We present an investigation of the structural and electronic properties of an ordered grain boundary (GB) formed by separated pentagon–heptagon pairs in single-layer graphene/SiO2 using scanning tunneling microscopy/spectroscopy (STM/STS), coupled with density functional theory (DFT) calculations. It is observed that the pentagon–heptagon pairs, i.e., (1,0) dislocations, form a periodic quasi-one-dimensional chain. The (1,0) dislocations are separated by 8 transverse rows of carbon rings, with a period of ∼2.1 nm. The protruded feature of each dislocation shown in the STM images reflects its out-of-plane buckling structure, which is supported by the DFT simulations. The STS spectra recorded along the small-angle GB show obvious differential-conductance peaks, the positions of which qualitatively accord with the van Hove singularities from the DFT calculations.

A new carbon-based two-dimensional crystalline nanostructure was discovered. The nanostructure was facilely constructed by chemical vapor deposition of benzene on Cu(111) in an ultrahigh vacuum chamber. A low temperature scanning tunneling microscopy and spectroscopy study of the nanostructure indicated that it has an orthorhombic superstructure and a semiconductor character with an energy gap of 0.8 eV. An X-ray photoelectron spectroscopy study showed that C–C(sp2) bonding is predominantly preserved, suggesting a framework consisting of π-conjugated building blocks. The periodic nanostructure was found to be a surprisingly excellent template for isolating and stabilizing magnetic atoms: Co atoms deposited on it can be well dispersed and form locally ordered atomic chains with their atomic magnetism preserved. Therefore the nanostructure may be suitable for organic spintronic applications. The most likely structural model for the nanostructure is proposed with the aid of density functional theory calculations and simulations, suggesting that the 2D nanostructure may consist of polyphenylene chains interconnected by Cu adatoms.

The local structural and electronic properties of the epitaxial monolayer graphene (MG) on Ru(0001) surface were investigated by using scanning tunneling microscopy/spectroscopy (STM/STS) and first-principles calculations. High resolution STM images and STS spectra measured in a large bias voltage range indicated both geometric and electronic corrugation of the MG. The local work function (LWF) of the MG/Ru(0001) surface was obtained to be around 3.5 eV by two separate methods based on the experimental dz/dV and I–z curves respectively. We also found a considerable LWF difference (about 100 to 200 meV) between different sites within a unit cell of the moiré pattern of MG/Ru(0001). Furthermore, noticeable bias-polarity-dependence of the local barrier height (LBH) of MG on Ru(0001) surface was observed, supporting the existence of the Smoluchowski smoothing effect due to the presence of surface dipole moment in consequence of strong MG–Ru interactions. These findings indicate that MG/Ru(0001) can be used as an ideal template for periodic nanostructures with various applications.