Motivated by such a challenge, a research team led by Prof. SONG Fei at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a novel approach to precisely fabricate well-defined GNRs with the tailored pentagon carbon embedded inside, supported on the Ag(111) model catalyst. 

The results were published in Journal of Physical Chemistry Letters entitled "On-Surface Synthesis of Pentagon-Incorporated Graphene-Like Nanoribbons with Multiple Precursors”. 

Compared to the conventional solution-synthesis chemistry, on-surface Ullmann coupling strategy introduces feasibility and controllability on demand towards the atomically precise nanostructures of well-modified GNRS, by programmed cleavage of carbon-halogen bonding in precursors and the reconnection of carbon-carbon bonding on surface. 

Moreover, by utilizing multiple precursors as designed, carbon pentagon structures can be feasibly introduced into GNRs via Ullmann coupling and cyclodehydrogenation on Ag(111), resulting the artificial modification of both nanostructures and electronic structures with the high stability, as witnessed by scanning tunneling spectroscopy (STS) and density function theory (DFT).

This study provides a novel strategy to promote on-surface GNRs-based nanostructures towards field effect transistors (FET), high-density storage devices, etc. 

On-surface synthesis of pentagon-incorporated Graphene Nanoribbons (Image by SARI)