Multi-sensing platform based on 2D monoelement germanane

Abstract

Covalently functionalized germanane is a novel type of fluorescent probe that can be employed in material science and analytical sensing. Here, a fluorometric sensing platform based on methyl-functionalized germanane (CH3Ge) is developed for gas (humidity and ammonia) sensing, pH (1–9) sensing, and anti-counterfeiting. Luminescence (red–orange) is seen when a gas molecule intercalates into the interlayer space of CH3Ge and the luminescence disappears upon deintercalation. This allows for direct detection of gas absorption via fluorometric measurements of the CH3Ge. Structural and optical properties of CH3Ge with intercalated gas molecules are investigated by density functional theory (DFT). To demonstrate real-time and on-the-spot testing, absorbed gas molecules are first precisely quantified by CH3Ge using a smartphone camera with an installed color intensity processing application (APP). Further, CH3Ge-paper-based sensor is integrated into real food packets (e.g., fish and milk) to monitor the shelf life of perishable foods. Finally, CH3Ge-based rewritable paper is applied in water jet printing to illustrate the potential for secret communication with quick coloration and good reversibility by water evaporation.