Room-temperature trimethylamine gas sensor with biomass carbon microtubule-grown SnO2 nanosheets for efficient assessment of fish freshness

The detection of trimethylamine (TMA) is important not only for assessing the quality of seafood products but also for monitoring the environment. Biomass-derived carbon materials have been used for gas-sensitive detection because of their environmental friendliness, abundance, diversity, and chemical stability. In this work, the green waste of groundsel fibers (GFs) was used as a substrate, and ultrathin SnO 2 nanosheets were successfully grown in situ on GFs via a simple hydrothermal reaction (SnO 2 /CGFs). The structures and morphologies of the materials were characterized to detect TMA gas at room temperature. Compared with pure CGFs, SnO 2 /CGFs showed satisfactory selectivity for TMA (500 ppm), higher sensitivity, and a response/recovery time of 5.5/3.3 s. The SnO 2 /CGF sensor exhibits good long-term stability and repeatability for the detection of TMA gas. It exhibits good linearity in measuring TMA gas in the concentration range of 5–200 ppm with a theoretical detection limit of 0.475 ppm and monitored the spoilage process of sea bass at room temperature. The improved gas-sensitive performance of SnO 2 /CGFs is attributed to the unique microstructure, heterojunction formation, and abundance of oxygen species of SnO 2 on carbon tubes of biomass grown in situ.