Light activation is an effective method to improve sensor performance at room temperature (RT). This work realized the effective detection of trace-level NO 2 at RT under visible light by combining ZnO with the excellent photocatalyst BiOI. A 1.5 atom % BiOI−ZnO-based sensor under 520 nm light exhibited optimal sensing properties with the maximum responses (13.9 to 1 ppm NO 2 ), fast response/recovery time (66 s/47 s to 1 ppm), and a low detection limit of 25 ppb (theoretically 0.34 ppb). In the meantime, the sensor also possessed excellent selectivity, repeatability, and stability. The excellent properties were attributed to the high concentration of oxygen vacancies and the prolonged lifetime of photogenerated carriers. In addition, the observed photovoltaic effect of the sensor at RT indicated that the sensor held application prospects in the photovoltaic self-power field.

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A triethylamine gas sensor with humidity resistance, high selectivity, and high response is designed. Chromium oxide particles were prepared by heating them in a water bath at 80 °C. Pt/Cr2O3 nanoparticles were obtained by sodium borohydride reduction. The structure morphology of nanoparticles was characterized by some methods. The gas response test results showed that the modification of Pt improved the response value and selectivity of Cr2O3 to triethylamine. It was found that Cr2O3–2Pt nanoparticles had the best performance, and at the optimum operating temperature of 160 °C, its response value reached 200, 68 times that of Cr2O3 (S = 2.95). In addition, the modification of Pt made Cr2O3–2Pt nanoparticles had a wide range of humidity applications. The mechanism of gas response is explained by using the Schottky barrier and hole accumulation layer model of Pt and Cr2O3 contact and energy band theory.