Surface Functionalization of Ti₃C₂T_x MXene with Highly Reliable Superhydrophobic Protection for Volatile Organic Compounds Sensing

Abstract

Two-dimensional (2D) transition-metal carbides (Ti3C2T x MXene) have received a great deal of attention for potential use in gas sensing showing the highest sensitivity among 2D materials and good gas selectivity. However, one of the long-standing challenges of the MXenes is their poor stability against hydration and oxidation in a humid environment, limiting their long-term storage and applications. Integration of an effective protection layer with MXenes shows promise for overcoming this major drawback. Herein, we demonstrate a surface functionalization strategy for Ti3C2T x with fluoroalkylsilane (FOTS) molecules through surface treatment, providing not only a superhydrophobic surface, mechanical/environmental stability but also enhanced sensing performance. The experimental results show that high sensitivity, good repeatability, long-term stability, and selectivity and faster response/recovery property were achieved by the FOTS-functionalized when Ti3C2T x was integrated into chemoresistive sensors sensitive to oxygen-containing volatile organic compounds (ethanol, acetone). FOTS functionalization provided protection to sensing response when the dynamic response of the Ti3C2T x -F sensor to 30 ppm of ethanol was measured over in the 5 to 80% relative humidity range. Density functional theory simulations suggested that the strong adsorption energy of ethanol on Ti3C2T x -F and the local structure deformation induced by ethanol adsorption, contributing to the gas-sensing enhancement. This study offers a facile and practical solution for developing highly reliable MXene based gas-sensing devices with response that is stable in air and in the presence of water.

Advances in MXene Films: Synthesis, Assembly, and Applications

“…Moreover, given the Ti 3 C 2 T x is fully covered with active surface terminations, selectivity toward various gases may also be adjusted by ligand functionalization or defect control. For example, Ti 3 C 2 T x sensors via surface treatment with fluoroalkylsilane (FOTS) molecules provide a superhydrophobic surface, mechanical/environmental stability, and enhanced sensing performance for oxygen-containing VOCs (acetone, ethanol, and 2-propanol) [180].…”

A comprehensive review of MXenes as catalyst supports for the oxygen reduction reaction in fuel cells

“…10 Due to their excellent electrical conductivity properties, MXenes were initially studied as energy storage materials for lithium-ion batteries [11][12][13][14][15][16][17] and supercapacitors. [18][19][20][21][22][23] In the past few years, MXenes have been explored and studied for use in many other applications, such as in electronics, [24][25][26][27] biomedicine, 28,29 sensors, [30][31][32][33][34][35][36][37] biosensors, [38][39][40][41][42][43][44] photothermal conversion, [45][46][47] water purification, [48][49][50][51] and even in the field of catalysis. [52][53][54][55][56][57]…”

Recent Advanced on the MXene–Organic Hybrids: Design, Synthesis, and Their Applications

“…Later, Neampet [112] and co-workers further enriched the sensor applying range by preparing a lactate oxidase immobilized on Pt//PANI/Ti 3 C 2 T x MXene hybrid for a modified screen-printed carbon electrode, which shows good response to H 2 O 2 and lactate. Besides, oxygen-containing volatile organic compounds, such as ethanol and acetone, could be detected by chemosensitive sensors, which were made by fluoroalkyl silane molecules modified Ti 3 C 2 T x [113]. The synergy of the strong adsorption energy of ethanol on Ti 3 C 2 T x -F and the local structure deformation contributed to the high sensitivity, good repeatability as well as long-term stability.…”