Dual-functional Rh2O3 modification enhances the trace toluene detection performance of NiO based gas sensors

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Toluene, a common aromatic compound, is recognized by the International Agency for Research on Cancer (IARC) as a highly toxic carcinogen. This study synthesized a Rh 2 O 3 -modified Fe-NiO composite for detecting toxic toluene. Gas-sensing evaluations revealed that the material exhibits outstanding sensitivity toward toluene. The optimized Rh/FN7–0.5 sensor exhibited a high response of 92–100 ppm toluene at 225 ℃, with fast response/recovery (38/27 s), excellent selectivity, repeatability, and a low detection limit of 50 ppb. Fe doping increased the NiO surface area, facilitating the uniform dispersion of Rh 2 O 3 nanoparticles. The Rh 2 O 3 catalyst lowered the formation energy of oxygen vacancies, creating more active sites, and enhanced the surface reaction kinetics for toluene oxidation. The synergy between Fe doping and Rh 2 O 3 modification significantly improved the overall sensing performance.