Printing assembly of flexible devices with oxidation stable MXene for high performance humidity sensing applications

Abstract

Transition metal carbides and carbonitrides MXenes have developed to be attractive nanomaterials for humidity-sensitive materials due to abundant hydrophilic active sites on their chemically active surfaces. Nevertheless, the low stability exhibited by MXenes in moist air or water limits their long-term storage and wide applications. This work proposes a composite of sodium ascorbate-decorated MXene (SA-MXene) by combining ascorbate ions with Ti3C2Tx MXene synthesized through a minimally intensive layer delamination (MILD) process. The synthesizing and decoration of MXene with SA to obtain SA-MXene had been shown to be a viable method for avoiding Ti3C2Tx MXene materials from oxidizing. The as-prepared SA-MXene was formulated as screen-printing ink with high stability and oxidation resistance despite being stored at ambient temperature after 30 days. Furthermore, a flexible humidity sensor was assembled by screen-printing technology with SA-MXene ink as the humidity-sensitive layer on the copper interdigital electrode prepared by the electrodeless deposition (ELD) process. Consequently, the SA-MXene sensor showed remarkable potential in humidity sensing with an ultrahigh relative capacitance response (131.4% to 97% RH) and rapid response time across a wide detection range. This work represents a promising strategy of developing SA-MXene to fabricate high sensitivity sensors derived from MXene.