Au anchoring on 3D hierarchically porous Ti3C2Tx MXene aerogels for enhanced selectivity, response and kinetics in room-temperature trimethylamine sensing

Abstract

This study fabricated a 3D Au-anchored Ti₃C₂T_x MXene/sodium carboxymethylcellulose aerogel with a hierarchical porous structure through a facile freeze-drying-assisted strategy. In situ redox-driven surface functionalization enables site-specific, uniform anchoring of Au NPs on MXene. The optimized AMC aerogel exhibits a high selectivity of 3.88 and an ultrahigh sensing response of 90.7% at 100 ppm of TMA at room temperature, outperforming most reported MXene-based TMA sensors. It also exhibits excellent long-term stability (10.4% response attenuation over 60 days) and drastically shortened response/recovery time (from 387/682 s to 40.2/162.8 s). Additionally, AMC aerogel is validated for real-time monitoring of seafood (fish and shrimp) freshness by tracking spoilage-related TMA release, providing a promising platform for TMA-based clinical diagnostics. The high TMA sensing performance stems from the synergistic effect between a 3D hierarchical porous structure that provides abundant active adsorption sites and rapid gas diffusion channels, and Au anchoring that modulates the electronic structure of the composite by precisely tuning the d-band center, optimizing Lewis acid-base pairing, and facilitating selective TMA adsorption and fast interfacial charge transfer. This work presents a novel structural design strategy and fundamental insights into high-performance MXene-based aerogels for room-temperature detection of volatile organic compounds.