Collaboratory for Advanced Computing and Simulations, Department of Computer Science, Department of Physics & Astronomy, University of Southern California, Los Angeles, California 90089-0242, USA.
Phys Rev Lett. 2010 Mar 26;104(12):126102. doi: 10.1103/PhysRevLett.104.126102.
Hydrogen production by metal particles in water could provide a renewable energy cycle, if its reaction kinetics is accelerated. Here, ab initio molecular dynamics simulation reveals rapid hydrogen production from water by a cluster (or superatom) consisting of a magic number of aluminum atoms, Al{n} (for instance, n=12 or 17). We find a low activation-barrier mechanism, in which a pair of Lewis-acid and base sites on the Al{n} surface preferentially catalyzes hydrogen production. This reaction is immensely assisted by rapid proton transport in water via a chain of hydrogen-bond switching events similar to the Grotthuss mechanism, which converts hydroxide ions to water molecules at the Lewis-acid sites and supplies hydrogen atoms at the Lewis-base sites.
如果金属颗粒在水中的产氢反应动力学能够得到加速，那么其产生氢气将为可再生能源循环提供可能。本文通过从头算分子动力学模拟发现，由特定数量的铝原子（例如 n=12 或 17）组成的原子簇（或超原子）可以实现水的快速制氢。我们发现了一种低活化能势垒机制，其中 Al{n}表面的一对路易斯酸和碱位点优先催化产氢。通过类似于质子扩散的协同质子转移机制，即通过氢键转换事件将氢氧根离子转化为路易斯酸位点的水分子，并为路易斯碱位点提供氢原子，从而极大地促进了水中的质子快速传输。
