Self-reduction of gold@platinum bimetallic nanoparticles on Ti3C2Tx MXene nanoribbons coupled with hydrogel and smartphone technology for colorimetric detection of silver ions

In recent years, numerous colorimetric methods have been developed for the detection of silver ions (Ag+), yet there remains a need for a simple, sensitive, real-time and quantitative sensing platform. Herein, Ti3C2Tx MXene nanoribbons (Ti3C2TxNRs) were utilized as the carrier material, and gold@platinum (Au@Pt) bimetallic nanoparticles were decorated onto the Ti3C2TxNR surface, for the first time, via a facile self-reduction method. The resulting Au@Pt–Ti3C2TxNR nanohybrid exhibited excellent catalytic activity, facilitating the oxidation of 3,3′,5,5′-tetramethylbenzidine, a colorless substrate, to generate a blue product (oxTMB), displaying prominent peroxidase-like activity. In the presence of Ag+, a remarkable inhibiting effect was observed on the catalytic activity of the Au@Pt–Ti3C2TxNR nanohybrids, effectively halting the generation of oxTMB. Based on this, the as-obtained Au@Pt–Ti3C2TxNR nanozyme was then utilized to develop a novel colorimetric sensing platform for Ag+ detection, with a low detection limit of 1.57 nM and a wide linear detection range from 5.0 nM to 9.0 μM. In addition, by combining the unique advantages of hydrogel materials and smartphone technology, a simple, real-time and quantitative platform for Ag+ monitoring was constructed, highlighting its potential for practical applications in Ag+ detection.