Highly sensitive and stable phenyl hydrazine chemical sensors based on CuO flower shapes and hollow spheres

Abstract

Chemical sensors are needed to develop efficient sensing systems with high flexibility, and low capital cost for controlled recognition of analytes. Herein, we report a highly sensitive, low cost, simple chemical sensor based on flower shape and hollow sphere CuO. Following the precipitation process, FESEM images revealed that CuO nanosheets are grown in high density and organized in a proper manner to give a flower shape structure; however, following the hydrothermal method in the presence of urea, the cage like micro structures CuO hollow spheres have been discovered. XRD revealed that the grown CuO has a single-crystalline phase of a monoclinic system. The resistivity of CuO hollow spheres (1.93 × 10⁶ Ω m) is ∼100 times higher than flower shape CuO (2.2 × 10⁴ Ω m). The prepared CuO flower shapes and hollow spheres have been evaluated for the detection and quantification of phenyl hydrazine. The findings indicate that CuO hollow spheres and flowers exhibited good sensitivity (0.578 and 7.145 μA cm⁻² mM⁻¹) and a lower limit of detection (LOD = 2.4 mM) with a linear dynamic range (LDR) of 5.0 μM to 10.0 mM and rapid assessment of the reaction kinetics (in the order of seconds). The designed flower shape CuO sensing system is 12 times more sensitive than CuO hollow spheres. To the best of our knowledge, the measured sensitivity ∼ 7.145 μA cm⁻² mM⁻¹ of CuO flower shapes is found to be among the highest sensitivity values reported for phenyl hydrazine up to now.