Titanium nitride sensor for selective NO₂ detection

Efficient detection methods are needed to monitor nitrogen dioxide (NO₂), a major NO_x pollutant from fossil fuel combustion that poses significant threats to both ecology and human health. Current NO₂ detection technologies face limitations in stability and selectivity. Here, we present a transition metal nitride sensor that exhibits exceptional selectivity for NO₂, demonstrating a sensitivity 30 times greater than that of the strongest interfering gas, NO. The sensor maintains stability over 6 months and does not utilize platinum or other precious metals. This notable performance has been achieved through preparation of highly active titanium nitride (TiN_x) nanoparticles with exceptionally large surface area and a high concentration of nitrogen vacancies. By contrast, a commercial sample of TiN shows no gas sensing activity. Such devices are potentially scalable for everyday NO₂ detection and demonstrate that robust high-performance gas sensors based on inexpensive metal nitrides without precious metals are leading candidates for environmental monitoring technologies.