Novel solution-gated transistor sensor-based SnO₂ epitaxial thin films grown by pulsed laser deposition for nitrite...

A solution-gate controlled thin-film transistor with SnO₂ epitaxial thin films (SnO₂-SGTFT) is successfully utilized for highly sensitive detection of nitrite. The SnO₂ films are deposited as channel materials on a c-plane sapphire (c-Al₂O₃) substrate through pulsed laser deposition (PLD), with superior crystal quality and out-of-plane atomic ordering. PtAu NPs/rGO nanocomposites are electrodeposited on a gold electrode to function as a transistor gate to further enhance the nitrite catalytic performance of the device. The change in effective gate voltage due to the electrooxidation of nitrite on the gate electrode is the primary sensing mechanism of the device. Based on the inherent amplification effect of transistors, the superior electrical properties of SnO₂, and the high electrocatalytic activity of PtAu NPs/rGO, the SnO₂-SGTFT sensor has a low detection limit of 0.1 nM and a wide linear detection range of 0.1 nM ~ 50 mM at V_GS = 1.0 V. Furthermore, the sensor has excellent characteristics such as rapid response time, selectivity, and stability. The practicability of the device has been confirmed by the quantitative detection of nitrite in natural lake water. SnO₂ epitaxial films grown by PLD provide a simple and efficient way to fabricate nitrite SnO₂-SGTFT sensors in environmental monitoring and food safety, among others. It also provides a reference for the construction of other high-performance thin-film transistor sensors.