Low-temperature NO₂ gas sensing by delafossite-structured AgFeO₂ nanograins

In this work, silver ferric oxide (AgFeO₂) nanoparticles have been successfully synthesized using the co-precipitation method and characterized with various techniques. Highly porous, grain-like AgFeO₂ nanoparticles were prepared. Furthermore, this work explores and for the first time proposes the possibility of using low-cost AgFeO₂ nanoparticles with a delafossite structure for the low-temperature detection of nitrogen dioxide (NO₂) gas. AgFeO₂ nanoparticle powder was characterized using X-ray diffraction (XRD). It discloses the delafossite structure indicating the presence of both rhombohedral and hexagonal structures having an average crystallite size of 47 nm. The field emission scanning electron microscopy (FE-SEM) and energy-dispersive spectroscopy (EDS) study give the idea about dense distribution nanoparticles and confirm the elemental composition of AgFeO₂, respectively. Transmission electron microscopy (TEM) shows that grain-like nanostructures have a particle size in the range of between 50 and 80 nm. The specific surface area was calculated by Brunauer–Emmett–Teller (BET), and it was found to be 31.9353 ± 0.1551 m²/g. It is found that the AgFeO₂ gas sensor shows high selectivity to words NO₂ gas at 8 ppm gas concentration at an operating temperature of 50 °C.