Chemiresistive triethylamine sensor based on Rh2O3-loaded core-shell LaFeO3 porous spheres and DFT study to explain its behavior

Abstract

In this work, LaFeO₃ nanopowders with a core-shell structure were successfully synthesized using a facile hydrothermal method combined with wet impregnation to load varying amounts of Rh₂O₃ nanoparticles on the surface of core-shell spheres. Characterization results confirm that the synthesized Rh₂O₃-Fe₂O₃/LaFeO₃ samples have a core-shell structure with uniformly distributed Rh₂O₃ nanoparticles on the surface. In gas sensing studies, the sensor based on 2 at% Rh₂O₃-Fe₂O₃/LaFeO₃ core-shell spheres exhibited significantly enhanced performance (more than four times higher) for detecting triethylamine (TEA) compared to pristine Fe₂O₃/LaFeO₃ core-shell microspheres. At an operating temperature of 200°C, the sensor showed a response value of 237 for 100 ppm TEA with a very low detection limit (50 ppb, 1.2) and much faster response/recovery time (47 s/12 s). The performance improvement is due to changes in the potential barrier at the Rh₂O₃ and Fe₂O₃/LaFeO₃ interface, enhancing charge transfer. Additionally, based on first principles calculations, this work examines the adsorption energy and possible adsorption configurations of adsorbates. The Rh element acts as a negative charge center, which facilitates gas adsorption and reactions on the surface via a spillover effect. This study offers a promising candidate for TEA sensing and theoretical insights into high-performance sensor development.