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Abstract

The development of high-performance humidity sensors based on nanotechnology has become critical for different applications. This work focuses on the fabrication and characterization of impedance-type humidity sensors based on graphitic carbon nitride, titanium dioxide, and carbon nanotubes. The prepared materials comprise g-C3N4, g-C3N4/TiO2, and g-C3N4/TiO2/CNTs, which have been synthesized through the co-precipitation method. The properties of the nanocomposites have been verified through different characterization techniques that confirm the phase composition and morphology. The humidity-sensing response of the prepared materials was tested within a humidity range of 11%–97% RH at different testing frequencies. The unique structure of synthesized materials combines the high surface area and hydrophilic active sites of both g-C3N4 and TiO2, in addition to the exceptional conductivity of CNTs. The g-C3N4/TiO2 humidity sensors demonstrated a significantly enhanced sensitivity of 2.2 MΩ/RH% compared to the bare g-C3N4-based humidity sensor, while the response and recovery are still challenging. The incorporation of conductive CNTs into the binary nanocomposite (g-C3N4/TiO2) improves the response kinetics with response and recovery times of 81 and 39 sec, respectively. Besides the improved response kinetics, the ternary structure also demonstrated excellent repeatability and low hysteresis.

Keywords

Humidity sensors, Nanocomposites, Grotthuss mechanism, Carbon nanotubes

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