펑딩 교수

The periodic makeup of carbon nanotubes suggests that their formation should obey the principles established for crystals. Nevertheless, this important connection remained elusive for decades and no theoretical regularities in the rates and product type distribution have been found. Here we contend that any nanotube can be viewed as having a screw dislocation along the axis. Consequently, its growth rate is shown to be proportional to the Burgers vector of such dislocation and therefore to the c

Density functional theory is used to show that the adhesion between single-walled carbon nanotubes (SWNTs) and the catalyst particles from which they grow needs to be strong to support nanotube growth. It is found that Fe, Co, and Ni, commonly used to catalyze SWNT growth, have larger adhesion strengths to SWNTs than Cu, Pd, and Au and are therefore likely to be more efficient for supporting growth. The calculations also show that to maintain an open end of the SWNT it is necessary that the SWNT

Synthesizing bilayer graphene (BLG), which has a band gap, is an important step in graphene application in microelectronics. Experimentally, it was broadly observed that hydrogen plays a crucial role in graphene chemical vapor deposition (CVD) growth on a copper surface. Here, by using ab initio calculations, we have revealed a crucial role of hydrogen in graphene CVD growth, terminating the graphene edges. Our study demonstrates the following. (i) At a low hydrogen pressure, the graphene edges

Two dimensional (2D) materials consist of one to a few atomic layers, where the intra-layer atoms are chemically bonded and the atomic layers are weakly bonded. The high bonding anisotropicity in 2D materials make their growth on a substrate substantially different from the conventional thin film growth. Here, we proposed a general theoretical framework for the epitaxial growth of a 2D material on an arbitrary substrate. Our extensive density functional theory (DFT) calculations show that the pr

Molecular dynamics simulations based on an empirical potential energy surface were used to study iron catalyzed nucleation and growth of single-walled carbon nanotubes (SWNTs). The simulations show that SWNTs grow from iron-carbide particles at temperatures between 800 and 1400 K, whereas graphene sheets encapsulate the particle at temperatures below 600 K and a three-dimensional soot-like structure is formed above 1600 K. Nucleation of these carbon (C) structures can be divided into three stage

Graphene, the thinnest two-dimensional material in nature, has abundant distinctive properties, such as ultrahigh carrier mobility, superior thermal conductivity, very high surface-to-volume ratio, anomalous quantum Hall effect, and so on. Laterally confined, thin, and long strips of graphene, namely, graphene nanoribbons (GNRs), can open the bandgap in the semimetal and give it the potential to replace silicon in future electronics. Great efforts are devoted to achieving high-quality GNRs with

The successful exfoliation of graphene has given a tremendous boost to research on various two-dimensional (2D) materials in the last 15 years. Different from traditional thin films, a 2D material is composed of one to a few atomic layers. While atoms within a layer are chemically bonded, interactions between layers are generally weak van der Waals (vdW) interactions. Due to their particular dimensionality, 2D materials exhibit special electronic, magnetic, mechanical, and thermal properties, no

The energetics and growth kinetics of graphene edges during CVD growth on Cu(111) and other catalyst surfaces are explored by density functional theory (DFT) calculations. Different from graphene edges in vacuum, the reconstructions of both armchair (AC) and zigzag (ZZ) edges are energetically less stable because of the passivation of the edges by the catalytic surface. Furthermore, we predicated that, on the most used Cu(111) catalytic surface, each AC-like site on the edge is intended to be pa

Abstract Metal corrosion is a long‐lasting problem in history and ultrahigh anticorrosion is one ultimate pursuit in the metal‐related industry. Graphene, in principle, can be a revolutionary material for anticorrosion due to its excellent impermeability to any molecule or ion (except for protons). However, in real applications, it is found that the metallic graphene forms an electrochemical circuit with the protected metals to accelerate the corrosion once the corrosive fluids leaks into the in