Effect of different modification agents on hydrogen-generation by the reaction of Al with water Zhen-Yan Deng a, *, Ye-Bin Tang a , Li-Li Zhu a , Yoshio Sakka b , Jinhua Ye b a Energy Materials & Physics Group, Department of Physics, Shanghai University, Shanghai 200444, China b National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan article info Article history: Received 27 January 2010 Received in revised form 11 April 2010 Accepted 2 July 2010 Available online 4 August 2010 Keywords: Hydrogen-generation Aluminum Modification agent Surface modification abstract Three different modification agents, g-Al 2 O 3 , a-Al 2 O 3 , and TiO 2 were used to modify Al particle surfaces. The effect of different modification agents on hydrogen-generation by the reaction of modified Al powder with water was investigated. It was found that different modification agents have different effect on the reaction dynamics of Al with water. The complete hydrogen-generation time of g-Al 2 O 3 modified Al powder is obviously shorter than that of a-Al 2 O 3 and TiO 2 modified Al powders, because of their different induction time for the beginning of the reaction. Possible mechanism analyses indicated that the phase transformation and resultant weakening of Al particle surface layer during pro- cessing strongly depends on the nucleation energy barrier on modification oxide grains. As g-Al 2 O 3 has a low nucleation energy barrier, the phase transformation of Al particle surface layer is relatively complete so that g-Al 2 O 3 modified Al powder has a short induction and complete reaction time with water. This implies that the Al surface modification probably originates from the phase change of its surface layer. ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. 1. Introduction Fossil fuel depletion and air pollution arising from its combustion have spurred scientists to develop new clean and renewable energy technologies [1e3]. Hydrogen is an ideal fuel, because its oxidation product (water) is environmentally benign. However, storage and transportation of hydrogen remain a problem, due to its low boiling point (252  C) and very poor compressibility. To solve this problem, scientists have done much endeavor. One way is to develop hydrogen- storage materials; in the pressure and temperature ranges attractive for mobile storage (1e10 bar, 1e100  C), the reversibly stored amount of hydrogen for the current storage materials is 1e2 wt%, far below the target of 6.5 wt% of the U.S. Department of Energy [1,4,5]. Another way is to develop hydrogen- generation materials, which could be used for small portable fuel cells and the kW-grade fuel cells being as the energy sources for fieldwork or military use [3]. Currently, there are two main hydrogen-generation materials, one is methanol and another is sodium borohydride (NaBH 4 ) [6,7]. However, both of them have some shortcomings. For example, reforming of methanol not only generates hydrogen but also CO. CO has a serious poisoning effect on anode of the fuel cells [8], and removal of the CO traces is a challenge for a fuel cell system. For NaBH 4 , it requires a definite amount of NaOH as a stabilizing agent, and the hydrogen-generation reaction of NaBH 4 with water needs the aid of the special catalysts. Use of NaOH and catalysts undoubtedly increases the technology complexity and cost. Moreover, the current high price of NaBH 4 (w55 $ kg 1 ) attenuates its competitiveness for commercial * Corresponding author. Tel.: þ86 21 66134334; fax: þ86 21 66134208. E-mail address: zydeng@shu.edu.cn (Z.-Y. Deng). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 35 (2010) 9561 e9568 0360-3199/$ e see front matter ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.07.027