Improved NO₂ Sensing Performance of Ternary Nanocomposites Based on Au-doped Co₃O₄/CuO

To enhance the poor sensing capabilities of traditional p-type metal oxide semiconductor sensors, a novel gas sensor was designed with Co 3 O 4 /CuO heterostructure modified by glutathione (GSH)-reduced gold (Au), which was characterized by different analyses. The experiments showed that the 0.5[Formula: see text]wt.% Au–Co 3 O 4 /CuO gas sensor exhibited excellent sensing performance with a response value of up to 28.3 for 3[Formula: see text]ppm NO 2 at a relatively low operating temperature ([Formula: see text]C). Besides, it demonstrated a linear relationship between detection concentration and response value, displayed good selectivity for NO 2 , showcased stability and exhibited repeatability. Moreover, the sensor revealed the ability to resist humidity at the optimal temperature. Finally, we proposed a gas sensing mechanism to explain the enhanced NO 2 detection performance of the sensor, attributed to the heterojunction structure between Co 3 O 4 /CuO and the catalytic properties of Au. This led to an increase in adsorbed oxygen, as confirmed by XPS characterization. Therefore, the 0.5[Formula: see text]wt.% Au–Co 3 O 4 /CuO ternary nanocomposite gas sensor is deemed to be a highly effective sensing material that can be utilized to detect NO 2 gas in real-life applications.