Facile Fabrication of Heterogeneous Olfactory Sensing Array via Thermal Manipulation of A Single Sr─Fe─O Perovskite Precursor

The electronic nose aims to emulate the olfactory capabilities of osmatic animals, utilizing olfactory sensing array with different sensing characteristics to perceive odors. However, the separate precursors and preparation methods of sensing materials pose challenges in the fabrication of an olfactory sensing array. In this work, the customization of the surface crystal phase of Sr─Fe─O materials (SFO) is demonstrated through the control of annealing temperature, enabling the simple fabrication of an olfactory sensing array using a single precursor. Significantly, the SFO materials exhibit diverse proportions of surface crystal phases, showcasing varied selective characteristics toward volatile organic compounds (VOCs). The materials also demonstrate remarkable responsiveness, linearity, and response/recovery times. Furthermore, this study unraveles the intricate gas-sensor mechanism through first principle calculations, revealing that Fe spin-down d band center of Sr 3 Fe 2 O 7 , located near the Fermi level, significantly enhances the binding strength of intermediates, leading to a higher response specifically to certain VOCs. Integrating these materials into a unified device, the sensor array quantitatively and discriminatively detected different VOCs. The results indicate that SFO materials hold tremendous potential as a promising and easily manufacturable olfactory material system.