Massachusetts Institute of Technology, 77 Massachusetts Avenue 13-5056, Cambridge, Massachusetts 02139, USA.
ACS Nano. 2010 Oct 26;4(10):5647-56. doi: 10.1021/nn101224j.
Density functional theory and the cluster expansion method are used to model 2-10 nm sodium alanate (NaAlH(4)) nanoparticles and related decomposition products Na(3)AlH(6), NaH, and Al. While bulk sodium alanate releases hydrogen in a two-step process, our calculations predict that below a certain size sodium alanate nanoparticles decompose in a single step directly to NaH, Al, and H(2) due to the effect of particle size on decomposition thermodynamics. This may explain why sodium alanate nanoparticles, unlike bulk sodium alanate, have been observed to release hydrogen in the operating temperature range of proton exchange membrane fuel cells. In addition, we identify low-energy surfaces that may be important for the dynamics of hydrogen storage and release from sodium alanate nanoparticles.
密度泛函理论和团簇展开方法被用于模拟 2-10nm 的纳米级丙酸钠（NaAlH(4)）颗粒以及相关的分解产物 Na(3)AlH(6)、NaH 和 Al。虽然大块丙酸钠的释氢过程是分两步进行的，但我们的计算预测，由于颗粒尺寸对分解热力学的影响，低于一定尺寸的丙酸钠纳米颗粒会直接分一步解为 NaH、Al 和 H(2)。这也许可以解释为什么丙酸钠纳米颗粒不同于大块丙酸钠，已被观察到在质子交换膜燃料电池的工作温度范围内释放氢气。此外，我们还确定了一些低能量表面，这些表面可能对丙酸钠纳米颗粒中储氢和放氢的动力学过程非常重要。
