Zinc oxide (ZnO) nanowire by hydrothermal synthesis and its application to pH sensing

Abstract Recently, the importance of pH sensors in monitoring the pH of marine and water environments is growing. Although such sensors have been developed, existing fabrication methods have the challenge of requiring complex structures. Consequently, oxide-semiconductor pH sensors have been actively researched, with a particular focus on ZnO-based pH sensors that are economically viable and easy to manufacture and exhibit high sensitivity to subtle environmental changes. We propose an oxide-semiconductor pH sensor based on ZnO nanowires synthesized using a low-temperature hydrothermal method. The sensor is designed to have excellent sensitivity by achieving a high surface-to-volume ratio. ZnO nanostructure acted as a pH adsorption layer and the sensitivity by the nanostructure growth time of ZnO were evaluated. The nanostructure exhibited the highest sensitivity for a growth time 4 h, and response time and selectivity were also studied.