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A study on the effects of Fex/Niy/MgO(1-x-y) catalysts on the volumetric and electrochemical hydrogen storage of multi-walled carbon nanotubes
, Article International Journal of Hydrogen Energy ; Volume 35, Issue 1 , 2010 , Pages 231-237 ; 03603199 (ISSN) ; Mortazavi, S. Z ; Zaker Moshfegh, A ; Nozad Golikand, A ; Sharif University of Technology
Abstract
The effects of various ratios of Fe/Ni/MgO and growth temperatures on yield, diameter and quality of multi-walled carbon nanotubes (MWCNTs) were studied. Thermal gravimetric analysis (TGA) confirmed that the MWCNT yield depends on Fe/Ni ratio with the following order; Fe0.5 Ni0.5 > Fe > Fe0.75 Ni0.25 > Fe0.25 Ni0.75 > Ni. The results indicated that there is an optimum temperature (940 °C) for the MWCNT growth both from quality and quantity (yield) aspects as compared to other temperatures. Moreover, the changes on Fe/Ni to MgO ratio for the MWCNT growth revealed that Fe/Ni/MgO with the ratio of 17.5/17.5/65 had the highest quality and surface area as compared to the other ratios. The...
Influence of annealing on the electrochemical behavior of finemet amorphous and nanocrystalline alloy
, Article Journal of Materials Science ; Volume 45, Issue 2 , 2010 , Pages 546-551 ; 00222461 (ISSN) ; Nozad Golikand, A ; Madaah Hosseini, H. R ; Asgari, M ; Sharif University of Technology
Abstract
The electrochemical corrosion behavior of finemet alloy at various heat treatment temperatures was investigated. Thermal behavior and structural changes were studied using differential scanning calorimetry and X-ray diffractometry, respectively. The electrochemical corrosion of amorphous and annealed samples was investigated in 0.10 M NaOH solution using electrochemical impedance spectroscopy and linear sweep voltammetery. Changes in morphology of the samples before and after corrosion were characterized using optical microscope. The results showed that structural relaxation and nanocrystallization during the heat treatment improved corrosion behavior of the alloy. The heat-treated alloy at...
The effects of multi-walled carbon nanotubes graphitization treated with different atmospheres and electrolyte temperatures on electrochemical hydrogen storage
, Article Electrochimica Acta ; Volume 55, Issue 16 , June , 2010 , Pages 4700-4705 ; 00134686 (ISSN) ; Nozad Golikand, A ; Mortazavi, S. Z ; Irannejad, L ; Moshfegh, A. Z ; Sharif University of Technology
2010
Abstract
Using multi-walled carbon nanotubes (MWCNTs), the present study focuses on their electrochemical hydrogen storage capacities. The results showed that the hydrogen desorption process is composed of two steps with voltages around -0.75 and -0.15 V. Hydrogen adsorption at -0.15 V took place at temperatures above 30 °C, and the amount of energy required for adsorbing hydrogen was 1.68 eV. The hydrogen storage capacity increased with increasing electrolyte temperature from 30 to 60 °C in both steps. The hydrogen storage capacity of the MWCNTs treated at different atmospheres showed that the decrease in the graphitization of MWCNTs led to the increase in hydrogen adsorption. The results also...
The effect of various acids treatment on the purification and electrochemical hydrogen storage of multi-walled carbon nanotubes
, Article Journal of Power Sources ; Volume 183, Issue 2 , 1 September , 2008 , Pages 539-543 ; 03787753 (ISSN) ; Mortazavi, S. Z ; Nozad Golikand, A ; Moshfegh, A. Z ; Mirershadi, S ; Sharif University of Technology
Elsevier
2008
Abstract
The effects of HCl, HNO3, H2SO4 and HF acids on the purification and the electrochemical hydrogen storage of multi-walled carbon nanotubes (MWCNTs) were studied. The MWCNTs were synthesized on Fe-Ni catalyst by thermal chemical vapor deposition method. The X-ray diffraction and thermal gravimetric analysis results indicated that the MWCNTs purified by HF acid had the highest impurities as compared with the other acids. The N2 adsorption results at 77 K indicated that all the samples were mainly mesoporous and the purified MWCNTs by HF acid had the highest surface area as compared with the other acids. The hydrogen storage capacities of the purified MWCNTs by the following acids were in...