Design and mechanism of highly-stability SnO2/g-C3N4 nanohybrid material humidity sensor

In this paper, a tin oxide (SnO₂)/graphitic carbon nitride (g-C₃N₄) hybrid humidity sensor enriched with O vacancies (O_v) and –NH_x functional groups is successfully developed, exhibiting high stability and low hysteresis. This SnO₂-loaded organic–inorganic hybrid structure effectively addresses the issue of hydrophilic-material loss in traditional organic polymers under high-humidity conditions, notably enhancing the stability of g-C₃N₄. The introduction of O_v considerably enhances water molecule–adsorption and electron-transfer capabilities, providing more adsorption sites for water molecules and facilitating their decomposition and proton conduction, thereby greatly enhancing the sensor's sensitivity and response speed. The reduction in water contact angle further increases the material's hydrophilicity, enhancing the sensor's response performance. The incorporation of –NH_x groups effectively shortens the response and recovery times. The SnO₂/g-C₃N₄ sensor exhibits remarkable stability, low response/recovery times (9/6 s), and low hysteresis (2.3%) across a relative humidity range of 11%–95%, hence demonstrating its great potential for practical applications. We believe this study not only provides new insights into the application of organic–inorganic hybrid materials in the field of humidity sensing but also establishes a solid theoretical foundation for the development of high-performance humidity sensors.