Construction of a GdVO₄-In₂O₃ n-n heterojunction enables ppb level triethylamine detection at low temperatures

Currently, triethylamine gas sensors based on semiconducting metal oxides generally suffer from issues such as high operating temperatures and relatively high detection limits (typically at the ppm level). To address the aforementioned issues, this study successfully synthesized GdVO₄-In₂O₃ composite materials using a two-step hydrothermal method. Benefiting from the formation of an n-n heterojunction and the introduction of oxygen vacancies, this composite material exhibits outstanding gas-sensing performance at lower operating temperatures. At an operating temperature of 80 °C, the sensor exhibits a response value of 5011 to 100 ppm triethylamine, representing 172.72 times and 43.35 times the response of pure GdVO₄ and In₂O₃, respectively. The operating temperature is correspondingly reduced by 68% and 55.56%. Additionally, the sensor exhibits a response value of 15.26 for triethylamine at concentrations as low as 50 ppb, with a linear fit determination coefficient of 0.995 within the 50–1000 ppb concentration range. Currently, research reports on GdVO₄-based gas sensors remain limited. This study successfully synthesized GdVO₄-In₂O₃ composite materials for the first time, providing an effective solution for low-temperature detection of triethylamine at the ppb level while expanding the research framework for GdVO₄-based gas sensors.