Search

2D materials raised extensive attention for physical-, chemical- and wearable-sensors, among others. The principal reason is the outstanding capability of 2D materials to detect specific analytes and physical stimuli through diverse responses. After a short introduction to 2D materials, a critical explanation of sensors containing 2D materials is provided to justify their applications. Following by a description of the most relevant transduction mechanisms of 2D materials employed for sensing. This review explores their advancement and implementation in sensing during the last decade in several areas, such as physical, chemical, bio and wearable sensors. Different types of 2D materials, including graphene, transition metal dichalcogenides (TMDs), hexagonal boron nitride (h-BN), 2D carbides and nitrides of transition metals (MXenes) and black phosphorus (BP), are considered.

In this paper the first example of using C-dots (CDs) as sensing nanomaterial for monitoring low concentrations of NO2 in ambient air is reported. In the logic to support a green circular economy, CDs were prepared from a natural low cost precursor consisting in olive solid waste (OSW) by a simple pyrolysis process combined with chemical oxidation. Characterization data showed the formation of spherical CDs with dimensions in the narrow size range from 0.5 to 5 nm and charged with functional groups (COO- (carboxylate), C-O-C (epoxide) and C-OH (hydroxyl) imprinting excellent water colloidal dispersion. The nanomaterial was used to fabricate and test a conductometric gas sensor (CDs-sensor) that was found to exhibit excellent performances in terms of high and selective response to sub-ppm concentration of NO2 at low temperature (150 °C), low limit of detection (LOD) of 50 ppb, good reproducibility and stability over use and aging. To the best of our knowledge, this is the first example reported in the literature of CDs high performances gas sensing material. Results here presented pave the way for a new class of a carbon nanomaterial for gas sensing to be applied in the field of environmental monitoring.