NO2 sensing with a part-per-billion limit of detection using Fe2(MoO4)3 hollow microspheres synthesized by a bubble template method

High-performance NO 2 sensors are in high demand for various areas, ranging from automobiles and industrial processes to environmental monitoring. Nanomaterials with a high surface area are widely used to fabricate high-performance NO 2 sensors. A universal and important issue for nanomaterial based sensors is aggregation between neighboring nanoparticles. In this study, the non-agglomerated hollow microspheres Fe 2 (MoO 4 ) 3 were synthesized by a bubble template method and agglomerated nano Fe 2 (MoO 4 ) 3 were also synthesized for comparative purposes. There is a 170 % increase in response (NO 2 : 1 ppm) when Fe 2 (MoO 4 ) 3 crystallized in non-agglomerated hollow microspheres, rather than agglomerated nanoparticles. The hollow microspheres Fe 2 (MoO 4 ) 3 were characterized to be a promising NO 2 sensor with ppb-level detection, long-term stability, high selectivity, and good reproducibility. The hollow structure results in superior NO 2 sensing properties by providing abundant sensing surfaces for gas adsorption, diffusion, ionization, and reduction. A very promising NO 2 sensor with ppb level detection was developed using Fe 2 (MoO 4 ) 3 hollow microspheres synthesized by a bubble template method. • A very promising NO 2 sensors with ppb level detection were developed. • Fe 2 (MoO 4 ) 3 with hollow microspheres were synthesized by a bubble template method. • There is a 170 % increase in response when Fe 2 (MoO 4 ) 3 crystallized in microspheres. • The hollow microspheres with thin permeable shell layers are advantages in sensing.