Highly selective and sensitive xylene gas sensor fabricated from NiO/NiCr2O4 p-p nanoparticles

•Spinel-type NiCr2O4 based chemiresistive gas sensors were rarely reported for VOC gas detection working at moderate temperatures.•NiO/NiCr2O4 nanocomposites were successfully synthesized through a simple hydrothermal route and used as sensing materials.•The NiO/NiCr2O4 based gas sensor showed 37.2 times higher xylene response of 66.2–100 ppm compared with unmodified NiO sensor.•Superior xylene selectivity against other interfering gases such as ethanol (Sxylene/Sethanol = 11.8) and acetone (Sxylene/Sacetone = 10.2).•Ppb-level detection limit with a response of 1.2–50 ppb xylene indicated the potential use on the trace xylene detection.