Hybrid liquid crystalline zinc phthalocyanine@Cu2O nanowires for NO2 sensor application

[Display omitted] •An organic/inorganic hybrid NO2 sensor was proposed by decorating the surface of Cu2O nanowires with (C6S)8PcZn.•A comparison of UV–vis absorption profiles presented the optical properties of Cu2O nanowires and (C6S)8PcZn film in the hybrid structure.•DFT calculations highlighted the importance of S atoms in the (C6S)8PcZn chains for electronic states of the surface.•A p-p isotype heterojunction between (C6S)8PcZn and Cu2O was investigated with conductometric NO2 measurements.•The hybrid sensor enhanced NO2 sensing under humid airflow contrary to the individual performances of (C6S)8PcZn film and Cu2O nanowires. A novel organic-inorganic hybrid conductometric NO2 sensor has been introduced by depositing liquid-crystalline zinc oktakisalkylthiophthalocyanine [(C6S)8PcZn] on the surface of Cu2O nanowires. Cu2O nanowires were synthesized by electrochemical anodization of Cu films on glass substrates. Surface structures of bare Cu2O and (C6S)8PcZn@Cu2O nanowires hybrid structures were monitored by scanning electron microscope (SEM). UV–vis spectrophotometer measurements revealed the heterostructure formation by comparing the absorption profiles of bare Cu2O nanowires, (C6S)8PcZn thin film, and (C6S)8PcZn@Cu2O hybrid nanowires. The interdigitated transducers (IDT) were used for conductometric gas measurements. The sensing properties of all samples were investigated towards 500 ppb, 1 ppm, 2 ppm, and 5 ppm NO2 under dry airflow in 30 °C, 50 °C, 100 °C, and 150 °C. The measurements at 150 °C were repeated for (C6S)8PcZn film and hybrid sample using the same concentrations of NO2 gas under 38 % relative humidity airflow. In addition, selectivity of hybrid sensor was confirmed with carbon monoxide (CO), hydrogen (H2) and ethanol (C2H5OH) measurements. Our density functional theory calculations indicate that S atoms play a crucial role in improving the sensor response. The sensing properties and sensing mechanisms of samples were compared and discussed.