论文标题
有缺陷的单层石墨烯上的氢动力学
Hydrogen dynamics on defective monolayer graphene
论文作者
论文摘要
在存在碳空位的情况下，研究了石墨烯片上的氢动力学。我们使用安装在密度功能的密度函数计算的紧密结合的汉密尔顿，通过分子动力学（MD）模拟分析原子H的运动。氢钝化了靠近空缺的C原子的悬挂键，形成了h位于层平面的一侧或另一侧的H键。已经从MD轨迹的统计分析以及原子坐标的自相关函数中研究了氢动力学。对于单个H原子，我们发现越过石墨烯层的有效屏障为0.40〜EV，跳跃速率$ν= 2 \ times 10^6 $ 〜S $^{ - 1} $在300〜K处。原子的跳跃表现为随机事件，在给定温度和时间间隔的数字遵循泊松概率分布。对于接近空缺的两个H原子，在室温下发现了原子动力学中的强相关性，较低的跳跃频率$ν= 7 \ times 10^2 $ 〜S $^{ - 1} $。这些结果提供了对石墨烯上氢的扩散机制的见解，为通过有缺陷的结晶膜完全理解其运动铺平了道路。
The hydrogen dynamics on a graphene sheet is studied in the presence of carbon vacancies. We analyze the motion of atomic H by means of molecular dynamics (MD) simulations, using a tight-binding Hamiltonian fitted to density-functional calculations. Hydrogen passivates the dangling bonds of C atoms close to a vacancy, forming C--H bonds with H located at one or the other side of the layer plane. The hydrogen dynamics has been studied from statistical analysis of MD trajectories, along with the autocorrelation function of the atomic coordinates. For a single H atom, we find an effective barrier of 0.40~eV for crossing the graphene layer, with a jump rate $ν= 2 \times 10^6$~s$^{-1}$ at 300~K. The atomic jumps behave as stochastic events, and their number for a given temperature and time interval follows a Poisson probability distribution. For two H atoms close to a vacancy, strong correlations in the atomic dynamics are found, with a lower jump frequency $ν= 7 \times 10^2$~s$^{-1}$ at room temperature. These results provide insight into the diffusion mechanisms of hydrogen on graphene, paving the way for a complete understanding of its motion through defective crystalline membranes.
