Chemoresistive xylene sensor based on hollow praseodymium oxide nanospheres

•Hollow Pr12O22 nanospheres were applied to aromatic hydrocarbons detection.•The semiconductor presented a rare p-type behavior due to the Pr valence states.•The material showed higher selectivity to m-xylene than to benzene and toluene.•The sensor could detect low concentrations (5 ppm) of m-xylene.•Pr12O22 showed long-term stability, which is fundamental for a reusable sensor. Praseodymium oxide has already been explored in several applications within materials science. Yet, its use as a chemoresistive gas sensor has rarely been reported. Herein, we present the aromatic hydrocarbon sensing performance of monoclinic Pr12O22 nanospheres produced via a microwave-assisted solvothermal approach with a subsequent calcination step. Sensing tests were performed at temperatures ranging from 200 to 500 °C and under different relative humidity conditions, from 0 % to 93 %. At 400 °C and dry conditions, the sensor exhibits a response of ca. 50 % towards 200 ppm m-xylene, which is much higher than those to benzene and toluene. The sensor also reveals excellent sensitivity for concentrations as low as 5 ppm of m-xylene, even at high relative humidity, while maintaining stability and repeatability over several days. Furthermore, the Pr12O22-based sensor presents an unusual p-type behavior attributed to the mixed valence states of the rare earth metal. [Display omitted]