Micro-Schottky Junction-Boosted Efficient Charge Transducing for Ultrasensitive NO2 Sensing

The detection of ultralow NO 2 for practical applications remains a significant challenge because the two critical characteristics of high sensitivity and good robustness are considerably unsatisfactory. Inspired by the classification of stimuli-receiving and signal-conveying for a stimuli-responsive procedure of a neuron in organisms, an internal micro-Schottky junction introduced into a chemiresistor is constructed as an efficient transduction strategy to boost the less concerned transducing stage for a further improvement in NO 2 sensing performance. The SnO 2 nanoflowers/reduced graphene oxide-based chemiresistor achieves a response of 10.5 toward 10 ppt NO 2 , with a record-breaking limit of detection of 0.73 ppt at room temperature as well as fast response and recovery times of 59 and 9 s at 10 ppt. Surprisingly, the sensor exhibits good robustness, including higher selectivity, long-term stability, and process stability. A comprehensive analysis of the electrical properties and energy band of inorganic materials reveals that the ultrahigh sensitivity and faster response/recovery are primarily related to the efficient transducing ability arising from the rapid electron transport and signal-amplifying effect contributed by micro-Schottky junctions. The concept of affiliating the sensing material modulation to the recepting and transducing stages and considering comprehensively provides a novel insight into the enhancement of gas sensing performance.