The present study reports on the introduction of various nanocatalysts containing nickel (Ni) nanoparticles (NPs) embedded within TiO2 nanofibers and TiO2 microparticles. Typically, a sol-gel consisting of titanium isopropoxide and Ni NPs was prepared to produce TiO2 nanofibers by the electrospinning process. Similarly, TiO2 microparticles containing Ni were prepared using a sol-gel syntheses process. The resultant structures were studied by SEM analyses, which confirmed well-obtained nanofibers and microparticles. Further, the XRD results demonstrated the crystalline feature of both TiO2 and Ni in the obtained composites. Internal morphology of prepared nanofibers and microparticles containing Ni NPs was characterized by TEM, which demonstrated characteristic structures with good dispersion of Ni NPs. In addition, the prepared structures were studied as a model for hydrogen production applications. The catalytic activity of the prepared materials was studied by in situ hydrolysis of NaBH4, which indicated that the nanofibers containing Ni NPs can lead to produce higher amounts of hydrogen when compared to other microparticles, also reported in this paper. Overall, these results confirm the potential use of these materials in hydrogen production systems. 1. Introduction In recent years, due to concerns about global warming and the depletion of fossil fuels from the natural reservoirs, the utilization of various other sources of energy had been intensively investigated by scientific society. There are various means of obtaining energy from the natural and artificial resources. Among the various forms of energy, hydrogen has become one of the most promising future energy means of harvesting. However, the production of this important source by direct water splitting without any byproducts is one of potential alternatives to hydrogen fuel for future energy supply [1, 2]. In order to overcome this rising demand for hydrogen, many methods have been devised, such as reforming of natural gas [3, 4], coal gasification [5], biomass pyrolysis and gasification [6], hydrolysis of chemical hydrides [7, 8], and electrolytic or photocatalytic water splitting [1, 2]. Although the hydrogen production by water splitting using electrolysis of alkaline solution is commercially done, the efficiency of the process is low. However, efficiencies are increased through the use of polymer electrolyte membranes and photovoltaic reactions. Recently, there has been a growing interest in hydrogen generation and storage using metal hydrides, such as lithium hydride (LiH) [9], sodium
References
[1]
H. de Battista, R. J. Mantz, and F. Garelli, “Power conditioning for a wind-hydrogen energy system,” Journal of Power Sources, vol. 155, no. 2, pp. 478–486, 2006.
[2]
H. Miland, R. Gl？ckner, P. Taylor, R. Jarle Aaberg, and G. Hagen, “Load control of a wind-hydrogen stand-alone power system,” International Journal of Hydrogen Energy, vol. 31, no. 9, pp. 1215–1235, 2006.
[3]
R. J. Farrauto, “Introduction to solid polymer membrane fuel cells and reforming natural gas for production of hydrogen,” Applied Catalysis B, vol. 56, no. 1-2, pp. 3–7, 2005.
[4]
A. Heinzel, B. Vogel, and P. Hübner, “Reforming of natural gas—hydrogen generation for small scale stationary fuel cell systems,” Journal of Power Sources, vol. 105, no. 2, pp. 202–207, 2002.
[5]
G. J. Stiegel and M. Ramezan, “Hydrogen from coal gasification: an economical pathway to a sustainable energy future,” International Journal of Coal Geology, vol. 65, no. 3-4, pp. 173–190, 2006.
[6]
E. E. Iojoiu, M. E. Domine, T. Davidian, N. Guilhaume, and C. Mirodatos, “Hydrogen production by sequential cracking of biomass-derived pyrolysis oil over noble metal catalysts supported on ceria-zirconia,” Applied Catalysis A, vol. 323, pp. 147–161, 2007.
[7]
S. C. Amendola, S. L. Sharp-Goldman, M. S. Janjua et al., “Safe, portable, hydrogen gas generator using aqueous borohydride solution and Ru catalyst,” International Journal of Hydrogen Energy, vol. 25, no. 10, pp. 969–975, 2000.
[8]
J. H. Kim, K. T. Kim, Y. M. Kang et al., “Study on degradation of filamentary Ni catalyst on hydrolysis of sodium borohydride,” Journal of Alloys and Compounds, vol. 379, no. 1-2, pp. 222–227, 2004.
[9]
J. J. Vajo, S. L. Skeith, F. Mertens, and S. W. Jorgensen, “Hydrogen-generating solid-state hydride/hydroxide reactions,” Journal of Alloys and Compounds, vol. 390, no. 1-2, pp. 55–61, 2005.
[10]
J. O. Jensen, Q. Li, R. He, C. Pan, and N. J. Bjerrum, “100–200？°C polymer fuel cells for use with NaAlH4,” Journal of Alloys and Compounds, vol. 404–406, pp. 653–656, 2005.
[11]
Y. Kojima, K. I. Suzuki, and Y. Kawai, “Hydrogen generation from lithium borohydride solution over nano-sized platinum dispersed on LiCoO2,” Journal of Power Sources, vol. 155, no. 2, pp. 325–328, 2006.
[12]
H. I. Schlesinger, H. C. Brown, A. E. Finholt, J. R. Gilbreath, H. R. Hoekstra, and E. K. Hyde, “Sodium borohydride, its hydrolysis and its use as a reducing agent and in the generation of hydrogen,” Journal of the American Chemical Society, vol. 75, no. 1, pp. 215–219, 1953.
[13]
D. Hua, Y. Hanxi, A. Xinping, and C. Chuansin, “Hydrogen production from catalytic hydrolysis of sodium borohydride solution using nickel boride catalyst,” International Journal of Hydrogen Energy, vol. 28, no. 10, pp. 1095–1100, 2003.
[14]
M. Zahmakiran and S. ？zkar, “Water dispersible acetate stabilized ruthenium(0) nanoclusters as catalyst for hydrogen generation from the hydrolysis of sodium borohyride,” Journal of Molecular Catalysis A, vol. 258, no. 1-2, pp. 95–103, 2006.
[15]
J. A. Ritter, A. D. Ebner, J. Wang, and R. Zidan, “Implementing a hydrogen economy,” Materials Today, vol. 6, no. 9, pp. 18–23, 2003.
[16]
J. H. Kim, H. Lee, S. C. Han, H. S. Kim, M. S. Song, and J. Y. Lee, “Production of hydrogen from sodium borohydride in alkaline solution: development of catalyst with high performance,” International Journal of Hydrogen Energy, vol. 29, no. 3, pp. 263–267, 2004.
[17]
D. L. Calabretta and B. R. Davis, “Investigation of the anhydrous molten Na–B–O–H system and the concept: electrolytic hydriding of sodium boron oxide species,” Journal of Power Sources, vol. 164, no. 2, pp. 782–791, 2007.
[18]
Y. Kojima, K. I. Suzuki, K. Fukumoto et al., “Development of 10？kW-scale hydrogen generator using chemical hydride,” Journal of Power Sources, vol. 125, no. 1, pp. 22–26, 2004.
[19]
N. Patel, B. Patton, C. Zanchetta et al., “Pd–C powder and thin film catalysts for hydrogen production by hydrolysis of sodium borohydride,” International Journal of Hydrogen Energy, vol. 33, no. 1, pp. 287–292, 2008.
[20]
J. S. Zhang, W. N. Delgass, T. S. Fisher, and J. P. Gore, “Kinetics of Ru-catalyzed sodium borohydride hydrolysis,” Journal of Power Sources, vol. 164, no. 2, pp. 772–781, 2007.
[21]
W. Ye, H. Zhang, D. Xu, L. Ma, and B. Yi, “Hydrogen generation utilizing alkaline sodium borohydride solution and supported cobalt catalyst,” Journal of Power Sources, vol. 164, no. 2, pp. 544–548, 2007.
[22]
S. U. Jeong, R. K. Kim, E. A. Cho et al., “A study on hydrogen generation from NaBH4 solution using the high-performance Co–B catalyst,” Journal of Power Sources, vol. 144, no. 1, pp. 129–134, 2005.
[23]
O. Metin and S. ？zkar, “Hydrogen generation from the hydrolysis of sodium borohydride by using water dispersible, hydrogenphosphate-stabilized nickel(0) nanoclusters as catalyst,” International Journal of Hydrogen Energy, vol. 32, no. 12, pp. 1707–1715, 2007.
[24]
J. C. Ingersoll, N. Mani, J. C. Thenmozhiyal, and A. Muthaiah, “Catalytic hydrolysis of sodium borohydride by a novel nickel-cobalt-boride catalyst,” Journal of Power Sources, vol. 173, no. 1, pp. 450–457, 2007.
[25]
R. Pe？a-Alonso, A. Sicurelli, E. Callone, G. Carturan, and R. Raj, “A picoscale catalyst for hydrogen generation from NaBH4 for fuel cells,” Journal of Power Sources, vol. 165, no. 1, pp. 315–323, 2007.
[26]
M. Ziabari, V. Mottaghitalab, and A. K. Haghi, “A new approach for optimization of electrospun nanofiber formation process,” Korean Journal of Chemical Engineering, vol. 27, no. 1, pp. 340–354, 2010.
[27]
G. T. Kim, Y. C. Ahn, and J. K. Lee, “Characteristics of Nylon 6 nanofilter for removing ultra fine particles,” Korean Journal of Chemical Engineering, vol. 25, no. 2, pp. 368–372, 2008.
[28]
F. A. Sheikh, N. A. M. Barakat, M. A. Kanjwal, S. J. Park, D. K. Park, and H. Y. Kim, “Synthesis of poly(vinyl alcohol) (PVA) nanofibers incorporating hydroxyapatite nanoparticles as future implant materials,” Macromolecular Research, vol. 18, no. 1, pp. 59–66, 2010.
[29]
M. A. Kanjwal, N. A. M. Barakat, F. A. Sheikh, W. I. Baek, M. S. Khil, and H. Y. Kim, “Effects of silver content and morphology on the catalytic activity of silver-grafted titanium oxide nanostructure,” Fibers and Polymers, vol. 11, no. 5, pp. 700–709, 2010.
[30]
Y. Chen and H. Kim, “Use of a nickel-boride-silica nanocomposite catalyst prepared by in-situ reduction for hydrogen production from hydrolysis of sodium borohydride,” Fuel Processing Technology, vol. 89, no. 10, pp. 966–972, 2008.
[31]
F. A. Sheikh, M. A. Kanjwal, H. Y. Kim, and H. Kim, “Fabrication of titanium dioxide nanofibers containing hydroxyapatite nanoparticles,” Applied Surface Science, vol. 257, no. 1, pp. 296–301, 2010.
[32]
F. A. Sheikh, N. A. M. Barakat, M. A. Kanjwal et al., “Electrospun titanium dioxide nanofibers containing hydroxyapatite and silver nanoparticles as future implant materials,” Journal of Materials Science: Materials in Medicine, vol. 21, no. 9, pp. 2551–2559, 2010.
[33]
F. A. Sheikh, N. A. M. Barakat, M. A. Kanjwal, S. H. Jeon, H. S. Kang, and H. Y. Kim, “Self synthesize of silver nanoparticles in/on polyurethane nanofibers: nano-biotechnological approach,” Journal of Applied Polymer Science, vol. 115, no. 6, pp. 3189–3198, 2010.
[34]
M. A. Kanjwal, N. A. M. Barakat, F. A. Sheikh, M. S. Khil, and H. Y. Kim, “Functionalization of electrospun titanium oxide nanofibers with silver nanoparticles: strongly effective photocatalyst,” International Journal of Applied Ceramic Technology, vol. 7, no. 1, pp. E54–E63, 2010.
