Triple synergy of structure-size-catalytic enables highly sensitive NO₂ sensing at near room temperature

The urgent demand for trace NO₂ detection calls for innovative strategies to address the inherent limitations of metal oxide semiconductors (MOS), such as relatively small specific surface area and insufficient active sites. Herein, a structural-size-catalytic (SSC) synergistic effect was established by introducing Ni ions into the In₂O₃ using a metal-organic framework (MOF) templating method. This strategy intrinsically couples catalytic regulation with electronic structure modulation to optimize charge transport, while maximizing active sites through precise control over nanocrystal size and porosity. The optimized In₂O₃-6Ni sensor achieves a high response of 158.9 (2.5 ppm) and low limit of detection (LOD) of 25 ppb to NO₂ at 50 °C, improved anti-interference capability and moisture resistance. The practical application is further validated by integration into a microcontroller-based NO₂ alarm system. Experiments and simulations collectively verify the performance enhancement mechanism and validate the SSC effect as a universal design strategy for high-performance gas-sensing materials.