SERS sensing chip based on Ti₃C₂/nano-Au@MA for ultrasensitive amine gas detection

In this paper, we propose a composite nano-microstructure comprising Ti3C2 and nanogold as a surface-enhanced Raman spectroscopy (SERS)-active substrate for the highly sensitive sensing of amine gases. The adsorption performance of Ti3C2 was tested by a quartz crystal microbalance (QCM) sensor. Excellent adsorption ability of Ti3C2 was observed for aniline, phenylenediamine, and diethylamine, with adsorption amounts exceeding 2210, 1740, and 970 ng cm(-2), respectively. The synergistic effect of the electromagnetic properties of Ti3C2 and nano-Au in the Ti3C2/nano-Au composite nanostructures was verified by finite-difference time-domain simulation. Partial chemical enhancement between Ti3C2 and aniline was verified by photocurrent tests. To achieve assay specificity, mercaptoacetaldehyde (MA) was adopted as a recognition probe. The Schiff base reaction between aldehyde groups and amino groups produces the -C=N- bond, with the Raman characteristic peak at 1635 cm(-1), enabling precise amine identification with the SERS chip. To obtain the Ti3C2/nano-Au@MA SERS sensing chip, nano Au was deposited on an indium tin oxide substrate using the chronoamperometric method, followed by nano-Au aldolization modification through Au-SH interactions and the spin-coating of a Ti3C2 film layer. Due to the high affinity of Ti3C2 for amine molecules and the low SERS background signal of MA and Ti3C2, the SERS spectra could be used for ultra-sensitive detection of amines. Three amine gases, i.e. aniline, p-phenylenediamine, and diethylamine, were detected quantitatively using the intensity ratiometric method on the functionalized Ti3C2/nano-Au@MA SERS sensor chip. The detection limits were 1, 1, and 20 parts per billion, respectively. By identifying the characteristic fingerprint peaks and comparing the relative intensity of the -C=N- characteristic peak, quantitative analysis of the components of aniline and p-phenylenediamine mixed gas was accomplished. These findings demonstrate that the Ti3C2/nano-Au@MA SERS sensor chip offers a promising approach for the detection of amine gas molecules and holds potential for applications in environmental monitoring, disease diagnosis, and chemical analysis.