Acetone Sensing on Graphdiyne: Electrochemical Impedance Spectroscopy Performance and Mechanism Determination.

Hydrogen-substituted graphdiyne (HsGDY) is a conjugated carbon material containing sp- and sp2-hybridized carbon atoms that has recently been shown to mechanically actuate upon exposure to acetone, suggesting a strong molecular interaction. Here, we report the first acetone sensor based on HsGDY films synthesized directly on copper foil. Electrochemical impedance spectroscopy reveals pronounced, concentration-dependent impedance changes upon acetone exposure that are absent in bare copper and carbon paper electrodes and strongly suppressed after thermal treatment that reduces alkyne retention. Distribution-of-relaxation-times analysis indicates that acetone primarily alters mass-transport processes within the HsGDY network. Raman spectroscopy shows no detectable change in the alkyne vibrational signature, whereas solid-state 13C NMR reveals clear structural evolution, highlighting the importance of complementary characterization. Structurally related solvents do not produce comparable responses, demonstrating selectivity toward acetone. These results establish HsGDY as a room-temperature acetone sensor and clarify the mass-transfer-dominated mechanism underlying its response.