Tailoring the Electronic\nStructure and Properties\nof Graphdiyne by Cyano Groups

Two-dimensional (2D) materials, such as 2D carbon-based\nsystems,\nhave been recently the subject of intense studies, thanks to their\noptoelectronic properties and promising electronic performances. 2D\ncarbon-based materials such as graphdiyne (GDY) represent an optimal\nplatform for tuning the optoelectronic properties via precise chemical\nfunctionalization. Here, we report a synthetic strategy to precisely\nintroduce cyano groups into the 2D GDY backbone in order to tune the\nelectronic properties of GDY. Three kinds of cyano-modified GDY have\nbeen synthesized, namely, bearing one cyano group (CNGDY), two CN\nin meta (<i>m</i>-CNGDY), and two in para (<i>p</i>-CNGDY) positions. A variety of experimental data as well as first-principles\ncalculations allowed us to elucidate the role of the cyano groups\nin tuning the structural and functional properties of GDYs. We found\nthat an increase in the number of cyano groups reduces the interlayer\nspacing between GDY layers, increases the lithium adsorption amount,\nas well as impacts the lithium diffusion rate, while changes in meta-\nor para-position impact the energy band gap.