Recent Progress on Flexible Room-Temperature Gas Sensors Based on Metal Oxide Semiconductor

With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.

High-performance flexible sensing devices based on polyaniline/MXene nanocomposites

Highly active two-dimensional(2D)nanocomposites,integrating the unique merits of individual components and synergistic effects of composites,are greatly desired for flexible sensing device applications.Although 2D transition metal carbides and nitrides(MXenes)combined with their high metallic conductivity and versatile surface chemistry have shown its huge potential for sensing reactions,it still remains a major challenge to construct functional materials with intriguing sensing performance at room temperature(RT).Herein,we used an integration of density functional theory(DFT)simulations and bulk electrosensitive measurements to show high electrocatalytic sensitivity of polyaniline/MXene(PANI/Ti3C2Tx)nanocomposites.Thanks to the synergistic properties of nanocomposites and high catalytic/absorption capacity of Ti3C2Tx MXene,PANI nanoparticles are rationally decorated on Ti3C2Tx nanosheet surface via in situ polymerization by low temperature approach to induce remarkable detection sensitivity,rapid response/recovery rate,and mechanical stability at RT.This study offers a versatile platform to use MXenes to fabricate 2D nanocomposites materials for high-performance flexible gas sensors.

Deposition of In2O3 nanofibers on polyimide substrates to construct high-performance and flexible trimethylamine sensor

Flexible trimethylamine sensor has been realized based on In2 O3 nanofibers via electrospinning and a deposition technique.The web-like In2O3 nanofibers with high length-to-diameter ratios are benefit for gas adsorption and desorption.High trimethylamine sensing properties are observed.The sensors can detect trimethylamine gas down to 1 ppm at 80℃with the response up to 3.8.Additionally,rapid response(6 s)and recovery(10 s)behavior can also be obtained.Good reliability and flexibility are observed in 100 bending/extending cycles.Our results open a new route to construct flexible gas sensors in practice.