Metal grafted high enthalpy porous solids in hydrogen storage

氢是汽车应用的主要替代燃料，因为它具有最高的单位重量能量，并且只产生副产品水。然而，它的实施一直受到阻碍，因为它很难存储在足够小的空间中。出于这个原因，已经开发出了以紧凑的体积容纳大量氢的固体。在设计这种储氢材料时，最重要的特征是氢与衬底之间的结合强度。这个特征决定了容纳氢或释放氢所需的能量。理想情况下，这个值应该落在既不需要加热也不需要冷却的范围内，因为这对汽车设计提出了过高的要求。我们第一次合成了具有高度集中的位置的材料，这些材料具有接近理想的室温应用结合强度。这是在我们的通过Sigma-H2络合物使用表面结合的金属有机碎片作为主要结合部位。最大结合热22.15kJ/mol是以前观察到的两倍多，表面的钛单元在这个温度下结合2.7H2，在室温下结合1.1H2。这项建议旨在系统地优化和改进这些材料，以及相关的碳基类似物，以达到商业应用的可行性。这些材料还将在魁北克水电、温莎、NREL和NIST通过各种物理技术进行探索，以更全面地了解氢的结合机理，并进一步提高性能。

Hydrogen is the leading alternative fuel for automotive applications because it has the highest energy per unit weight and produces only water as a byproduct.  However, its implementation has been hindered because it is very difficult to store in a small enough space to be practical.  For this reason, solids have been developed which hold large amounts of hydrogen in compact volumes.  The most important feature in designing such a hydrogen storage material is the binding strength between the hydrogen and the substrate.  This feature determines how much energy is required to either hold the hydrogen or release the hydrogen.  Ideally this value would fall in the range where neither heating nor cooling is required because this places excess demands on automobile design.  For the first time materials possessing a high concentration of sites possessing a close to ideal binding strength for room temperature applications have been synthesized.   This was acheived in our labs by using surface-bound organometallic fragments as principle binding sites via a sigma-H2 complex.  The maximum binding enthalpies of 22.15 kJ/mol are more than twice that previously observed, leading to storage values of 22.15% at -196 °C.  The Ti units on the surface bind 2.7 H2 at this temperature and 1.1 H2 at room temperature.  This proposal aims at systematically optimizing and improving these materials, and related carbon-based analogues to the point where commercial applications are feasible.  These materials will also be explored by various physical techniques at Hydro Quebec, Windsor, NREL and NIST in order to more fully understand the binding mechanism of the hydrogen and further improve performance.