Nitrogen‐Doped Indium Oxide Electrochemical Sensor for Stable and Selective NO2 Detection

Efficient gas sensors are critical for environmental monitoring and industrial safety. While metal oxide semiconductor (MOS) sensors are cost‐effective, they struggle with poor selectivity, high operating temperatures, and limited stability. Electrochemical sensors, though selective and energy‐efficient, face high costs, and stability issues due to precious metal catalysts like platinum on carbon (Pt/C). Herein, a novel, cost‐effective electrochemical sensor using nitrogen‐doped indium oxide In2O3−xN2x/3Vx/3 (0.01≤x≤0.14), synthesized with varying nitriding times is presented. The optimized In2O3 N‐40 min sensor demonstrates a remarkable response current of 771 nA to 10 ppm nitrogen dioxide (NO2) at ambient temperature, with outstanding long‐term stability (over 30 days) and rapid response/recovery times (5/16 s). Compared to Pt/C sensors, it shows 84% and 67% reductions in response and recovery times, respectively, and maintains 98% performance after a month, versus 68% for Pt/C. This cost‐effective sensor presents a promising alternative for electrochemical gas sensing, eliminating the need for precious metal catalysts. The study pioneers the use of nonprecious metal electrochemical sensing materials, specifically nitrided In2O3, for NO2 detection. The In2O3 N‐40 min sensor exhibits a robust response (771 nA to 10 ppm NO2), exceptional stability (>30 days), and rapid recovery (5/16 s), outperforming Pt/C with 63 times higher selectivity and 98% longer stability.