Light activation is an effective method to improve sensor performance at room temperature (RT). This work realized the effective detection of trace-level NO2 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 NO2), 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.
Keywords: BiOI; Low detection limit; NO2 sensor; ZnO nanorods; fast speeds; visible light.