Kinetic Isotope Effect in the Hydrogenation and Deuteration of Graphene
Kinetic Isotope Effect in the Hydrogenation and Deuteration of Graphene
复制标题
DOI：
10.1002/adfm.201202355
复制
发表时间：
2013-04-05
影响因子：
19
通讯作者：
Grueneis, Alexander
中科院分区：
文献类型：
--
作者：
Paris, Alessio;Verbitskiy, Nikolay;Grueneis, Alexander
利用含时光电子能谱研究了石墨烯氢化/氘代反应动力学。导致不寻常的动力学同位素效应，石墨烯氘化反应比氢化进行得更快，并导致氘的显著更高的最大覆盖率（D/C约为35%，H/C约为25%）。这些结果可以通过以下事实来解释：在原子状态下，H和D为了与石墨烯反应而具有较低的能量势垒，而在分子形式下，两个原子之间的键必须在石墨烯层上捕获之前被破坏。更重要的是，由于与CD或CH伸缩振动相关的量子力学零点能效应，D比H具有更高的脱附势垒。基于量子力学电子势的分子动力学模拟可以再现实验趋势，并揭示H或D原子在石墨烯上的组分化学吸附，反射和关联解吸过程的贡献。关于电子结构的变化，可调的电子能隙可以通过氘化和氢化诱导。
Time-dependent photoemission spectroscopy is employed to study the kinetics of the hydro-genation/deuteration reaction of graphene. Resulting in an unusual kinetic isotope effect, the graphene deuteration reaction proceeds faster than hydrogenation and leads to substantially higher maximum coverages of deuterium (D/C approximate to 35% vs H/C approximate to 25%). These results can be explained by the fact that in the atomic state H and D have a lower energy barrier to overcome in order to react with graphene, while in the molecular form the bond between two atoms must be broken before the capture on the graphene layer. More importantly, D has a higher desorption barrier than H due to quantum mechanical zero-point energy effects related to the CD or CH stretch vibration. Molecular dynamics simulations based on a quantum mechanical electronic potential can reproduce the experimental trends and reveal the contribution of the constituent chemisorption, reflection, and associative desorption processes of H or D atoms onto graphene. Regarding the electronic structure changes, a tunable electron energy gap can be induced by both deuteration and hydrogenation.