H₂O₂-Treated ZnO Nanostructures for Humidity-Tolerant O₃ Chemiresistors Operated under Pulsed UV Light Modulation

Abstract

Severe humidity interference or even poison, especially at room temperature (RT), poses a challenge for the practical application of metal oxide semiconductor (MOS)-based chemiresistors for the monitoring of hazardous O3 vapor in a real humid air background, owing to the intrinsic hydrophilicity of general MOSs. Herein, we demonstrated that the humidity-tolerance performance of an ultraviolet (UV)-activated ZnO chemiresistor (operated at RT) toward O3 could be drastically improved by a facile H2O2 treatment. The onset of humidity poison starts around a relative humidity (RH) of 30% for a pristine ZnO chemiresistor, while the H2O2-treated ZnO (H2O2–ZnO) chemiresistor enables robust operation under a highly humid air background (90% RH). The response of ppb-level O3 under humid air could be further enhanced by pulsed UV light modulation (PULM) operation, and a high response (25 for 350 ppb of O3) could be achieved at RT and 90% RH, which is comparable or even higher than that of the state-of-the-art O3 chemiresistors (including the commercial MQ131 O3 sensor operated at 200 °C). The passivation of surface oxygen vacancy (VO) defects and reduction of grain size via H2O2 treatment probably enhance the humidity tolerance. Our work may shed light on the design of high-performance humidity-tolerant RT MOS chemiresistors for monitoring hazardous gases in ambient humid air.

Delafossite CuGaO2-Based Chemiresistive Sensor for Sensitive and Selective Detection of Dimethyl Disulfide

“…Due to the inherent hydrophilicity of general n-type MOSs (SnO 2 , WO 3 , ZnO, etc. ), preferential adsorption on the MOS surface easily occurs, which easily causes the response deterioration (or even poison) under the (high) humid air background. − , We have examined the humidity (0–90% RH) influence on the (10 ppm) DMDS responses at 140 °C. Strikingly, the CuGaO 2 sensor shows a satisfactory humidity resistance performance toward DMDS (∼13.4% decay from dry to 90% RH air; Figure a,b), and the good selectivity could be maintained under humidity conditions (Figures S8 and S9).…”

“…Third, due to inherent hydrophilicity of general MOS sensing materials (i.e., SnO 2 , ZnO, WO 3 , etc. ), humidity interference or even poison under high RH poses a challenge for real applications. − Exploring a high-performance DMDS sensor (combing the advantages of high response, low limit of detection (LoD), exceptional selectivity, good moisture resistance, etc.) is highly required for the practical application, but it still remains a challenge.…”