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

Abstract 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 In₂O_3−xN_2x/3V_x/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.