二维材料中的氢隧穿研究进展

摘要

One-atom-thick material such as graphene, graphene derivatives and graphene-like materials, usually has a dense network lattice structure and therefore dense distribution of electronic clouds in the atomic plane. This unique structure makes it have great significance in both basic research and practical applications. Studies have shown that molecules, atoms and ions are very difficult to permeate through these above-mentioned two-dimensional materials. Theoretical investigations demonstrate that even hydrogen, the smallest in atoms, is expected to take billions of years to penetrate through the dense electronic cloud of graphene. Therefore, it is generally considered that one-atom-thin materialis impermeable for hydrogen. However, recent experimental results have shown that the hydrogen atoms can tunnel through graphene and monolayer hexagonal boron nitride at room temperature. The existence of defects in one-atom-thin material can also effectively reduce the barrier height of the hydrogen tunneling through graphene. Controversy exists about whether hydrogen particles such as atoms, ions or hydrogen molecules can tunnel through two-dimensional materials, and it has been one of the popular topics in the fields of two-dimensional materials. In this paper, the recent research progressof hydrogen tunneling through two-dimensional materials is reviewed. The characteristics of hydrogen isotopes tunneling through different two-dimensional materials are introduced. Barrier heights of hydrogen tunneling through different graphene and graphene-like materials are discussed and the difficulties in its transition are compared. Hydrogen cannot tunnel through the monolayer molybdenum disulfide, only a little small number of hydrogen atoms can tunnel hrough graphene and hexagonal boron nitride, while hydrogen is relatively easy to tunnel through silicene and phosphorene. The introduction of atomic defects or some oxygen-containing functional groups into the two-dimensional material is discussed, which can effectively reduce the barrier height of the hydrogen tunneling barrier. By adding the catalyst and adjusting the temperature and humidity of the tunneling environment, the hydrogen tunneling ability can be enhanced and the hydrogen particles tunneling through the two-dimensional material can be realized. Finally, the applications of hydrogen tunneling through two-dimensional materials in ion-separation membranes, fuel cells and hydrogen storage materials are summarized. The potential applications of hydrogen permeable functional thin film materials, lithium ion battery electrode materials and nano-channel ions in low energy transmission are prospected. The exact mechanism of hydrogen tunneling through two-dimensional material is yet to be unravelled. In order to promote these applications and to realize large-scale production and precision machining of these two-dimensional materials, an in-depth understanding of the fundamental questions of the hydrogen tunneling mechanism is needed. Further studies are needed to predict the tunneling process quantitatively and to understand the effects of catalyst and the influences of chemical environments.%石墨烯、石墨烯衍生物以及类石墨烯材料通常具有致密的网状晶格结构,研究表明这类材料对分子、原子和离子具有很强的阻挡性.然而对于不同形态的氢粒子(原子、离子、氢气分子)是否能够隧穿二维材料仍然存在很多科学争议,并已成为目前科学研究的一个热点.本文综述了氢隧穿二维材料的研究进展,介绍了不同结构氢粒子隧穿二维材料体系的特点,阐述了氢粒子隧穿不同质量石墨烯和类石墨烯材料时所需要逾越的势垒高度,并对比了其跃迁的难度.讨论了从二维材料本身出发,降低氢隧穿势垒大小和改变环境对氢隧穿过程的影响,实现氢粒子隧穿二维材料.最后展望了氢隧穿二维材料在实际应用中可能存在的问题及未来的研究方向.