Whole-Process Mildly Prepared TiO₂@Ag Composite Material for Printed, Flexible, and Room-Temperature NH₃ Sensing

Abstract

A processing strategy to prepare flexible gas sensors that can detect ammonia (NH3) gas at room temperature was proposed in this study. All of the procedures, including material preparation and sensor fabrication, were carried out at mild temperature of no more than 70 °C. Different proportions of silver nanoparticles (AgNPs) were doped on TiO2 nanoparticles to form TiO2@Ag composite materials from reactive silver precursors via a facile heating and stirring process. NH3 gas sensors with different sensitive patterns were produced by the additive printing process based on the ultrasonic resonance principle. Flexible poly­(ethylene terephthalate) (PET) with interdigital electrodes (IDEs) was used as the substrate. Facile post-treatment of hot-pressing at a mild temperature of 70 °C was applied to improve the adhesion strength of the sensitive layer to the flexible substrate. Characterizations were carried out to confirm the morphological, elemental, crystal information, and elemental states of the TiO2@Ag composite material. Gas-sensing tests were implemented at different conditions to study the gas-sensing property and mechanism of the flexible sensor. The modified ASTM tape test was applied to inspect the adhesion strength of the sensitive layer on the PET substrate. The whole-process mild strategy of coupling printing technology with hot-press treatment can be extended to the preparation of various kinds of flexible gas sensors.

1D/2D Heterostructured WS2@PANI Composite for Highly Sensitive, Flexible, and Room Temperature Ammonia Gas Sensor

“…Several categories of ammonia-sensitive materials, including metal oxide, − carbon-based materials (graphene, carbon nanotubes, and their derivates), conductive polymers, − and transition metal disulfides (TMDs) − have been used for the ammonia gas sensor. Among those materials mentioned above, conductive polymers and TMDs are more promising from the perspective of a room temperature (RT) response property.…”

UV activated single aligned TiO2 nanofiber embedded silver nanoparticles as room temperature ammonia gas sensor

“…When TiO 2 (n-type semiconductor) absorbs oxygen from the surrounding environment, ionic oxygen species ( -O , 2 O − ) will be produced. When it is exposed to both oxidizing and reducing gases the resistance will increase for oxidizing gases while decreases for reducing gases such as NH 3 [25,26]. Upon UV light exposure on TiO 2 , electron-hole pairs are generated and facilitates the absorption of oxygen on TiO 2 surface.…”

“…In previous works, some TiO 2 and Ag@TiO 2 -based structures have been investigated as NH 3 sensors [25][26][27]. Among the ammonia sensors, those which are working at room temperature (RT) are highly desirable due to their lower power consumption [28,29].…”