摘要
Nanoscale CeAl4 was directly synthesized by the thermal reaction between CeH2 and nano-aluminum at300℃.Then nano CeAl4-doped sodium alanate（NaAlH4）was synthesized by ball milling NaH/Al with 0.04CeAl4under hydrogen atmosphere at room temperature,and the catalytic efficiency of nanoscale CeAl4 for hydrogen storage of NaAlH4 was systematically investigated.It is shown that CeAl4 can effectively improve the dehydrogenation properties of sodium alanate system.The 0.04CeAl4-doped NaAlH4 system starts to release hydrogen below 80℃,completes dehydrogenation within 10 min at 170℃,and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature（100-140℃）.Apparent activation energy of the dehydrogenation of NaAlH4 can be effectively reduced by addition of CeAl4,resulting in the decrease in desorption temperatures.Moreover,by analyzing the reaction kinetics of nano CeAl4-doped NaAlH4sample,both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism.The mechanistic investigations gained here can help to understand the de-/rehydrogenation behaviors of catalyzed complex metal hydride systems.
Nanoscale CeAl4 was directly synthesized by the thermal reaction between CeH2 and nano-aluminum at300℃.Then nano CeAl4-doped sodium alanate（NaAlH4）was synthesized by ball milling NaH/Al with 0.04CeAl4under hydrogen atmosphere at room temperature,and the catalytic efficiency of nanoscale CeAl4 for hydrogen storage of NaAlH4 was systematically investigated.It is shown that CeAl4 can effectively improve the dehydrogenation properties of sodium alanate system.The 0.04CeAl4-doped NaAlH4 system starts to release hydrogen below 80℃,completes dehydrogenation within 10 min at 170℃,and exhibits good cycling de/hydrogenation kinetics at relatively lower temperature（100-140℃）.Apparent activation energy of the dehydrogenation of NaAlH4 can be effectively reduced by addition of CeAl4,resulting in the decrease in desorption temperatures.Moreover,by analyzing the reaction kinetics of nano CeAl4-doped NaAlH4sample,both of the decomposition steps are conformed to a two-dimensional phase-boundary growth mechanism.The mechanistic investigations gained here can help to understand the de-/rehydrogenation behaviors of catalyzed complex metal hydride systems.
基金
financially supported by the National High Technology Research&Development Program of China(No.2012AA051503)
the National Natural Science Foundation of China(Nos.51171173 and 51471151)
the China Postdoctoral Science Foundation(No.2012M521167)
the Program for Innovative Research Team in University of Ministry of Education of China(No.IRT13037)
the Zhejiang Provincial Science&Technology Program of China(Nos.2014C31134 and 2015C31035)
