Fabrication of WO3 nanosheets with hexagonal/orthorhombic homojunctions for highly sensitive ozone gas sensors at low temperature

Given the persistent and detrimental impact of atmospheric ozone (O 3 ) on human health, achieving high-sensitivity detection of ozone at low temperatures is crucial for mitigating its harmful effects. Here, by hydrothermal synthesis and annealing, hexagonal and orthogonal WO₃ (h/o-WO 3 ) homojunction nanosheets were prepared and used as high-performance O 3 sensors. The results showed that the optimal operating temperature of the h/o-WO 3 sensor is 120 °C, the response value to 3.0 ppm ozone is 320.8, and the detection limit is 40 ppb. The mechanism shows that the homojunction structure increases the depletion layer thickness and carrier separation, which facilitates ozone decomposition and significantly enhances the ozone sensing performance. This study provides a novel approach for the preparation of high sensitive low temperature ozone sensing materials. • Hydrothermal synthesis and annealing used to prepare h/o-WO₃ homojunction nanosheets . • The sensors detected ozone with a high response of 320.8 at 3 ppm and a low limit of 40 ppb at 120 °C. • Homojunction boost charge separation and ozone decomposition, increasing sensor sensitivity.