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1.
The key to direct methanol fuel cells (DMFCs) is the anode catalyst for methanol oxidation reaction (MOR) which has good catalytic activity and stability. Pt@CoOx@N-C catalysts were synthesized by compounding Pt nanoparticles and CoOx with nitrogen-doped porous carbon (N-C). Pt nanoparticles were prepared by solution plasma technique. CoOx@N-C are derived from zeolitic-imidazolate-framework-67 (ZIF-67) by heat treatment at 700 °C. For MOR, Pt@CoOx@N-C exhibits an outstanding electrocatalytic performance (mass activity of 2400 mA mgPt−1) and stability (70% remained after 300 cycles) under acidic condition, which owing to the synergistic effects among the Pt nanoparticles, CoOx and nitrogen-doped porous carbon. Pt@CoOx@N-C shows such mass activity superior to that of Pt/C (460 mA mgPt−1) due to the fact that CoO can adsorb –OH in the solution and then assist Pt to oxidize the CO-like intermediates to CO2 which improves the resistance to CO poisoning of Pt nanoparticles. Therefore, solution plasma method assisted with metal-organic frameworks have good development prospects on synthesis of highly efficient electrocatalysts.  相似文献   

2.
Research on water splitting reaction is on priority to explore an alternative source of energy with little to no carbon emissions. Among the two half reactions of electrochemical water splitting, oxygen evolution reaction (OER) is highly desirable yet challenging to prepare a cost effective and viable electrocatalyst to boost the OER activity. Herein, we have prepared a novel electrocatalyst, CoOx-CoP/N-CNTs, by the phosphidization of cobalt oxides (CoOx) encapsulated N- doped carbon nanotubes (CoOx/N-CNTs). The CoOx/N-CNTs composite is derived via pyrolysis of cobalt based zeolitic imidazole framework (ZIF-12) at 950 °C under argon atmosphere. The CoOx/N-CNTs is phosphidized at various temperatures ranging from 320 °C to 400 °C. The optimized temperature to attain the best catalytic activity is 380 °C. The phosphatized material, CoOx-CoP/N-CNTs, shows superior performance towards OER with an overpotential of 250 mV @ 20 mAcm?2 vs 532 mV @ 20 mAcm?2 of un-phosphidized material, CoOx/N-CNTs, which shows significant effect of phosphidization. The maximum current density of 160 mAcm?2 in 1 M KOH solution is achieved.  相似文献   

3.
Ammonia borane hydrolysis is a promising strategy for developing sustainable hydrogen energy. However, this reaction is not kinetically feasible at ambient temperature, thus developing a proper catalyst is indispensable. In this work, Porous carbon is facilely prepared from cattail fibers by using K2CO3, and then used to stabilize Ru nanoparticles. The effects of different synthesis parameters for the biomass-derived carbon supports (e. g. K2CO3 dosage and calcination temperature) and various catalytic reaction conditions (e. g. the amounts of the catalysts, ammonia borane and NaOH, and reaction temperature) on the hydrolysis rate of ammonia borane are investigated. Benefitting from the interconnected hierarchical pores of the optimal porous carbon (p-C), which was prepared with a mass ratio of 6 : 1 for K2CO3 to cattail fibers and calcined at 873 K, and the high dispersion of Ru nanoparticles, the optimal Ru/p-C catalysts exhibit excellent catalytic performance. The corresponding apparent activation energy (28.8 kJ mol?1) and turnover frequency (744.7 min?1 in alkaline solution) are superior to many catalysts previously reported. This work offers a competitive catalyst for the hydrolytic dehydrogenation of chemical hydrogen storage materials.  相似文献   

4.
Well-dispersed palladium nanoparticles (NPs) anchored on a porous N-doped carbon is prepared by wet chemical method, using metal organic frameworks (ZIF-8) as a precursor to derive the porous N-doped carbon support. Benefitting from the N-doping and the porous structure of the carbon materials, the final Pd NPs are in high dispersion and exhibit reduced particle sizes, with electronic structure and chemical status tuned to favor the formic acid decomposition (FAD). The prepared Pd/CZIF-8-950 catalysts show enhanced catalytic performance and selectivity for FAD, the turnover of frequency (TOF) and the mass activity up to 1166 h−1 and 11.01 mol H2 g−1 pd h−1 were obtained at 30 °C. This work provides an effective and easy way for synthesis the Pd-based catalyst, which has enormous application prospects for the next generation hydrogen energy preparation and storage.  相似文献   

5.
Herein, we report an efficient, environmentally friendly and stable catalyst development to hydrogen evolution from sodium borohydride hydrolysis. For this purpose, Ruthenium complex catalyst successfully fabricated via 5-Amino-2,4-dichlorophenol-3,5-ditertbutylsalisylaldimine ligand and RuCl3·H2O salt. Ru complex catalyst was identified with X-Ray Diffraction Analysis, Infrared Spectroscopy, Elemental Analysis, Transmission electron microscopy, Scanning Electron Microscope and Brunauer-Emmett-Teller Surface Area Analysis. According to the analysis results, it was confirmed that Ru complex catalyst was successfully synthesized. Ru complex was used as a catalyst in NaBH4 hydrolysis. The kinetic performance of Ru complex catalyst was evaluated at various reaction temperatures, various sodium borohydride concentration, catalyst concentration and sodium hydroxide concentration in hydrogen evolution. The apparent activation energy for the hydrolysis of sodium borohydride was determined as 25.8 kJ mol?1. With fully conversion, the promised well durability of Ru complex was achieved by the five consecutive cycles for hydrogen evolution in sodium borohydride hydrolysis The hydrogen evolution rates were 299,220 and 160,832 mL H2 gcat?1 min?1 in order of at 50 °C and 30 °C. Furthermore, the proposed mechanism of Ru complex catalyzed sodium borohydride hydrolysis was defined step by step. This study provides different insight into the rational design and utilization and catalytic effects of ruthenium complex in hydrogen evolution performance.  相似文献   

6.
Developing an efficient catalyst for hydrogen (H2) generation from hydrolysis of ammonia borane (AB) to significantly improve the activity for the hydrogen generation from AB is important for its practical application. Herein, we report a novel hybrid nanostructure composed of uniformly dispersed Co@Co2P core-shell nanoparticles (NPs) embedded in N-doped carbon nanotube polyhedron (Co@Co2P/N–CNP) through a carbonization-phosphidation strategy derived from ZIF-67. Benefiting from the electronic effect of P doping, high dispersibility and strong interfacial interaction between Co@Co2P and N-CNTs, the Co@Co2P/N–CNP catalyst exhibits excellent catalytic performance towards the hydrolysis of AB for hydrogen generation, affording a high TOF value of 18.4 mol H2 mol metal?1 min?1 at the first cycle. This work provides a promising lead for the design of efficient heterogeneous catalysts towards convenient H2 generation from hydrogen-rich substrates in the close future.  相似文献   

7.
Sodium borohydride has been widely regarded as a promising hydrogen carrier owing to its greatly hydrogen storing capability (10.8 wt%), high weight density and excellent stability in alkaline solutions. Herein, we first design and synthesize a series of bimetallic M-Ru/C nanocomposites (including Fe–Ru/C, Co–Ru/C, Ni–Ru/C and Cu–Ru/C), via simply alloying of commercial Ru/C with nonprecious metal, for superior H2 evolution from the NaBH4 hydrolysis. The result exhibits that H2 generation is synergetically improved by alloying Ru/C with Co or Ni, while it is hindered by alloying Ru/C with Fe or Cu. Indeed, Co–Ru/C presents the highest efficient catalytic activity for H2 generation, with the TOF of 117.69 mol(H2)·molRu?1·min?1, whereas Ru/C is only 57.08 mol(H2)·molRu?1·min?1. In addition, the TOF of Co–Ru/C reaches to 436.51 mol(H2)·molRu?1·min?1 (96.7 L(H2)·gRu?1·min?1) in the presence of NaOH.  相似文献   

8.
Efficient and controllable release of hydrogen from solid hydrogen storage materials is a promising way to produce hydrogen safely and on-demand. The development of economical, highly active, easily recyclable catalysts is critical for practical applications, which remains a great challenging. Herein, the easily controllable and cost-effective corrosion strategy is ingeniously developed to simply prepare ultralow-content ruthenium coupled with nickel hydroxide on nickel foam (Ru–Ni–NF). After experiencing the spontaneous oxidation-reduction reactions between the reactive NF and Ru3+, ultrafine Ru nanoparticles decorated nickel hydroxide nanosheets are in situ intimately grown on porous NF networks. The optimal Ru–Ni–NF catalyst exhibits the excellent performance for catalytic hydrolysis of ammonia borane with a high turnover frequency (TOF) of 539.6 molH2 molRu?1 min?1 at 298 K and a low apparent activation energy of 36.4 kJ mol?1, due to the synergistic effect between Ru nanoparticles and nickel hydroxide nanosheets. Furthermore, the Ru–Ni–NF catalyst possesses easy separation and outstanding durability, which is superior to powdered catalysts. This study provides a facile and economical strategy for the preparation of ultralow-content noble metal supported metal foam-type catalysts for dehydrogenation of ammonia borane.  相似文献   

9.
Nickel based materials are the most potential catalysts for COx-free hydrogen production from ammonia decomposition. However, the facile synthesis of supported Ni-based catalysts with small size Ni particles, high porosity and good structural stability is still of great demand. In this work, uniform small-sized Ni particles supported into porous alumina matrix (Ni@Al2O3) are synthesized by a simple one-pot method and used for ammonia decomposition. The Ni content is controlled from 5 at.% to 25 at.%. Especailly, the 25Ni@Al2O3 catalyst shows the best catalytic performance. With a GHSV of 24,000 cm3gcat?1h?1, 93.9% NH3 conversion is achieved at 600 °C and nearly full conversion of NH3 is realized at 650 °C. The hydrogen formation rate of 25NiAl catalyst reaches 3.6 mmol gcat?1min?1 at 400 °C and 7.8 mmol gcat?1min?1 at 450 °C. The enhanced activity observed on 25Ni@Al2O3 catalyst can be attributed to the structural characteristic that large amounts of uniform-sized small (7.2 ± 0.9 nm) Ni particles are highly dispersed into porous alumina matrix. The aggregation of active metallic Ni particles during the high temperature reaction can be effectively prevented by the porous alumina matrix due to the strong interaction between them, thus ensuring a good catalytic performance.  相似文献   

10.
To exploit the low-cost and efficient catalyst for the hydrolytic dehydrogenation of ammonia borane, trace amount of palladium-doped transition metal (Cu, Ni, Co, Fe and Zn) nanoparticles have been incorporated into the interior of metal-organic frameworks named ZIF-8, ZIF-67, ZIF-67/ZIF-8 and core-shell ZIF-67@ZIF-8 by a double-solvent approach. The optimized catalyst of CuPd0.01@ZIF-67@ZIF-8 composite exhibited an excellent activity with a turnover frequency (TOF) value of 30.15 mol H2 (molmetal)−1 min−1 at 298 K and a relatively low activation energy of 38.78 kJ mol−1. It might attributed to both ultrafine size of metal nanoparticles (~3 nm) induced by the confinement of core-shell ZIF-67@ZIF-8 and the synergistic effect between Pd and Cu. Moreover, the detailed kinetic study has manifested that this catalytic reaction is first-order in regards to the catalyst amount while zero-order as for the concentration of ammonia borane. In addition, the durability and recyclability of CuPd0.01@ZIF-67@ZIF-8 have been demonstrated to be great.  相似文献   

11.
In this paper, ruthenium supported on nitrogen-doped porous carbon (Ru/NPC) catalyst is synthesized by a simple method of in situ reduction using ammonia borane (AB) as reducing agent. The composition and structure of Ru/NPC catalyst are systematically characterized. This catalyst can efficiently catalyze the hydrolysis of AB. The hydrogen production reaction is completed within about 90 s at a temperature of 298 K and the maximum rate of hydrogen production is 3276 ml·s−1·g−1 with a reduced activation energy of 24.95 kJ·mol−1. The turnover frequency (TOF) for hydrogen production is about 813 molH2·molRu−1·min−1. Moreover, this catalyst can be recycled with a well-maintained performance. After five cycles, the maximum rate of hydrogen generation is maintained at 2206 ml·s−1·g−1, corresponding to 67.3% of the initial catalytic activity. Our results suggest that Ru/NPC prepared by in situ reduction is a highly efficient catalyst for hydrolytic dehydrogenation of AB.  相似文献   

12.
The development of Ni-based catalysts with outstanding anti-coking ability is necessary for realizing the industrial application of dry reforming of CH4 (DRM) to syngas. Here, a facile combustion method with unique characteristic was employed to prepare the Ni/SiO2 catalyst with different promoters (ZrO2 or Ru). The effects of Ni particle size and promoter (ZrO2 or Ru) on the anti-coking ability of Ni/SiO2 catalyst were examined. The XRD and TEM results showed that improved Ni dispersion can be obtained via the facile combustion method, accompanying with enhanced metal-support interaction and CO2 adsorption capacity confirmed by H2-TPR and CO2-TPD, respectively. In comparison with Ni-IMP catalyst (prepared via the traditional impregnation method), the carbon deposition over Ni–C catalyst (prepared via the combustion method) decreased by 67% (from 2.7 to 0.9 mg carbon deposition·g?1CH4) as a result of the small Ni particles. The H2-TPR and XPS results revealed the interaction between promoter (ZrO2 and Ru) and Ni. The addition of ZrO2 can enhanced the CO2 activation ability of catalyst and the formed oxygen species can facilitate the elimination of carbon species, further decreasing the carbon deposition compared with Ni–C catalyst. The best catalytic performance with least carbon deposition (only 0.4 mg carbon deposition·g?1 CH4) is achieved on the NiRu–C catalyst. The slower CH4 dissociation rate and the improved CO2 activation benefited from Ru can bring in the better balance between the carbon formation and elimination, leading to the best anti-coking ability of catalyst.  相似文献   

13.
At present, a novel and active catalyst, RuW/MWCNT catalyst, was successfully synthesized to complete the hydrolysis reaction of sodium borohydride (NaBH4). The activity of Ru catalyst was increased by adding tungsten (W) to ruthenium (Ru) on multi-walled carbon nanotube (MWCNT) support. Surface characterization of the catalyst was performed with scanning electron microscope (SEM-EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmissing electron microscope (TEM) analysis methods. SEM-EDX revealed that RuW (95:5) catalyst metal ratio was obtained at desired nominal ratio. XRD characterization revealed that W addittion to the Ru structure increased its activity by forming an alloy. W addition Ru altered the electronic structure of the Ru. Parameters affecting the hydrolysis performance of RuW/MWCNT catalyst such as temperature, amount of catalyst, NaBH4 concentration and sodium hydroxide (NaOH) concentration were investigated. Adding NaOH to the reaction vessel reduced the activity of the RuW/MWCNT catalyst. From the hydrolysis measurements, the activation energy of RuW(95–5)/MWCNT catalyst was found to be 16.327 kjmol?1, the reaction order as 0.61 and the initial rate as 95,841,4 mL H2gcatmin?1. The stability of the RuW/MWCNT catalyst was tested using 5 times and it was observed that this novel RuW/MWCNT catalyst could complete the hydrolysis reaction despite repeated use.  相似文献   

14.
Performance of electrocatalysts towards oxygen-involving reactions is strongly associated with the surface and interface properties. Cobalt phthalocyanine (CoPc) materials have been widely explored as oxygen-involving electrocatalysts but their intrinsic catalytic activity is always poor. We present here a surface oxygen plasma approach to directly treat CoPc for producing interfacial CoOx nanodots anchored on CoPc (CoOx/CoPc), which exhibits high activity towards both oxygen reduction reactions (ORR) and oxygen evolution reactions (OER). The optimized CoOx/CoPc demonstrates a much better catalytic activity with a half-wave potential of 0.63 V and an average electron transfer number of 3.64 than the CoPc (0.59 V and n = 2.37) towards ORR in alkaline media. Moreover, OER performance of the CoOx/CoPc is also significantly enhanced, showing a current density of 22.2 mA cm?2 that is 36 times higher than that of CoPc (0.6 mA cm?2) at an overpotential of 0.49 V. It is found that the enhanced performance of the CoOx/CoPc is attributed to the high electrochemical active surface area, highly active CoOx, as well as desired interfacial structure.  相似文献   

15.
Ligand-free Ru nanoclusters supported on carbon black have been synthesized in situ for the first time from the reduction of RuCl3 by ammonia-borane concomitantly with its hydrolysis process at room temperature, and their catalytic activity has been investigated. Well dispersed Ru nanoclusters (∼1.7 nm) are stabilized and immobilized by carbon black. Due to the small size and the absence of ligands on the surface, the Ru catalysts exhibit high catalytic activity, which is partly retained after 5 reaction cycles. A kinetic study shows that the catalytic hydrolysis of ammonia-borane is first order with respect to Ru catalyst concentration; the turnover frequency is 429.5 mol H2 min−1 mol−1 Ru. The activation energy for the hydrolysis of ammonia-borane in the presence of Ru/C catalysts has been measured to be 34.81 ± 0.12 kJ mol−1, which is smaller than most of the values reported for other catalysts, including those based on Ru, for the same reaction.  相似文献   

16.
Cyclic life of catalyst for hydrolysis of sodium borohydride is one of the key issues, which hinder commercialization of hydrogen generation from sodium borohydride (NaBH4) solution. This paper is aimed at promoting the cyclic life of Ru/Ni foam catalysts by employing an electro-deposition method. The effect of hydrolysis parameters on hydrolysis of sodium borohydride was studied for improving the catalytic performance. It is found that the hydrogen generation rate (HGR) of the hydrolysis reaction catalyzed by Ru/Ni foam catalyst can reach as high as 23.03 L min?1 g?1 (Ru). The Ru/Ni foam catalyst shows good catalytic activity after a cycleability test of 100 cycles by rinsing with HCl, which is considered as more effective method than rinsing with water for recovering the performance of Ru/Ni foam catalyst.  相似文献   

17.
Rational fabrication of highly efficient and non-precious metal electrocatalysts for oxygen evolution reaction (OER) are of great importance for renewable energy exploitation to solving the energy crisis and environmental problems. In this paper, we report a novel hybrid nanostructure with Co, Ni and S co-doped N-enriched porous carbon polyhedron (CoNixSy/NCP) via a absorption-pyrolysis-sulfuration strategy derived from zeolitic imidazolate framework-67 (ZIF-67) and explored its electrocatalytic performance for OER. During the synthesis process, Ni2+ is abosrbed within the pores or surface of ZIF-67 and Ni/ZIF-67 can be transformed into the Co and Ni co-doped porous carbon frameworks when it is sulfurazed at 800 °C. NiS2 and NiCo2S4 nanoparticles formed at high temperature are homogeneously dispersed in porous carbon and can activate its electrocatalytic performance. The porous carbon can enhance the electrochemical surface area and charge transfer efficiency. Benefiting from the synergistic effects between highly active NiS2, NiCo2S4, and porous carbon, CoNixSy/NCP electrocatalyst exhibits excellent electrocatalytic performance. The results show that CoNixSy/NCP also exhibits a potential as low as 1.51 V to achieve 10 mA/cm2 current density and extremely stability towards OER. The good electrocatalytic activity of CoNixSy/NCP further suggest its great potential as an efficient eletctocatalyst for sustainable energy applications.  相似文献   

18.
In present paper, the preparation and catalytic activity of Eupergit C polymer (EC) modified Co complex was reported. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller Surface Area Analysis (BET), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) coupled with energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) were used to characterization of catalyst. EC modified-Co complex was the first time examined as a catalyst in NaBH4 hydrolysis to H2 evolution. The kinetic calculations were determined by using two different kinetic methods. The low activation energy barriers were achieved as 21.673 kJ mol?1 for nth order model and as 21.061kJmol?1 for Langmuir-Hinshelwood (L-H) model at low temperatures. EC modified-Co complex catalyst exhibited high performance with H2 evolution rates of 3914 mL H2gcat?1min?1 and 9183 mLH2gcat?1min?1 at 30 °C–50 °C. Additionally, Langmuir–Hinshelwood mechanism was explained for EC modified Co complex catalyzed sodium borohydride hydrolysis reaction. The reusability experiments showed that EC modified-Co complex catalyst maintained excellent stability with 100% conversion and without significant lost after the 6th run.  相似文献   

19.
The hydrolysis of sodium borohydride (NaBH4) over catalysts is a promising method to produce hydrogen. Although Co-based catalysts exhibit high activity for NaBH4 hydrolysis, they are still far from satisfying practical applications, especially their poor durability in alkaline media. Herein, a carbon shell structure was designed and synthesized to improve the stability of the mixture of Co0 and CoxOy nanofilms (Co/CoxOy@C) during NaBH4 hydrolysis via a facile polymerization-pyrolysis strategy with Co/CoxOy nanofilms as the precursor. As a result, the Co/CoxOy@C catalyst can achieve a remarkable H2 generation rate of 4348.6 mL min?1 gCo?1 with a low activation energy of 43.6 kJ mol?1, which is superior to most previously reported catalysts. Moreover, the catalyst shows high stability with an H2 generation-specific rate of 79% after five cycles. The excellent performance of carbon substrate can well prevent the agglomeration of Co-based nanoparticle and improve the corrosion resistance of the active Co to BO2? and OH?. This work would widen the road for the preparation of nanoconfined catalysts, which has prospective application potentials for H2 production from NaBH4 hydrolysis.  相似文献   

20.
In this work, poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium nanoparticles (NPs) supported on bamboo leaf-derived porous carbon (Ru/BC) has been synthesized via a one-step procedure. The structure and morphology of the as-synthesized samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). As a catalyst for hydrogen generation from the hydrolysis of ammonia-borane (AB, NH3BH3) at room temperature, Ru/BC stabilized with 1 mg of PVP exhibited high activity (TOF = 718 molH2·molRu−1·min−1) and low activation energy (Ea = 22.8 kJ mol−1). In addition, the catalyst could be easily recovered and showed fairly good recyclability with 55.6% of the initial catalytic activity retained after ten experimental cycles, which confirmed that PVP could stabilize the Ru NPs and prevent their agglomeration on BC surface. Our results suggest that PVP-stabilized Ru/BC is a highly efficient catalyst for the hydrolysis of AB.  相似文献   

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