For many years, gas sensors have attracted great interest due to their applications in various fields such as medical diagnosis, environmental monitoring, worker safety, and food quality control. For these applications, ideal gas sensors should have high sensitivity and selectivity for tracking targets, fast response/recovery capabilities, low energy consumption, and cost-effectiveness.

Although many sensors have been reported to have rapid response/recovery, high sensitivity, and low cost under high operating temperatures or light activation, rapid response/recovery, especially sensitivity in the billionth range, is often still insufficient under low energy consumption conditions.

Metal oxide semiconductors (MOS) are widely used as sensing materials due to their low cost and good chemical stability. However, the inherent low carrier concentration limits their effective operation at room temperature (RT), typically requiring external light activation or thermal energy to excite carriers and achieve high sensitivity in gas detection. To meet the market demand for gas sensors, developing sensing materials that are independent of external heat and light activation has become a hot topic in the field of chemical resistance gas sensors. Although common strategies mainly rely on noble metal modification and element doping to increase carrier concentration, from a cost-effectiveness perspective, efficient and simple methods are needed.

The design of double heterojunctions is a broad and effective strategy to improve electron hole separation in semiconductors, thereby increasing carrier concentration and enhancing the performance of related surface catalytic reactions. However, limited control over carrier transport may have an impact on the sensing performance of heterojunction based samples. In this regard, the normal method involves generating an internal electric field (IEF) to accelerate electron transfer, thereby improving the sensing performance of the target gas. However, the development of multi heterojunction structures still faces many challenges, such as potential barrier effects and poor interface contacts, which seriously hinder charge transfer efficiency. As an alternative to using IEF to accelerate charge transfer, constructing special chemical bridges will provide additional pathways for charge transfer; This will lead to improved electron hole separation, resulting in satisfactory sensing performance without external activation. In addition, exploring the fundamental mechanisms of interface chemistry and charge transfer in heterostructures is another important task.

Source: Sensor Expert Network