Carbon Monoxide Gas Sensor Based on Hydrothermally Synthesized Pd–CuO Nanorods/SnSe₂ Nanoflower Heterojunctions

Gas-sensitive materials play a decisive role in the performance of gas sensors, and room-temperature gas-sensitive materials can effectively reduce the power consumption of sensors. Materials such as metal oxides and selenides have good sensitivity characteristics at room temperature, making them the primary choice for constructing gas-sensitive materials. In this work, Pd–CuO nanorods and SnSe 2 nanoflower heterojunction composites were synthesized successfully. The characterizations confirmed that Pd–CuO nanorods were formed on the SnSe 2 layer. Compared with interfering gas, the Pd–CuO/SnSe 2 sensor exhibited the highest response to CO, which indicated that the selectivity of the sensor to CO was significantly enhanced. The sensor showed highly stable and reversible response recovery characteristics, with essentially no drift observed in the dynamic response to CO in three consecutive cycles. The sensor’s exceptional performance is mainly attributed to the heterojunction effect, which enhances charge transfer and CO adsorption. Furthermore, the response mechanism of the composite gas-sensitive material was further explored in conjunction with first-principles density functional theory.