Room-temperature highly sensitive CO gas sensor based on Au-modified SnO₂/ZnO

To address the need for high-sensitivity carbon monoxide (CO) gas sensing at room temperature, a CO gas sensor based on Au-modified tin oxide/zinc oxide (SnO₂/ZnO) nanocomposites is fabricated. SnO₂ nanoparticles, ZnO nanosheets, and Au nanoparticles (AuNPs) were synthesized using sacrificial template, hydrothermal, and chemical reduction methods, respectively. The resulting nanocomposite was then drop-casted onto interdigitated electrodes and dried to obtain the CO gas sensor. The performance of the sensor was evaluated using a custom airtight chamber and a semiconductor parameter analyzer. The n–n heterojunction between SnO₂ and ZnO significantly increased oxygen vacancy in the composite material, enhancing surface chemisorption of oxygen. Moreover, the catalytic sensitization effect of AuNPs facilitated electron migration, while their inherent spillover effect promoted the activation of gas molecule interactions. Consequently, the sensor exhibited a high response (22.11%) to 70 ppm CO at room temperature, along with excellent stability, selectivity, and anti-interference capabilities. This work offers a promising approach for developing highly sensitive room-temperature gas sensors.