Recent Progress on Rare Earth Orthoferrites for Gas-Sensing Applications

Gas-sensing technology is crucial for the detection of toxic and harmful gases to ensure environmental safety and human health. Gas sensors convert the changes in the conductivity of the sensing material resulting from the adsorption of gas molecules into measurable electrical signals. Rare earth orthoferrite-based perovskite oxides have emerged as promising candidates for gas-sensing technology owing to their exceptional structural, optical, and electrical properties, which enable the detection of various gases. In this article, we review the latest developments in orthoferrite-based gas sensors in terms of sensitivity, selectivity, stability, operating temperature, and response and recovery times. It begins with a discussion on the gas-sensing mechanism of orthoferrites, followed by a critical emphasis on their nanostructure, doping effects, and the formation of nanocomposites with other sensing materials. Additionally, the role of the tunable bandgap and different porous morphologies with a high surface area of the orthoferrites on their gas-sensing performance were explored. Finally, we identified the current challenges and future perspectives in the gas-sensing field, such as novel doping strategies and the fabrication of miniaturized gas sensors for room-temperature operation.