Gansu Science and Technology News Media Center (Reporter: Zhang Yunwen) recently reported that researchers from Lanzhou University of Technology have made significant breakthroughs in the field of gas sensor research, with their findings featured on the cover of the prestigious journal, ACS Sensors, attracting widespread attention.
Gas sensors, as devices capable of sensitively identifying specific gases in the air, play a crucial role in environmental monitoring, industrial safety, and medical diagnostics. Their core components are typically made of metal oxide semiconductor materials, which act like a precise “electronic nose” that can detect various gases. However, the sensitivity of this “electronic nose” largely depends on a special structure within it known as “oxygen defects.”
So, what are “oxygen defects”? We can imagine metal oxide semiconductor materials as a neatly stacked block model, where oxygen atoms represent individual blocks. If there are vacancies in this block stack, missing oxygen atoms create what is known as an “oxygen vacancy.” Conversely, if extra oxygen atoms are packed into the stack, it is referred to as “interstitial oxygen.” For a long time, scientists have recognized that these “oxygen defects” can affect sensor performance, but the specific mechanisms have not been fully elucidated.
The research team at Lanzhou University of Technology employed an “in situ photoluminescence” technique to observe the dynamic changes of “oxygen defects” in gas sensors in real-time during operation. Through their observations, they discovered that different types of “oxygen defects” have varying impacts on sensor sensitivity. “Oxygen vacancy” defects can help the sensor adsorb more oxygen ions, thereby making the sensor more sensitive to gases, while “interstitial oxygen” defects suppress sensor sensitivity. By doping the materials with special elements such as holmium and praseodymium, they successfully controlled the type and quantity of “oxygen defects.” Experimental results indicated that the modified sensors exhibited significantly improved sensitivity to harmful gases like nitrogen dioxide.
The significance of this research lies in its clear revelation of the role of “oxygen defects” in metal oxide semiconductor gas sensors for the first time, providing important theoretical guidance and new ideas for the future design of more efficient and sensitive gas sensors.