Hydrothermal synthesis of hierarchical nanoparticle-decorated ZnO microdisks and the structure-enhanced acetylene sensing properties at high temperatures

Nanoparticle-decorated ZnO microdisks showing a hierarchical structure were successfully synthesized through a citric acid-assisted hydrothermal process. The ZnO microdisks had a hexagonal wurtzite structure with high crystallinity. Sensors based on these microdisks exhibited high response values, fast response–recovery, good selectivity and long-term stability to 1–4000 ppm acetylene at 420 °C. In addition, even 1 ppm acetylene can be detected with high response (S = 7.9). The hierarchical structure can facilitate to fix the ZnO nanoparticles leading to a less aggregated configuration, which is expected to contribute much to the excellent acetylene sensing properties at high temperatures.