Morphology-Dependent Chemiresistive-Potentiometric Gas Sensing Properties of ZnO Nanorods for CH 4 and CO

In this study, one-dimensional ZnO nanorods sensing electrodes were grown in situ on the surface of the Ce 0.8 Gd 0.2 O 1.9 electrolyte to fabricate chemiresistive-potentiometric (C-P) bivariate sensors for the detection and identification of CH 4 and CO. Four C-P sensors were developed by adjusting the hydrothermal growth time of the nanorods. The effect of hydrothermal duration on the morphology of nanorods was examined. The C-P response to CH 4 and CO initially increased and then decreased with increasing hydrothermal duration. Similar variations in the response to the gas mixtures of CH 4 and CO with the hydrothermal duration were observed. The highest C and P response values for CH 4 , CO, and their mixtures were obtained at a hydrothermal duration of 1.5 h. The enhanced C-P sensing performance was discussed in terms of the defect density, the number of contact junctions, and the length of ZnO nanorods. Accurate differentiation of five different gases (CH 4 , CO, and three gas mixtures) with an identification accuracy of 100% was achieved by the array assembled with the ZnO-1.0 and the ZnO-1.5 sensors. Our findings demonstrate the morphology-dependent C-P sensing behaviors of ZnO nanorods and provide a facile and cost-effective method for the detection and identification of CH 4 and CO. C-P bivariate sensors were fabricated by growing ZnO nanorods on GDC electrolyte. The sensing performance were regulated by adjusting hydrothermal duration. Discriminative detection was achieved by the array based on ZnO nanorods. The morphology-dependent C-P sensing mechanism was discussed.