Defect-Modified and Surface-Activated Ni-Doped ZnO/ZIF-8 Core/Shell Nanostructures for Ammonia Detection in Soil

High Resolution Image Download MS PowerPoint Slide Detecting hazardous gases, especially ammonia (NH 3 ), in soil is vital for ensuring environmental health and food safety. Zinc oxide (ZnO) is a widely studied material for gas sensing, particularly for detecting NH 3 . However, its practical application is hindered by poor sensitivity, unreliable selectivity, and poor resistance to humidity in a complex soil environment. We present a strategy to enhance the NH 3 -sensing performance of ZnO by synthesizing a nickel (Ni)-doped ZnO/zeolitic imidazolate framework (ZIF)-8 core/shell nanostructure. The resulting Ni-doped ZnO/ZIF-8 sensor exhibited significantly improved sensitivity (limit of detection (LOD) of 0.087 ppm and sensitivity of 10.1 × 10 –3 ppm –1 ) and selectivity toward NH 3, as well as resistance to humidity. To elucidate the mechanisms underlying sensing enhancement, we conducted comprehensive investigations using density functional theory (DFT) calculations and multiscale characterizations. Our findings highlight the crucial roles of defect modulation upon Ni doping and surface activation upon ZIF-8 coordination in enhancing carrier density, adsorption efficiency, and interferent filtering, which improve the overall NH 3 -sensing performance in soil. Our research also demonstrates not only how to fabricate gas sensors with enhanced sensing performance and practical application but also how integrating experimental and computational approaches can facilitate the rational design of sensors.