Graphdiyne oxide and graphene oxide sense monovalent cations differently: The alkyne and alkene physicochemistry

Abstract The differences between graphdiyne oxide (GDYO) and graphene oxide (GO) in physicochemistry and functionalities are important for precisely selecting the most suitable carbon allotrope for specific proposes, and essential for our understanding of alkyne and alkene fundamentals. However, the precise distinctions between GDYO and GO in ion sieving and sensing are basically unknown. Here we show that GDYO senses monovalent cations differently from GO. The unique sp-hybridization in GDYO provides it with more affinity with H2O molecules and stronger Coulomb electrostatic repulsion to maintain zeta potential high enough to preserve its interfacial colloidal stability without changes in attachment kinetics in the presence of Na+ and K+. Na+ and K+ freely move through the rotatable triangular cavities of GDYO. By comparison, GO shows less H2O affinity and zeta potential. Colloidal GO aggregates with Na+ and K+. Both GO and GDYO sense concentration changes of bivalent and trivalent ions, resulting in interfacial instability that reaches zeta potential plateaus within narrow lower ion concentrations due to electrostatic force and van der Waals force. The present study discovers characteristics of GDYO sp-hybridization and its role in sensing monovalent cations, and elucidates physicochemical differences between GDYO and GO in sensing ions.