Niobium carbide MXene-optics fiber-sensor for high sensitivity humidity detection

Niobium carbide (Nb2CTX) MXene is an emerging two-dimensional material and exhibits promising potential in relative humidity (RH) measurement because of its superior photoelectronic and structural properties. Here, Nb2CTX nanosheets were integrated with microfibers via an optical deposition method, and a fiber-optic-based RH sensing strategy was experimentally demonstrated. The ambient H2O molecules could be absorbed and intercalated into the Nb2CTX sheets, thereby modulating the transmission spectra of the microfiber interferometer. The RH sensing experiments showed that the transmission spectra initially blue-shifted as the RH levels increased from 18.5% to 72.4% RH, and the sensitivity was −86 pm/% RH because the effective refractive index of Nb2CTX changes, whereas the transmission spectra exhibited a red shift in the RH range of 72.4%–95.4% RH with a high sensitivity of 585 pm/% RH because of the structure of Nb2CTX variations. The combination of Nb2CTX MXene and fiber optics exhibits great prospects in the RH sensing field and brings innovative ideas for gas-sensing applications.