Self-reduce gold nanoparticles on Ti3C2Tx MXene nanoribbons to highly sensitive colorimetric determination of mercury ion and cysteine based on the mercury-motivated peroxidase mimetic activity

Ti3C2Tx MXene is the rising-star material recently and can exhibit unique self-reduction/adsorption ability towards some noble metal ions. Herein, Ti3C2Tx MXene nanoribbons (Ti3C2TxNR) decorated with gold nanoparticles (AuNPs) (Ti3C2Tx[email protected] nanohybrids) are prepared through a simple self-reduction method and used as a novel nanozyme for constructing a highly sensitive colorimetric sensing platform of mercury ion (Hg2+) on the basic of the mercury-motivated peroxidase mimetic activity: the peroxidase mimetic activity of Ti3C2Tx[email protected] towards 3,3′,5,5′- tetramethylbenzidine (TMB) is motivated and improved dramatically in the presence of Hg2+, inducing TMB to be oxidized and the solution color from colorless to dark blue that can be monitored. In addition, since the cysteine (Cys) molecules have the reducing property, which can reduce the TMB oxide (oxTMB) and further recover the color to colorless, a colorimetric sensing platform for Cys is also established. After optimizing several key parameters, the developed Ti3C2Tx[email protected] nanozyme-based colorimetric sensing platform exhibits superior sensing performances towards Hg2+ and Cys; meanwhile, the colorimetric detection of both analytes can also be achieved successfully by a smartphone. This work is expected to provide a simple approach to prepare MXene-based metal nanozyme and construct highly sensitive colorimetric sensing platform for Hg2+ and Cys.