Pr2Sn2O7/NiO heterojunction for ultra-fast and low operating temperature to NO2 gas sensing

Abstract

The performance of NO2 sensors with low operating temperature, high selectivity, and high sensitivity is of importance in the gas sensing field. In this work, porous Pr2Sn2O7/NiO heterojunction was fabricated by solid-state reaction. We analyzed the phase composition, morphology, and chemical composition of Pr2Sn2O7/NiO using X-ray diffraction, scanning electron microscope, chemical element mapping, transmission electron microscope, and X-ray photoelectron spectrometer. The gas sensing result reveals that the Pr2Sn2O7/NiO possesses significantly improved performance toward NO2 than that of Pr2Sn2O7. The fast response time of 2 s and high response value of 27.4 were realized in 250 ppm NO2 at 180 ℃, promoting 17.5 times that in pure Pr2Sn2O7. According to the Hall effect measurement, the carrier type of Pr2Sn2O7/NiO composite is dominated by electrons, so the resistance of Pr2Sn2O7/NiO increases once it is exposed to strong oxidizing gas. The heterojunction and Ni2+ replace Pr3+ reduce the sensor's operating temperature, providing a new strategy for developing a low-energy consumption device. Our work provides new insight into potential development for Pr2Sn2O7/NiO based heterojunction.