activation energy was 94–103 kJ/mol. Kinetic parameters are determined using the genetic algorithm approach (GA), followed by the Levenberg–Marquardt (LM) method to make refined optimization, and are validated by means of statistical analysis. Also, the performance of the catalyst for Fischer–Tropsch synthesis and the hydrocarbon product distributions were investigated under different reaction conditions. 相似文献
8.
J. McGregor Z. Huang G. Shiko L.F. Gladden R.S. Stein M.J. Duer Z. Wu P.C. Stair S. Rugmini S.D. Jackson 《Catalysis Today》2009,142(3-4):143
A series of θ-Al2O3 supported VOx catalysts, of different vanadium loadings, have been characterised and employed for the selective dehydrogenation of n-butane. Characterisation of the unreacted catalysts has been carried out by solid-state NMR (51V MAS NMR, 27Al MAS NMR and 27Al 3Q-MAS NMR), and FT-IR spectroscopies, with reference to previously acquired Raman and UV–vis spectroscopy data. As vanadium loading increases, so does the domain size of the supported vanadate units with significant quantities of V2O5 observed at the highest loadings. The influence of calcination, pre-reduction, reaction and regeneration on the structure of the catalysts has been studied by NMR, FT-IR, EPR, microanalysis and TEOM. Calcination disperses crystalline vanadate units, and at high loadings AlVO4 formation is observed. Pre-reduction reduces the vanadium oxidation state from 5+ to 3+, while regeneration results in the formation of highly crystalline V5+ species. From these data it is possible to determine structure–activity relationships, with polymeric vanadia clusters favouring the formation of butenes and butadienes, while more isolated species are highly active towards the formation of polynuclear aromatic hydrocarbons retained on the catalyst surface post-reaction. These large polynuclear aromatic hydrocarbons are however not the principle cause of catalyst deactivation in this reaction. 相似文献
9.
K. Aït-Lachgar-Ben Abdelouahad M. Roullet M. Brun A. Burrows C. J. Kiely J. C. Volta M. Abon 《Applied Catalysis A: General》2001,210(1-2)
The catalytic properties of (VO)2P2O7/α-Sb2O4 mixed oxides system for n-butane mild oxidation have been investigated on two mechanical mixtures (M1 and M2) of the same well crystallized (VO)2P2O7 (reference vanadyl pyrophosphate) with two different morphologies of α-Sb2O4.The M1 mixture of (VO)2P2O7 with α-Sb2O4 (1), prepared by oxidation of Sb2O3, leads to the oxidative dehydrogenation (ODH) of n-butane, whereas the M2 mixture of (VO)2P2O7 with a commercial α-Sb2O4 (2) (Aldrich) with a different morphology improves the maleic anhydride selectivity as compared to the reference (VO)2P2O7 catalyst (synergetic effect). After reaction, no ternary VPSbO phase is detected by XRD and DTA and it was controlled that the two α-Sb2O4 oxides are catalytically inactive.The (VO)2P2O7 reference catalyst which produced only maleic anhydride as mild oxidation product shows by XPS a slightly oxidized surface (14% V5+–86% V4+).Contamination of the (VO)2P2O7 phase by migration of Sb species occurs after catalytic reaction in the case of the M1 mixture as shown by XPS, LEIS and TEM–EDX analysis. XPS showed that (VO)2P2O7 is partially superficially reduced (86% V4+–14% V3+). This feature is consistent with the decrease of acidity as observed by pyridine adsorption–desorption.In opposition with the M1 mixture, no contamination of the (VO)2P2O7 phase is observed after catalytic reaction in the case of the M2 mixture. The XPS study shows, in this case, that (VO)2P2O7 is partially oxidized (30% V5+–70% V4+) at a higher level than for the reference (VO)2P2O7 catalyst. This situation is associated with the increase of selectivity observed for maleic anhydride (synergetic effect).The difference in the catalytic results for the two M1 and M2 mixtures, as compared to the (VO)2P2O7 reference catalyst, can be explained by the alteration of the surface composition of (VO)2P2O7 and the distribution of vanadium oxidation state due to different interaction between Sb2O4and (VO)2P2O7, depending on the orientation of the α-Sb2O4 crystals. 相似文献
10.
CeO2–TiO2 (Ce:Ti = 0.25–9, molar ratio) catalysts were synthesized by a sol–gel method and the catalytic performances were evaluated in the selective synthesis of isobutene and isobutane from CO hydrogenation under the reaction conditions of 673–748 K, 1–5 MPa and 720–3000 h−1. The physical properties, such as specific surface area, cumulative pore volume, average pore diameter, crystal phase and size, of the catalysts were characterized by N2 adsorption/desorption and XRD. All the CeO2–TiO2 composite oxides showed higher surface areas than pure TiO2 and CeO2. No TiO2 phase was detected on the samples of CeO2–TiO2 in which TiO2 contents were in the range of 10–50 mol%. Crystalline Ce2O3 was detected in CeO2–TiO2 (8:2). The reaction conditions, temperature, pressure and space velocity, had obvious influences on the CO conversion and distribution of the products over CeO2–TiO2 (8:2) catalyst. 相似文献
11.
Solid superacid catalysts including SO42−/ZrO2 (SZ), rare earth (RE) oxide-promoted SZ and RE oxides together with alumina-promoted SZ were prepared. Their catalytic performances in the esterification reaction of ethanol and acetic acid were investigated. The textural property, crystalline phase and surface acidity of the prepared catalysts were characterized by using nitrogen adsorption–desorption isotherms, X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy of pyridine adsorption techniques, respectively. Effects of the reaction time and catalyst reuse cycle as well as catalyst regeneration on the catalytic behaviors were studied. Experimental results showed that Yb2O3–Al2O3 promoted SZ (designated as SZAY) catalyst exhibited an optimal esterification performance; the Lewis acid sites with moderate and super strong strength could mainly be responsible for the esterification reaction; and doping both Yb2O3 and Al2O3 on SZ not only boosted the esterification activity but also alleviated catalyst deactivation resulted from the surface sulfur loss by solvation. 相似文献
12.
Jorge D.A. Bellido Eurico Y. Tanabe Elisabete M. Assaf 《Applied catalysis. B, Environmental》2009,90(3-4):485-488
Supported nickel catalysts of composition Ni/Y2O3–ZrO2 were synthesized in one step by the polymerization method and compared with a nickel catalyst prepared by wet impregnation. Stronger interactions were observed in the formed catalysts between NiO species and the oxygen vacancies of the Y2O3–ZrO2 in the catalysts made by polymerization, and these were attributed to less agglomeration of the NiO during the synthesis of the catalysts in one step. The dry reforming of ethanol was catalyzed with a maximum CO2 conversion of 61% on the 5NiYZ catalyst at 800 °C, representing a better response than for the catalyst of the same composition prepared by wet impregnation. 相似文献
13.
MnOx–CeO2 mixed oxide catalysts prepared by sol–gel method were tested for the catalytic combustion of chlorobenzene (CB), as a model of chlorinated aromatic volatile organic compounds (CVOCs). MnOx–CeO2 catalysts with the different ratio of Mn/Ce + Mn were found to possess high catalytic activity for catalytic combustion of CB, and MnOx(0.86)–CeO2 was the most active catalyst, on which the complete combustion temperature (T90%) of chlorobenzene was 236 °C. The stability of MnOx–CeO2 catalysts in the CB combustion was investigated. MnOx–CeO2 catalysts with high Mn/Ce + Mn ratios present high stable activity, which is related to their high ability to remove Cl species adsorbed and a large amount of active surface oxygen. 相似文献
14.
Xue-Lian Liang Xin Dong Guo-Dong Lin Hong-Bin Zhang 《Applied catalysis. B, Environmental》2009,88(3-4):315-322
A type of Pd–ZnO catalysts supported on multi-walled carbon nanotubes (MWCNTs) were developed, with excellent performance for CO2 hydrogenation to methanol. Under reaction conditions of 3.0 MPa and 523 K, the observed turnover-frequency of CO2 hydrogenation reached 1.15 × 10−2 s−1 over the 16%Pd0.1Zn1/CNTs(h-type). This value was 1.17 and 1.18 times that (0.98 × 10−2 and 0.97 × 10−2 s−1) of the 35%Pd0.1Zn1/AC and 20%Pd0.1Zn1/γ-Al2O3 catalysts with the respective optimal Pd0.1Zn1-loading. Using the MWCNTs in place of AC or γ-Al2O3 as the catalyst support displayed little change in the apparent activation energy for the CO2 hydrogenation, but led to an increase of surface concentration of the Pd0-species in the form of PdZn alloys, a kind of catalytically active Pd0-species closely associated with the methanol generation. On the other hand, the MWCNT-supported Pd–ZnO catalyst could reversibly adsorb a greater amount of hydrogen at temperatures ranging from room temperature to 623 K. This unique feature would help to generate a micro-environment with higher concentration of active H-adspecies at the surface of the functioning catalyst, thus increasing the rate of surface hydrogenation reactions. In comparison with the “Parallel-type (p-type)” MWCNTs, the “Herringbone-type (h-type)” MWCNTs possess more active surface (with more dangling bonds), and thus, higher capacity for adsorbing H2, which make their promoting action more remarkable. 相似文献
15.
Electrical conductivity measurements on EUROCAT V2O5–WO3/TiO2 catalyst and on its precursor without vanadia were performed at 300°C under pure oxygen to characterize the samples, under NO and under NH3 to determine the mode of reactivity of these reactants and under two reaction mixtures ((i) 2000 ppm NO + 2000 ppm NH3 without O2, and (ii) 2000 ppm NO + 2000 ppm NH3 + 500 ppm O2) to put in evidence redox processes in SCR deNOx reaction.It was first demonstrated that titania support contains certain amounts of dissolved W6+ and V5+ ions, whose dissolution in the lattice of titania creates an n-type doping effect. Electrical conductivity revealed that the so-called reference pure titania monolith was highly doped by heterovalent cations whose valency was higher than +4. Subsequent chemical analyses revealed that so-called pure titania reference catalyst was actually the WO3/TiO2 precursor of V2O5–WO3/TiO2 EUROCAT catalyst. It contained an average amount of 0.37 at.% W6+dissolved in titania, i.e. 1.07 × 1020 W6+ cations dissolved/cm3 of titania. For the fresh catalyst, the mean amounts of W6+ and V5+ ions dissolved in titania were found to be equal to 1.07 × 1020 and 4.47 × 1020 cm−3, respectively. For the used catalyst, the mean amounts of W6+ and V5+ ions dissolved were found to be equal to 1.07 × 1020 and 7.42 × 1020 cm−3, respectively. Since fresh and used catalysts have similar compositions and similar catalytic behaviours, the only manifestation of ageing was a supplementary progressive dissolution of 2.9 × 1020 additional V5+ cations in titania.After a prompt removal of oxygen, it appeared that NO alone has an electron acceptor character, linked to its possible ionosorption as NO− and to the filling of anionic vacancies, mostly present on vanadia. Ammonia had a strong reducing behaviour with the formation of singly ionized vacancies. A subsequent introduction of NO indicated a donor character of this molecule, in opposition to its first adsorption. This was ascribed to its reaction with previously adsorbed ammonia strongly bound to acidic sites. Under NO + NH3 reaction mixture in the absence of oxygen, the increase of electrical conductivity was ascribed to the formation of anionic vacancies, mainly on vanadia, created by dehydroxylation and dehydration of the surface. These anionic vacancies were initially subsequently filled by the oxygen atom of NO. No atoms, resulting from the dissociation of NO and from ammonia dehydrogenation, recombined into dinitrogen molecules. The reaction corresponded to
. In the presence of oxygen, NO did not exhibit anymore its electron acceptor character, since the filling of anionic vacancies was performed by oxygen from the gas phase. NO reacted directly with ammonia strongly bound on acidic sites. A tentative redox mechanism was proposed for both cases. 相似文献
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16.
K. Rida A. Benabbas F. Bouremmad M.A. Pea A. Martínez-Arias 《Catalysis communications》2006,7(12):963-968
Catalytic CO oxidation and C3H6 combustion have been studied over La1−xSrxCrO3 (x = 0.0–0.3) oxides prepared by solid-state reaction and characterised by X-ray diffraction (XRD), nitrogen adsorption (BET analysis) and X-ray photoelectron spectroscopy (XPS). The expected orthorhombic perovskite structure of the chromite is observed for all levels of substitution. However, surface segregation of strontium along with a chromium oxidation process, leading to formation of Cr6+-containing phases, is produced upon increasing x and shown to be detrimental to the catalytic activity. Maximum activity is achieved for the catalyst with x = 0.1 in which mixed oxide formation upon substitution of lanthanum by strontium in the chromite becomes maximised. 相似文献
17.
Yong Liu Ming Meng Xin-Gang Li Li-Hong Guo Yu-Qing Zha 《Chemical Engineering Research and Design》2008,86(8):932-940
The NOx storage and reduction (NSR) catalysts Pt/K/TiO2–ZrO2 were prepared by an impregnation method. The techniques of XRD, NH3-TPD, CO2-TPD, H2-TPR and in situDRIFTS were employed to investigate their NOx storage behavior and sulfur-resisting performance. It is revealed that the storage capacity and sulfur-resisting ability of these catalysts depend strongly on the calcination temperature of the support. The catalyst with theist support calcined at 500 °C, exhibits the largest specific surface area but the lowest storage capacity. With increasing calcination temperature, the NOx storage capacity of the catalyst improves greatly, but the sulfur-resisting ability of the catalyst decreases. In situ DRIFTS results show that free nitrate species and bulk sulfates are the main storage and sulfation species, respectively, for all the catalysts studied. The CO2-TPD results indicate that the decomposition performance of K2CO3 is largely determined by the surface property of the TiO2–ZrO2 support. The interaction between the surface hydroxyl of the support and K2CO3 promotes the decomposition of K2CO3 to form –OK groups bound to the support, leading to low NOx storage capacity but high sulfur-resisting ability, while the interaction between the highly dispersed K2CO3 species and Lewis acid sites gives rise to high NOx storage capacity but decreased sulfur-resisting ability. The optimal calcination temperature of TiO2–ZrO2 support is 650 °C. 相似文献
18.
Junhua Li Woo Huang Goh Xuechang Yang Ralph T. Yang 《Applied catalysis. B, Environmental》2009,90(3-4):360-367
NOx storage performances have been investigated on a Pt/Ba/Al2O3 catalyst by comparison using two types of non-thermal plasma (NTP) reactor: the “PDC system” reactor and the “PFC system” reactor. In the PDC system, the catalyst was placed in the discharge space and was activated by the plasma directly, whereas in the PFC system, the plasma reactor was followed by the catalyst. The results showed that the NOx storage capacity (NSC) of the Pt/Ba/Al2O3 catalyst was significantly enhanced by the non-thermal plasma in the PDC and PFC system, and the PDC system exhibited better promotional effect than the PFC system in the temperature range of 100–300 °C. The NSC of the catalyst was increased with the increase of the input energy density both in the PDC and PFC system due to the higher NO oxidation at higher input energy density. It was also found that the ionic wind induced by plasma in the PDC system enhanced the quantity of the NO adsorbed onto the catalyst surface and therefore could react with the O-radical to form more NO2, and thus promote the formation of nitrate on the catalyst. 相似文献
19.
Zhanghuai Suo Chunyan Ma Mingshan Jin Tao He Lidun An 《Catalysis communications》2008,9(13):2187-2190
Au–Pd/Al2O3 catalyst was prepared by modified impregnation method. It was found that the catalyst calcined in air at 473 K showed higher CO oxidation activity in comparison with the catalysts treated at other temperature. Nitrogen adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure spectroscopy (XANES) techniques were employed to study the relationship between the surface/bulk structures of these catalysts and their catalytic performance. The results indicated the higher activity was attributed to the smaller pore volume and co-existence of PdO and Au0 in their surface. The formation of AuxPdy alloy was unfavorable for the catalytic reaction. 相似文献
20.
LiFePO4/carbon composite was synthesized at 600 °C for 4 h in an Ar atmosphere by a stearic acid assisted rheological phase method using amorphous nano-FePO4 as the iron source. XRD, SEM and TEM observations show that the LiFePO4/carbon composite has good crystallinity, ultrafine and well-dispersed particles of 60–150 nm size and in situ carbon coated on the surface of LiFePO4 crystallites. The synthesized LiFePO4/carbon composite shows a high discharge capacity of 160 mAh g−1 and 155 mAh g−1 at rates of 0.5 C and 1 C, respectively. Even at a high current density of 30 C, the material still presents a discharge capacity of 93 mAh g−1 and exhibits an excellent cycling performance. 相似文献