Enhanced Blocking Effect: A New Strategy to Improve the NO2 Sensing Performance of Ti3C2Tx by γ-Poly(L-glutamic acid) Modification

Titanium carbide (Ti3C2Tx) 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, gamma-poly(L-glutamic acid) (gamma-PGA) with a blocking effect is exploited to modify Ti3C2Tx, thereby stimulating the positive response behavior of Ti3C2Tx and improving its gas sensing performance. On account of the unique synergetic interaction between Ti3C2Tx and gamma-PGA, the response of the flexible Ti3C2Tx/gamma-PGA gas sensor to 50 ppm NO(2)has been improved to a large extent (average 1127.3%), which is 85 times that of Ti3C2Tx (only 13.2%). Moreover, the as-fabricated Ti3C2Tx/gamma-PGA sensor not only exhibits a shorter response/recovery time (average 43.4/3 s) compared with the Ti3C2Tx-based sensor (similar to 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 Ti3C2Tx/gamma-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 Ti3C2Tx/gamma-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 Ti3C2Tx by gamma-PGA modification and provides a new way to realize highly responsive gas detection at room temperature.

Automated summary

The study demonstrates the enhancement of gas sensing properties of Ti3C2Tx by gamma-PGA modification, resulting in improved response to NO2, faster response/recovery time, better reversibility, and repeatability. The improved gas sensing properties of the Ti3C2Tx/gamma-PGA sensor can be attributed to the enhancement of effective adsorption and the blocking effect assisted by water molecules.