Hybrid Edge Results in Narrowed Band Gap: Bottom-up Liquid-Phase Synthesis of Bent N = 6/8 Armchair Graphene Nanoribbons

Scalable fabrication of graphene nanoribbons with narrow band gaps has been a nontrivial challenge. Here, we have developed a simple approach to access narrow band gaps using hybrid edge structures. Bottom-up liquid-phase synthesis of bent N = 6/8 armchair graphene nanoribbons (AGNRs) has been achieved in high efficiency through copolymerization between an o-terphenyl monomer and a naphthalene-based monomer, followed by Scholl oxidation. An unexpected 1,2-aryl migration has been discovered, which is responsible for introducing kinked structures into the GNR backbones. The N = 6/8 AGNRs have been fully characterized to support the proposed structure and show a narrow band gap and a relatively high electrical conductivity. In addition, their application in efficient gas sensing has also been demonstrated.

Nanographenes and Graphene Nanoribbons as Multitalents of Present and Future Materials Science

As cut-outs from a graphene sheet, nanographenes (NGs) and graphene nanoribbons (GNRs) are ideal cases with which to connect the world of molecules with that of bulk carbon materials. While various top-down approaches have been developed to produce such nanostructures in high yields, in the present perspective, precision structural control is emphasized for the length, width, and edge structures of NGs and GNRs achieved by modern solution and on-surface syntheses. Their structural possibilities have been further extended from "flatland" to the three-dimensional world, where chirality and handedness are the jewels in the crown. In addition to properties exhibited at the molecular level, self-assembly and thin-film structures cannot be neglected, which emphasizes the importance of processing techniques. With the rich toolkit of chemistry in hand, NGs and GNRs can be endowed with versatile properties and functions ranging from stimulated emission to spintronics and from bioimaging to energy storage, thus demonstrating their multitalents in present and future materials science.

Soluble Graphene Nanoribbons from Planarization of Oligophenylenes

A solution-based chemical synthesis of two graphene nanoribbons with armchair edges is reported. The precursor oligophenylene molecules are synthesized and subjected to oxidative cyclodehydrogenation to afford the target molecules, G-1 and G-2. These molecules have good solubility in organic solvents, and show a large redshift in their absorption edge (up to 185 nm) and emission maximum (up to 125 nm) after planarization. Fibrous structures are formed upon self-assembly of molecules through columnar π-π stacking. Such molecular assemblies may be useful for various applications.

Facile synthesis of shape-controlled graphene–polyaniline composites for high performance supercapacitor electrode materials

The shape-controlled graphene–PANI nanocomposites showing excellent performance as supercapacitor electrode materials were successfully prepared by a facile hydrothermal method without any surfactants.

Bottom-up synthesis of chemically precise graphene nanoribbons

In this article, we describe our chemical approach, developed over the course of a decade, towards the bottom-up synthesis of structurally well-defined graphene nanoribbons (GNRs). GNR synthesis can be achieved through two different methods, one being a solution-phase process based on conventional organic chemistry and the other invoking surface-assisted fabrication, employing modern physics methodologies. In both methods, rationally designed monomers are polymerized to form non-planar polyphenylene precursors, which are "graphitized" and "planarized" by solution-mediated or surface-assisted cyclodehydrogenation. Through these methods, a variety of GNRs have been synthesized with different widths, lengths, edge structures, and degrees of heteroatom doping, featuring varying (opto)electronic properties. The ability to chemically tailor GNRs with tuned properties in a well-defined manner will contribute to the elucidation of the fundamental physics of GNRs, as well as pave the way for the development of GNR-based nanoelectronics and optoelectronics.