Enhanced Blocking Effect: A New Strategy to Improve the NO Sensing Performance of TiCT by γ-Poly(l-glutamic acid) Modification.

Titanium carbide (TiCT) with a distinctive structure, abundant surface chemical groups, and good electrical conductivity has shown great potential in fabricating superior gas sensors, but several challenges, such as low response kinetics, poor reversibility, and serious baseline drift, still remain. In this work, γ-poly(l-glutamic acid) (γ-PGA) with a blocking effect is exploited to modify TiCT, thereby stimulating the positive response behavior of TiCT and improving its gas sensing performance. On account of the unique synergetic interaction between TiCT and γ-PGA, the response of the flexible TiCT/γ-PGA gas sensor to 50 ppm NOhas been improved to a large extent (average 1127.3%), which is 85 times that of TiCT (only 13.2%). Moreover, the as-fabricated TiCT/γ-PGA sensor not only exhibits a shorter response/recovery time (average 43.4/3 s) compared with the TiCT-based sensor (∼18.5/18.3 min) but also shows good reversibility and repeatability (relative standard deviation (RSD) <1%) at room temperature within 50% relative humidity (RH). The improved gas sensing properties of the TiCT/γ-PGA sensor can be attributed to the enhancement of effective adsorption and the blocking effect assisted by water molecules. Furthermore, the gas sensing response of the TiCT/γ-PGA sensor is studied at different RHs, and humidity compensation of the sensor is carried out using the multiple regression method. This work demonstrates a novel strategy to enhance the gas sensing properties of TiCT by γ-PGA modification and provides a new way to realize highly responsive gas detection at room temperature.