Exploring rational and feasible strategies to boost the gas sensing performance of metal oxide semiconductor (MOS) has attracted a growing concern because it is an inevitable path for advanced gas sensor. Herein, a Bi2O3 and Pt co-modification approach was proposed to upgrade the triethylamine (TEA) sensing performance of In2O3. To expound it, a series of hollow spheres (HSs) with different compositions including In2O3, Bi2O3-modified In2O3 (Bi2O3/In2O3), and Bi2O3 and Pt co-modified In2O3 (Pt/Bi2O3/In2O3) were prepared through a solvothermal-calcination route combined with subsequent chemical reduction. After the evolution from In2O3 to binary Bi2O3/In2O3 and ternary Pt/Bi2O3/In2O3 composites, the sensor exhibited a persistently boosted sensing performance to TEA, particularly of higher sensitivity (increased from 0.0219 to 0.0369 and 1.0319/ppm within 1–30 ppm), better selectivity (STEA/Methane increased from 17.6 to 23.7 and 257.2), and faster response speed (response time decreased from 7 to 3 and 1 s for 100 ppm TEA). Additionally, the best Pt/Bi2O3/In2O3 sensor also presented good repeatability and stability. The sensitization effects of Pt and Bi2O3-In2O3 p-n heterojunction were discussed in detail.
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