Flexible NH3 gas sensor based on TiO2/cellulose nanocrystals composite film at room temperature

In this work, substrate material cellulose nanocrystals (CNCs) and sensitive material titanium dioxide (TiO2) were fabricated through a one-step-forming process, followed by the analysis of morphology, transmittance, and thermal stability. The mechanical properties of the composite film with different content of TiO2 (0%, 1%, 3%, 6%, and 10%) were then analyzed. Subsequently, the TiO2/CNCs composite films were used in research for a wearable NH3 gas sensor. Comparative gas sensing results revealed that the wearable gas sensor based on a 6% TiO2/CNCs composite film responded at a higher level to NH3 gas at room temperature than other TiO2 contents. The 6% TiO2/CNCs composite film sensor with robust selectivity, stability, and repeat-use functionality reached the response value at 1.34–435 ppm NH3. Additionally, under UV radiation, the 6% TiO2/CNCs composite film-based gas sensor exhibited improved gas sensitivity to NH3.