Surface functionalized MXene ink-enabled washable smart e-textiles with exceptional gas sensing properties

Abstract

Electronic textiles (e-textiles) that sense physical stimuli and toxic gases, exhibit Joule heating capabilities, and enable information transmission hold great promise for advancing personalized healthcare. Titanium carbide MXene, Ti3C2Tx (Tx = -OH, -O, -F, etc.), has shown huge potential for creating such e-textiles owing to its twodimensional morphology, high electrical conductivity, reactive surface characteristics, and facile integration into textiles by solution-based approaches. However, MXene nanosheets' poor oxidation stability and weak adhesion to textile fibers raise concerns about MXene-based e-textiles' washing durability. Further, the toxic gas sensing abilities of MXene-based e-textiles have hardly been realized. To overcome these challenges, MXene surface is functionalized with dopamine-conjugated carboxymethyl cellulose ligands (CMC-DA-MXene), which protect MXene from oxidation and initiate strong adhesive interactions with textile fibers. Despite the presence of CMC-DA intercalants, the CMC-DA-MXene nanosheet assemblies maintain good electrical conductivity; as a result, etextiles exhibited excellent Joule heating and tactile/flex sensing properties. Additionally, the unique ability of CMC-DA ligand to selectively interact with NO2 gas molecules and humidity through the catechol head and carboxymethyl cellulose tail, respectively, enables the incorporation of NO2 and humidity sensing capabilities into CMC-DA-MXene e-textiles. The gas/humidity sensing mechanism is explained using density functional theory calculations. Overall, the results provide a foundation for realizing multifunctional MXene-based e-textiles that are oxidation-resistant and washable.