Using a protrusion sapphire substrate to synthesize ZnO nanoflower arrays and application of Cu decorated ZnO nanoflower arrays as a H2 and CO gas sensor

In this study, a straightforward method is proposed to grow ZnO nanoflower arrays, which will be utilized as gas sensors for detecting H-2 and CO gases. The process involves using the sol-gel method to create the ZnO thin films on a sapphire substrate with protrusion structure. These thin films are then annealed to serve as the seed layer for the subsequent growth of ZnO nanorods. For the synthesis of the ZnO nanorods, a 0.3 M solution containing C6H12N4 and Zn(CH3COO)(2) - 2H(2)O was employed as the precursor, and the hydrothermal method was used at 90 degrees C for a synthesis time of 60 min. Due to the unique protrusion structure of the ZnO seed layer, the ZnO nanorods grew perpendicular to it, resulting in the formation of the ZnO nanoflowers. Furthermore, the ZnO seed layer's matrix structure enables the growth of the ZnO nanoflowers in an orderly array pattern. For the further enhancement of the sensing properties of the gas sensor, a deposition method was used to decorate the Cu nanomaterials on the ZnO nanoflower arrays. The undecorated and Cu-decorated ZnO nanoflower arrays were proceeded to fabricate devices utilizing complemented by an interdigital upper electrode. Subsequently, the gas-sensing performance of both sensor types was compared concerning their ability to detect H-2 and CO gases. The findings in this research conclusively indicate that sensors fabricated using the Cu-decorated ZnO nanoflower arrays exhibited a remarkable enhancement in gas-sensing properties when compared to the device using the undecorated ZnO nanoflower arrays, particularly for detecting H-2 and CO gases. These results demonstrated that the Cu-decorated sensors had substantially higher response rates and faster response times during the gas-detecting processes.