Electrode-Dependent Gas Sensing Behavior of CNT-TiO₂ Hybrids for Ethanol Detection

Abstract

The development of gas sensors with high sensitivity and reliable response characteristics is essential for detecting volatile organic compounds (VOCs) such as ethanol in industrial, medical, and environmental applications. Carbon nanotubes (CNTs) are promising materials for gas sensing due to their outstanding electrical, mechanical, and chemical properties; however, their practical performance is often limited by low response levels toward specific gases. In this study, CNTs were hybridized with titanium dioxide (TiO₂) to enhance their sensing performance toward ethanol. In addition, the influence of different metal electrodes on the sensing behavior of CNT-TiO₂ hybrid sensors was systematically investigated. The results show that TiO₂ hybridization significantly enhances the sensitivity of CNT-based sensors to ethanol, while the choice of electrode material strongly affects the electrical behavior and gas response characteristics. Although most electrodes primarily influence the response magnitude, certain electrodes, such as aluminum, exhibit distinctive response features. Furthermore, analysis of response and recovery times reveals notable electrode-dependent variations with no direct correlation to sensitivity, indicating that dynamic parameters provide complementary information. These findings highlight the potential of electrode engineering and multi-parameter response analysis to enhance response differentiation and support future gas discrimination strategies in CNT-TiO₂-based sensing platforms.