Graphdiyne as Electrode Material: Tuning Electronic State and Surface Chemistry for Improved Electrode Reactivity

Graphdiyne (GDY) is recently synthesized two-dimensional carbon allotrope with hexagonal rings cross-linked by diacetylene through introducing butadiyne linkages (−C≡C–C≡C−) to form 18-C hexagons and is emerging to be fundamentally interesting and particularly useful in various research fields. In this study, we for the first time find that GDY can be used as an electrode material with reactivity tunable by electronic states and surface chemistry of GDY. To demonstrate this, GDY is oxidized into graphdiyne oxide (GDYO) that is then chemically and electrochemically reduced into chemically reduced GDYO (cr-GDYO) and electrochemically reduced GDYO (er-GDYO), respectively. Electrode reactivity of GDY and its derivatives (i.e., GDYO, cr-GDYO, and er-GDYO) is studied with hexaammineruthenium chloride ([Ru(NH3)6]Cl3) and potassium ferricyanide (K3Fe(CN)6) as redox probes. We find that electron transfer kinetics of the redox probes employed here at GDYs depends on the density of electronic state (DOS) and the synergetic effects of the surface chemistry as well as the hydrophilicity of the materials, and that the electron transfer kinetics at cr-GDYO and er-GDYO are faster than those at GDY and GDYO, and quite comparable with those at carbon nanotubes and graphene and its derivatives (i.e., GO, cr-GO, and er-GO). These properties, combined with the unique electronic and chemical structures of GDY, essentially enable GDY as a new kind of electrode material for fundamental studies on carbon electrochemistry and various electroanalytical applications.