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1.
A nanostructured NiSn alloy/multi-walled carbon nanotube (MWCNT) composite was successfully synthesized for highly reversible sodium and hydrogen ions storage by using an electrochemical deposition process on porous Cu foam. The surface morphology of the resulting NiSn alloy/MWCNT nanocomposite was characterized using a field-emission scanning electron microscope, indicating the formation of sphere-like NiSn alloy nanoparticles with an average size of 190 nm. On the other hand, X-ray diffraction analysis, energy dispersive and Fourier transform infrared spectroscopies were employed to determine the crystalline structure, elemental surface and chemical composition of the nanocomposite electrode. The initial sodium discharge capacity of the electrode was maximized at ∼550 mAh g−1 under the current density of 1000 mA g−1, and a high hydrogen discharge capacity of 5200 mAh g−1 was obtained at 1100 mA g−1 after 20 cycles. A comprehensive comparison between the sodium and hydrogen ions capacities in this study and those of the literature for different materials and structures was also performed. Accordingly, the resulting nanocomposite electrode with dual capacity may offer promising applications in both sodium-ion battery and hydrogen storage.  相似文献   

2.
Designing and synthesizing of efficient and inexpensive bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is one of the current research topics. In this study, NiFeCMo film in nickel mesh substrate is prepared by one-step direct-current electrodeposition method. The obtained NiFeCMo film shows the excellent electrocatalytic activity, which only requires overpotentials of 254 mV for HER and 256 mV for OER to drive current density of 10 mA cm−2, with corresponding Tafel slopes of 163.9 and 60.3 mV·dec−1 in 30% KOH medium, respectively. Moreover, NiFeCMo film only needs a low cell voltage of 1.61 V to drive current density of 10 mA cm−2 in an alkaline electrolyzer. Such remarkably HER and OER properties of NiFeCMo alloy is attributed to the increased effective electrochemically active surface area and the synergy effect among Ni, Fe, C and Mo.  相似文献   

3.
Pt/CeMgAl layered double hydroxides with different Ce contents were prepared by one-step co-precipitation method, which underwent calcination and reduction with hydrogen and were finally converted into Pt/CeMgAlO catalysts. These catalysts were tested in the dehydrogenation of methylcyclohexane (MCH) into toluene to produce hydrogen. The addition of CeO2 promoted the dispersion of Pt and decreased the Pt particle size. During the dehydrogenation reaction, toluene was the only liquid product and its selectivity was higher than 99.9%. MCH conversion increased with the reaction temperature rising. The conversion and hydrogen evolution rate on Pt/Ce14MgAlO350 reached up to 98.5% and 1358.6 mmol/gPt/min at 350 °C. Moreover, Pt/CeMgAlO catalysts exhibited no acidity and presented a high anti-coking ability and good stability. These results suggest that Pt/CeMgAlO catalysts have potential industrial application for hydrogen energy utilization.  相似文献   

4.
An effect of Mn content in nanocrystalline TiVMn alloy on hydrogenation properties has been investigated systematically in this work. Ti0.5V1.5-xMnx (x = 0, 0.1, 0.2, 0.3) alloys are synthesized by mechanical alloying method. It has been shown that all alloys need to be activated in order to present the best hydrogenation properties. With increasing Mn content in TiVMn alloys, the maximum hydrogen storage capacity at room temperature firstly increases to reach 3.07 wt% for Ti0.5V1.4Mn0.1 alloy and then gradually decreases. Reversibility of hydriding-dehydriding process improves after chemical modification of TiV alloy. Hydrogen storage properties result from phase composition and structure of alloys. All samples are composed of a major body-centered-cubic (BCC) phase. In Mn-containing materials also a second BCC phase has been detected. Its abundance increases with higher content of Mn in the alloy. Moreover, with increasing Mn content, the lattice parameters of both phases decrease.  相似文献   

5.
PdAgFe, FePdAg and FeAgPd trimetallic nanoparticles were synthesized by seedless and step-wise simultaneous chemical reduction of Fe3+, Ag+ and Pd2+ by using hydrazine in presence of cetyltrimethylammonium bromide and used as a catalyst for the degradation of formic acid. The effects of nanoparticle composition, presence of sodium format (promoter), [catalyst], [formic acid] and temperature play key roles in the hydrogen generation. The Ba(OH)2 trap experiment and water displacement technique were used to determine the generation of CO2 and H2, respectively. The decomposition of formic acid followed complex-order kinetics with respect to [formic acid]. It was found that FeAgPd showed a maximum catalytic activity (turn over frequency) of 75 mol H2 per mol catalyst per h. The activation energy (Ea = 51.6 kJ/mol), activation enthalpy (ΔH = 48.9 kJ/mol) and activation entropy (ΔS = −151.0 JK-1 mol−1) were determined and discussed for the catalytic reaction. The reusability of the FeAgPd at 50 °C shows an efficient degree of activity for six consecutive catalytic cycles.  相似文献   

6.
Ultra-thin proton-conducting phosphate glass was fabricated by press-forming at high temperature. The glass was evaluated for its ohmic loss reduction when installed as an electrolyte in intermediate-temperature fuel cells. The 36HO1/24NbO5/22BaO4LaO3/24GeO21BO3/249PO5/2 glass (36H-glass) was prepared by alkali-proton substitution. Herein, 3–4 mg of 36H-glass was placed onto a 50 μm-thick stainless steel or Pd support and then sandwiched by a glassy carbon plate, whereupon a 600 kg load was applied at temperatures varying as 333–391 °C. Ultra-thin 36H-glass with a thickness of 16 μm was successfully obtained without degradation of proton conductivity. A fuel cell incorporating the Pd-supported ultra-thin 36H-glass was successfully operated at 300 °C, and the ohmic loss of the fuel cell was reduced down to 2.7 Ω cm2 from the previous reported value of several tens of Ω·cm2.  相似文献   

7.
With the aid of computer simulation, we have designed four covalent-organic frameworks based on tetrakis(4-aminophenyl)silsesquioxane (taps-COFs) and their hydrogen storage properties were predicted with grand canonical Monte Carlo (GCMC) simulation. The structural parameters and physical properties were investigated after the geometrical optimization. The accessible surface for H2 molecule (5564.68–6754.78 m2/g) were estimated using the numerical Monte Carlo integration and the pore volume (4.06–10.74 cm3/g) was evaluated by the amounts of the containable nonadsorbing helium molecules at low pressures and room temperature. GCMC simulation reveals that at 77 K, tapsCOF1 has the highest gravimetric H2 adsorption capacity of 51.43 wt% and tapsCOF3 possesses the highest volumetric H2 adsorption capacity of 58.51 g/L. Excitedly, at room temperature of 298 K, the gravimetric hydrogen adsorption capacities of tapsCOF1 (8.58 wt%) and tapsCOF2 (8.20 wt%) have exceeded the target (5.5 wt%) of onboard hydrogen storage system for 2025 set by the U.S Department of Energy.  相似文献   

8.
It is attractive to design and develop a low-cost and environment friendly material preparation route for the catalysts used in alkaline hydrogen evolution reaction. Mineral reconstruction in chlorination roasting and electrodeposition in deep eutectic solvent have been combined in this work. The electrodeposition of NiMoCu coatings from roasted nickel matte precursor in choline chloride (ChCl)-urea deep eutectic solvent (DES) has been investigated. Cyclic voltammetry (CV) implies that the electrodeposition process of NiMoCu coatings in ChCl-urea DES consists of a one-step reaction of Ni(II), a two-step reaction of Cu(II) and Ni/Mo inductive co-deposition. The hydrogen evolution performance parameters of deposited NiMoCu coatings have been systematically studied in alkaline solution by linear sweep voltammetry (LSV), and the electrochemical surface area (ECSA) has been tested by CV. The hydrogen evolution kinetics of deposited NiMoCu coatings has been further investigated by electrochemical impedance spectroscopy (EIS). Owing to its high electrochemical surface area, the NiMoCu coating deposited on Ni foam at −1.2 V can deliver a current density of 10 mA cm−2 at an overpotential of 93 mV in 1 M KOH. It is suggested that NiMoCu coating can be a promising candidate for water splitting in alkaline solution.  相似文献   

9.
The PdZnO/C catalytic material for ethanol oxidation reaction is prepared by microwave heating-glycol reduction method. PdZnO is well polymerized and dispersed on XC72. The results demonstrate that PdZnO/C has better electro catalytic activity and stability for ethanol oxidation reaction than Pd/C at room temperature. ZnO/C shows no catalysis for ethanol oxidation. The oxidation peak potential of PdZnO/C electrode is shifted negatively to 0.21 V. The current density of PdZnO/C electrode is 145 mA cm−2, while that of the Pd/C electrode is 60 mA cm−2. Moreover, single cell discharge test shows that discharge voltage of the PdZnO/C electrode reaches to 0.41 V at 30 mA cm−2. In summary, ZnO as a co-catalyst significantly improves the activity of PdZnO/C catalyst for ethanol oxidation reaction.  相似文献   

10.
The effect of LiCe(BH4)3Cl on the hydrogen storage properties of Mg(NH2)22LiH system was studied systematically, which has a high Li ion conductivity. The hydrogen desorption temperatures for LiMgNH system shift to lower temperatures by 0.05LiCe(BH4)3Cl doping with the onset temperature of dehydrogenation decreasing by 40 °C and the peak temperature decreasing by 30 °C. The Mg(NH2)22LiH–0.03LiCe(BH4)3Cl composite exhibits an improved comprehensive hydrogen storage properties, which can reversibly store about 5.0 wt% hydrogen at 160 °C, and released hydrogen as much as 8.6 times faster than that of the Mg(NH2)22LiH composite at 160 °C. The results indicated that the LiCe(BH4)3Cl-containing sample exhibited much better cycling properties than that of Mg(NH2)22LiH sample. XRD and FTIR results show that the structure of LiCe(BH4)3Cl does not change before and after hydrogen absorption/desorption, indicating it plays the catalytic effect. The hydrogen desorption activation energy of Mg(NH2)22LiH doped with 0.03LiCe(BH4)3Cl was reduced by 37.5%. The rate-controlling step of desorption shifted from the diffusion to the chemical reaction by the addition of LiCe(BH4)3Cl, indicating that the diffusion rates of small ions like H+, Li+ and Mg2+ in LiMgNH system are significantly enhanced, which could be well explained by the improved ionic conductivity of LiCe(BH4)3Cl doped sample.  相似文献   

11.
At present, it is difficult for electrocatalytic electrode materials with high-Performance to be prepared at low cost and large area under mild conditions. Therefore, we adopt a facile electroless plating method to deposit the FeCoP alloys on the nickel foam (NF) with different areas of 1 cm2, 4 cm2, 8 cm2 and 16 cm2. The FeCoP/NF catalysts exhibit extraordinary catalytic activity for the oxygen evolution reaction (OER) in alkaline media and are comparable to the state-of-the-art IrO2 in 1.0 M KOH, capable of yielding a current density of 10 mA cm−2 at an overpotential of only 250 mV. Furthermore, the FeCoP/NF catalysts show efficient activity towards the hydrogen evolution reaction (HER) with an overpotential of 163 mV at j = 10 mA cm−2 as well. Remarkably, when used as both the anode and cathode, a low potential of 1.68 V (vs. RHE) is required to reach the current density of j = 10 mA cm−2, making the FeCoP/NF alloys as an active bifunctional electrocatalyst for overall water splitting. The FeCoP/NF alloy catalysts with high catalytic activity, facile preparation and low cost would provide a new pathway for the design and large-scale application of high-performance bifunctional catalysts for electrochemical water splitting.  相似文献   

12.
In this study, MgH2 and Co powders were mechanically milled in the molar ratio 2:1 and compressed to hard-packed cylindrical pellets. The microstructure, phase changes, and hydrogen storage properties of the mechanically milled 2MgH2Co powder and the 2MgH2Co compressed pellet were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and synchronous thermal (DSC/TG) analyses. Dehydrogenation of the 2MgH2Co compressed pellet is mainly due to the decomposition of Mg2CoH5 while it is the dehydriding of MgH2 for the milled 2MgH2Co powder. Pressure composition absorption isotherms of the 2MgH2Co powder and 2MgH2Co compressed pellet show two and three plateaus, respectively, corresponding to the formation of Mg6Co2H11 and Mg2CoH5 hydride phases. For the compressed 2MgH2Co pellet, enthalpies of formation/decomposition were measured to be −58.11±7.69 kJ/mol H2/55.70±3.34 kJ/mol H2 for Mg2CoH5 and -81.89±10.39 kJ/mol H2/74.47±5.27 kJ/mol H2 for Mg6Co2H11. In contrast, hydrogenation/dehydrogenation enthalpies of Mg2CoH5 and Mg6Co2H11 mechanically milled 2MgH2Co powder were −73.98±10.1 kJ/mol H2/71.67±1.38 kJ/mol H2 and -96.86±8.73 kJ/mol H2/89.95±10.81 kJ/mol H2, respectively. Fast hydrogenation was observed in the dehydrided 2MgH2Co compressed pellet with about 2.75 wt% absorbed in less than 1 min at 300 °C and a maximum hydrogen storage capacity of 4.43 wt% (2.32 wt% for the 2MgH2Co powder) was achieved. The hydrogen absorption activation energy of the 2MgH2Co compressed pellet (64.34 kJ-mol−1 H2) is lower than the mechanically milled 2MgH2Co powder (73.74 kJ-mol−1 H2). The results show that mechanical milling followed by high-pressure compression is an efficient method for the synthesis of Mg-based complex hydrides with superior hydrogen sorption properties.  相似文献   

13.
The effect of Fe content in electroless-deposited CoNi-Fex-P alloy catalysts (x = 5.5–11.8 at.%) from the hydrolysis of NaBH4 is investigated in alkaline sodium borohydride solution. The electroless-deposited CoNiFe5.5-P and CoNiFe7.6-P alloy catalysts are composed of flake-like micron particles; however, with an increase in Fe content to 11.8 at.%, the flake-like morphology is changed to a spherical shape and the crystal structure of the electroless-deposited CoNiFeP catalyst is transformed from FCC to BCC. Among all the CoNi-Fex-P alloy catalysts, the CoNi-Fex-P (x = 7.6 at.%) catalyst has the highest hydrogen production rate of 1128 ml min−1 g−1catalyst in alkaline solution containing 1 wt% NaOH + 10 wt% NaBH4 at 303 K. For the optimized catalyst, the activation energy of the hydrolysis of NaBH4 is calculated to be 54.26 kJ mol−1. Additionally, in this work, we report a new hydrolysis using Mg(BH4)2 and Ca(BH4)2. As a result, the Mg(BH4)2 is stored unstably in an alkaline solution, whereas the Ca(BH4)2 is stored stably. When optimizing the hydrogen production kinetics from the hydrolysis of Ca(BH4)2, the rate is 784 ml min−1 g−1catalyst in 10 wt% NaOH + 3 wt% Ca(BH4)2 solution.  相似文献   

14.
The flame synthesis provides a simple low-cost method to produce novel carbon materials. In this study, N, B co-doped carbon (NBC) materials have been prepared by flame synthesis. Among many as-prepared samples, the NBC catalyst which prepared under carbonization temperature of 1000 °C for 3 h with acetonitrile/acetone precursor of 1:1 exhibits the best catalytic activity and stability, as well as good resistance to methanol interference for oxygen reduction reaction (ORR), with half-wave potential being almost nearly to Pt/C, and a quasi-four-electron transfer process. This study would provide an economic, environmental feasible and scalable approach for fabricating novel heteroatom co-doped carbon materials for ORR applications.  相似文献   

15.
In this paper, we report the performance of supported PdRu membranes for possible applications to hydrogen purification and/or production. For this purpose, we fabricated three ultra-thin α-alumina-supported membranes by combined plating techniques: a PdAg membrane (3 μm-thick ca.) and two PdRu (1.8 μm-thick ca.). The former is set as a benchmark for comparison. The membranes were characterised using different methodologies: permeation tests, thermal treatment and SEM analysis. Preliminary leakage tests performed with nitrogen has revealed that the two PdRu membranes, namely PdRu#1 and PdRu#2, show a non-ideal (non-infinite) selectivity, which is relatively low for the former (around 830 at 400 °C) and sufficiently high for the latter (2645 at 400 °C). This indicates a relevant presence of defects in the PdRu#2 membrane, differently from what observed for the PdAg and PdRu#1 ones. The permeation tests show that the hydrogen permeating flux is stable up to around 550 °C, with an apparently unusual behaviour at higher temperatures (600 °C), where we observe a slightly decrease of hydrogen flux with an increase of the nitrogen one. Moreover, a peculiar bubble-shaped structure is observed in the metal layer of all membranes after usage by means of SEM image analysis. This is explained by considering the effect of the Pd-alloy grain surface energy, which tends to minimise the exposed surface area of the grain interface by creating sphere-like bubble in the lattice, similar to what occurs for soap bubbles in water. The above-mentioned decrease in hydrogen flux at 600 °C is explained to be caused by the bubble formation, which pushes the alloy deeper in the support pores.  相似文献   

16.
Here, a simple two-step solvothermal approach has been employed to synthesize PtFe alloy (or Pt)/CeO2/C with PtFe (or Pt) selective loading on CeO2 nanoparticles. In addition, the selective loading of PtFe alloy or Pt nanoparticles on the surface of CeO2 is achieved under weak alkaline environment, which is mainly attributed to the opposite electrostatic force between H+ enriched on the surface of CeO2 particles and OH covered with carbon supporters. As-prepared PtFe alloy (or Pt)/CeO2/C catalysts with two-stage loading structures show more excellent electro-catalytic efficiency for methanol oxidation as well as duration compared with commercial Pt/C and PtCeO2/C with random loading structure. Further, single-cell assembly based on Pt3Fe/CeO2/C as the anode catalyst exhibits a maximum power density of 31.1 mW cm−2, which is 1.95 times that of an analogous cell based on the commercial Pt/C. These improved performances with considerable low Pt content (<0.3 mg cm−2) are mainly ascribed to the abundant three phase interfaces (PtCeO2 carbon) induced by the selective and efficient dispersion of Pt nanoparticles on ceria.  相似文献   

17.
In this work, a spherical spider web-like structure RuNi/Ni foam catalyst was prepared for hydrogen evaluation from sodium borohydride (NaBH4) by a combination of electroless plating and electroplating. Microstructure, surface morphology, surface area and elemental composition of the RuNi/Ni foam catalyst were analyzed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM-EDS and X-ray Photoelectron Spectroscopy (XPS), Brunauere-Emmette-Teller method (BET, AS-1C-VP), respectively. The influences of RuNi with different molar ratios, NaOH concentration, NaBH4 concentration, and solution temperature on the hydrogen production rate were investigated in this paper. The results showed that the RuNi metals were arrayed densely and uniformly on the surface of Ni foam. The average hydrogen production rate is 360 mL min −1 g−1 in 20 wt % of NaBH4, 1 wt% of NaOH at 30 °C in the presence of the RuNi/Ni foam catalysts. The calculated activation energy was 39.96 kJ mol−1 for hydrogen production from sodium borohydride using the RuNi/Ni foam catalyst.  相似文献   

18.
It is very challenging but still promising to develop highly efficient heterogeneous catalysts for selective hydrogenation of CO2 to methane. Supported bimetallic NiPd/SBA-15 alloy catalysts with a varied ratio of Ni/Pd were prepared by one-pot wet chemical and impregnation method. A series of techniques were employed to characterize the elemental composition and alloy structure of as-synthesized NiPd/SBA-15 catalysts. The alloyed bimetallic NiPd/SBA-15 catalysts showed relatively higher catalytic activity compared with monometallic Pd or Ni-supported SBA-15 and several other published catalysts. The bimetallic catalyst with Ni:Pd atom ratio of 3:1 was most active in the formation of CH4 and yielded 0.93 mol CH4 per mol CO2 at 430 °C. This superior performance can be attributed to enhanced synergy between Ni and Pd with high dispersion of active sites.  相似文献   

19.
To improve the hydrogen storage properties of YZrFe alloys, the alloying with Ti was carried out to obtain Y0.7Zr(0.3-x)TixFe2 (x = 0.03, 0.09, 0.1, 0.2) alloys by different processes. It was expected that Ti would substitute Zr and decrease the lattice constant of YFe2-based C15 Laves phase. All YZrTiFe quaternary alloys consist of the main Y(Zr)Fe2 phase and the minor YFe3 phase. Despite the large solubility of Ti in Zr or Zr in Y, the Ti incorporation into YZrFe alloys results in the inhomogeneity of Y and the segregation of Ti, and thus decreases the hydrogen storage capacity. Only the alloy Y0.7Zr0.27Ti0.03Fe2 containing very few Ti shows the substitution of Ti to Zr and the resultant improvement in the dehydriding equilibrium pressure.  相似文献   

20.
Ni/Al2O3, NiCo/Al2O3MgO and NiCo/Al2O3MgO/NbZr nanocatalysts were prepared by the sol-gel technique with citric acid and tested in the dry reforming of methane (DRM). In this paper, the effects of Nb and Zr addition as promoters in Al2O3MgO supported catalysts on the physicochemical characteristics and the reaction performance in the DRM were investigated. The NbZr promoters are expected to enhance the activity and performance of the catalyst due to its high thermal stability and also improvement in the metal dispersion of the catalyst. The catalysts samples were characterized by FESEM, BET, XRD, TEM, H2-TPR and CO2-TPD techniques. FESEM results demonstrated that NiCo/Al2O3MgO/NbZr has more uniform and well-dispersion of metal than NiCo/Al2O3MgO. The BET results unravel that the addition of NbZr promoters increase the surface area of the synthesized catalyst due to the high surface area of the promoters. There is a formation of MgAl2O4 spinel-type solid solution proved by the XRD and CO2-TPD analysis due to the interaction between alumina lattice and magnesium metal which has high resistance to carbon formation. The DRM reaction is performed in the tubular furnace reactor at 1073.15 K, 1 atm and a CH4/CO2 ratio of unity. The sol-gelled NiCo/Al2O3MgO/NbZr was found to be the most proper choice for DRM which illustrates much higher conversion (86.96% for CH4 conversion and 87.84% for CO2 conversion) compared to the other catalysts. This is due to the strong interaction between active metals and supports, resistance to coke formation and higher stability in DRM reaction.  相似文献   

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