Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
ACS Nano. 2011 May 24;5(5):4056-64. doi: 10.1021/nn200643b. Epub 2011 Apr 5.
Nanoparticles of NaAlH(4) have been infiltrated in nanoporous carbon aerogel with TiCl(3) nanoparticles in order to explore possible synergetic effects between nanoconfinement and a functionalized catalytic scaffold. Resorcinol formaldehyde carbon aerogels with an average pore size of 17 nm and total pore volume of 1.26 mL/g were infiltrated with TiCl(3) to obtain an aerogel doped with 3.0 wt % TiCl(3) nanoparticles. NaAlH(4) was melt-infiltrated into the functionalized carbon aerogel at 189 °C and p(H(2)) ∼ 186-199 bar. Energy-dispersive spectrometry (EDS) combined with focused ion beam (FIB) techniques revealed the presence of Na, Al, Ti, and Cl inside the aerogel scaffold material. The infiltrated NaAlH(4) was X-ray amorphous, whereas (27)Al magic-angle spinning (MAS) NMR spectroscopy confirmed the presence of nanoconfined NaAlH(4). Temperature-programmed desorption mass spectroscopy (TPD-MS) and Sieverts' measurements demonstrated significantly improved hydrogen desorption kinetics for this new nanoconfined NaAlH(4)-TiCl(3) material as compared to nanoconfined NaAlH(4) without the catalysts TiCl(3) and to bulk ball-milled samples of NaAlH(4)-TiCl(3). We find that the onset temperature for hydrogen release was close to room temperature (T(onset) = 33 °C), and the hydrogen release rate reached a maximum value at 125 °C, which demonstrates favorable synergetic effects between nanoconfinement and catalyst addition.
已将纳米 NaAlH(4) 颗粒渗透到具有纳米 TiCl(3) 颗粒的纳米多孔碳气凝胶中，以探索纳米限域和功能化催化支架之间可能存在的协同效应。用平均孔径为 17nm 和总孔体积为 1.26ml/g 的间苯二酚甲醛碳气凝胶渗透 TiCl(3)，得到掺杂 3.0wt%TiCl(3)纳米颗粒的气凝胶。NaAlH(4)在 189°C 和 p(H(2))∼186-199bar 下渗透到功能化碳气凝胶中。能量色散光谱(EDS)与聚焦离子束(FIB)技术的结合表明，Na、Al、Ti 和 Cl 存在于气凝胶支架材料中。渗透的 NaAlH(4)为非晶态，而(27)Al 魔角旋转(MAS)NMR 光谱证实了纳米限域 NaAlH(4)的存在。程序升温脱附质谱(TPD-MS)和 Sieverts 测量表明，与没有催化剂 TiCl(3)的纳米限域 NaAlH(4)和纳米限域 NaAlH(4)-TiCl(3)的块状球磨样品相比，这种新的纳米限域 NaAlH(4)-TiCl(3)材料的氢气释放动力学得到了显著改善。我们发现，氢气释放的起始温度接近室温(T(onset)=33°C)，氢气释放速率在 125°C 时达到最大值，这表明纳米限域和催化剂添加之间存在有利的协同效应。
