Enhanced Blocking Effect: A New Strategy to Improve the NO₂ Sensing Performance of Ti₃C₂T_x by γ-Poly(l-glutamic acid) Modification

Abstract

Titanium carbide (Ti3C2T x ) 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 Ti3C2T x , thereby stimulating the positive response behavior of Ti3C2T x and improving its gas sensing performance. On account of the unique synergetic interaction between Ti3C2T x and γ-PGA, the response of the flexible Ti3C2T x /γ-PGA gas sensor to 50 ppm NO2has been improved to a large extent (average 1127.3%), which is 85 times that of Ti3C2T x (only 13.2%). Moreover, the as-fabricated Ti3C2T x /γ-PGA sensor not only exhibits a shorter response/recovery time (average 43.4/3 s) compared with the Ti3C2T x -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 Ti3C2T x /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 Ti3C2T x /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 Ti3C2T x by γ-PGA modification and provides a new way to realize highly responsive gas detection at room temperature.

Edge‐Enriched Mo2TiC2Tx/MoS2 Heterostructure with Coupling Interface for Selective NO2 Monitoring

“…Technology Co., Ltd. Mo 2 TiC 2 T x was synthesized by typical HF etching and TMAOH intercalation according to the works. [ 38 ] Different from other MXenes (such as Ti 3 C 2 T x or Nb 2 CT x ), the Al atom layer of Mo 2 TiAlC 2 is difficult to remove, thus two HF etchings and one intercalation were performed. First, 3 g Mo 2 TiAlC 2 powder was slowly added to 45 mL 40% HF aqueous solution, and mixed solution was stirred at 300 rpm and 55 °C for 96 h. The above slurry was centrifuged with deionized water for six times.…”

“…As shown in Figure S20 (Supporting Information), the gas sensing performances of the gas sensors were measured by a dynamic homemade system with the Keithley 2700 at room temperature with 50% RH, referring to the pervious works. [ 38 ] Different gas concentrations (2.5 ppb−50 ppm) were obtained by adjusting the mass flow ratios of dry air, humid air, and target gases. Response of sensor was defined as the following equation: Response = | R a ‐ R g |/ R g × 100% ( R g : resistance under target gas with 50% RH, R a : resistance under air with 50% RH).…”

Amine-functionalized stable Nb2CTx MXene toward room temperature ultrasensitive NO2 gas sensor

“…The response of modified Ti 3 C 2 T x MXene shows a sensing response that is 85% stronger than that of pristine Ti 3 C 2 T x MXene at 50 ppm NO 2 gas. 21 Alkalized V 2 CT x MXene with accordion-like structure was synthesized by mild etching, followed by alkaline treatment. The alkalized V 2 CT x MXene showed 80 times stronger response than pristine V 2 CT x MXene at 50 ppm NO 2 gas.…”

Fabrication of high-performance cell-imprinted polymers based on AuNPs/MXene composites via metal-free visible light-induced ATRP

“…15 In addition, Ti 3 C 2 T x has a negatively charged surface and excellent hydrophilic properties due to abundant functional groups on its surface, which makes it suitable as a substrate to self-assemble with positively charged ions or substances to form heterogeneous structures. 16 On the basis of the mentioned characteristics, Ti 3 C 2 T x has been a focus material regarding environment adsorption, energy storage, catalysis, and sensors. 17 AuNPs are the most stable metal nanomaterials.…”