An electronic nose based on 2D group VI transition metal dichalcogenides/organic compounds sensor array

Rapid volatile organic compounds (VOCs) detection is a hot topic today; in this framework nanomaterials and their tailorable chemistry offer a plethora of compelling opportunities. In this work, Group VI transition metal dichalcogenides (TMDs, i.e., MoS2, WSe2, MoSe2, and WSe2) were functionalized with organic compounds (ellagic acid, tannic acid, catechin, and sodium cholate) able to assist their sonochemical exfoliation in water. The 16 resulting water-dispersed 2D hybrid inorganic/organic TMDs resulted in a few-layer nanoflakes conformation and were used to modify quartz crystal microbalances (QCMs) to equip an e-nose for VOCs determination. The ability of the sensors for the detection of VOCs was assessed on alcohols, terpenes, esters, and aldehydes; the responses were significatively different, confirming the synergic effect of TMD and the organic compound in the interaction with VOCs. The 16 sensors exhibited quantitative responses for VOCs (R2≥0.978) with fast signals recovery (<100 s) and repeatable (RSD ≤9.3%, n = 5), reproducible (RSD ≤12.8%, n = 3) and stable (RSD ≤14.6%, 3 months) signals. As proof of applicability, in an e-nose format, banana aroma evolution during post-harvest ripening was successfully monitored using the 2D TMDs-based sensors array. These data demonstrate that TMDs exfoliated in water with different organic compounds are sustainable functional nanomaterials, able to offer new opportunities in nano-bioelectronic applications.