Chemical-free sustainable carbon nano-onion as a dual-mode sensor platform for noxious volatile organic compounds

Air quality, water safety, and other environmental requirements can be achieved by monitoring volatile organic compounds (VOCs). Majority of the VOC-sensing materials are expensive or require several chemicals for preparation. Herein, a new carbon-based dual electrochemical and fluorescence-sensitive sensing platform was developed to sense diisopropylamine (DIPA) and dioxane. The carbon nano-onion (CNO) was prepared via a solvent-free hydrothermal process using an autoclave. The designed sensor exhibited fluorescence quenching for ethylenediamine (EDA) and DIPA and fluorescence enhancement for dioxane. The fluorescence experiments showed selectivity toward EDA and high DIPA sensitivity with a detection limit of 16.5 nM. The hydrogen bonding interactions between the surface of the CNO and DIPA helped to achieve high sensitivity. Electrochemical investigations were performed for supporting and complementing the fluorescence results. The synthesized CNOs were deposited on a glassy carbon electrode for electrochemical sensing. The amperometry results showed a sensitive DIPA response with a linear range of 0–40 μM, and a limit of detection of 200 nM. Based on the sensing mechanism, the interaction of the surface functional group of the CNO and the polar nitrogen atom in DIPA molecules resulted in high sensitivity. This renewable carbon material can be effective to monitor toxicity in the future.