High-performance and humidity-resistant NO2 gas sensors using ZnO/SnO2 Nano-heterostructures: Experimental and DFT study

We report a precisely controlled two-step hydrothermal synthesis of stannic oxide (SnO 2 ) nanoparticle-decorated zinc oxide (ZnO) nanorods and a comprehensive study combining experimental analysis with Density Functional Theory (DFT) calculations to explain the improvement mechanism of NO 2 sensing. The optimized ZnO/SnO 2 sensor shows a significantly enhanced response of 249.9 s to 5 ppm NO 2 at 150 °C, a temperature particularly lower than that of many conventional metal oxide sensors, with fast response/recovery times (77/80 s) and outstanding selectivity. Importantly, the sensor demonstrates dynamic performance in humid environments and exceptional long-term stability. DFT calculations disclose that the heterojunction formation enables stronger NO 2 adsorption ( E ads  = −1.0 eV) and greater charge transform which is confirmed by density of states analysis. This study provides not only a high-performance sensor candidate for real-world NO 2 detection but also a profound mechanistic insight through the synergy of experimental besides theoretical approaches.