Multi-functioning of CeO₂-SnO₂ heterostructure as room temperature ferromagnetism and chemiresistive sensors

Fabrication of novel materials with multi-functional active structure properties that can be used for gas sensing with augmented sensitivity, quick response-recovery rates and improved selectivity still present significant scientific challenges. The continuing interest in the design of such materials is driven by the increased emission of toxic gases in the industrial processes that result in detrimental threats to public health and environmental sustainability. Thus, the realisation in fabricating these materials for functional spin-based information processing devices remains indefinable due to numerous fundamental challenges. Consequently, in this work, we report on the room temperature chemiresistive gas sensing and ferromagnetism active structure based on the designed heterostructured CeO₂-SnO₂ nano-oxide interface. We elucidate that the optimised sensing material (CeO₂-SnO₂-300 °C), annealing at 300 °C, can detect ammonia (NH₃) gas at low concentration (parts-per-million, ppm) levels with rapid response-recovery times and improved sensitivity. The excellent selectivity towards NH₃ amongst other gases, such as CO, CH₄, H₂, H₂S, ethanol and NO₂, ensures adequate safety in detecting NH₃ hazards. Based on the NH₃ sensing characteristics, the tentative sensing mechanism was postulated. Moreover, the well-defined room temperature ferromagnetism (RTFM) was observed for mixed CeO₂-SnO₂-300 nano-oxide. The enhanced gas sensing response and RTFM were attributed to the concomitant structural improvements resulting from the high surface area, the relative concentration of oxygen vacancies and Ce³⁺ ions at the surface of CeO₂ for the CeO₂-SnO₂-300 °C sample. These findings provide additional insights into the design of novel multi-functional nanomaterials with striking magnetic ordering and enhanced gas sensing.