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- Title
A dual-functional flexible sensor based on defects-free Co-doped ZnO nanorods decorated with CoO clusters towards pH and glucose monitoring of fruit juices and human fluids.
- Authors
Hilal, Muhammad; Yang, Woochul
- Abstract
Herein, ZnO nanorods were doped with Co and decorated with CoO clusters through an in situ technique to create a CoO/Co-doped ZnO (CO/CZO) heterostructure at low temperatures (150 °C) on a flexible PET substrate. In the CO/CZO heterostructure, the Co dopant has a low energy barrier to substitute Zn atoms and adsorb over oxygen atoms and their vacancies. Therefore, it decreased the charge density (ND = 2.64 × 1019 cm−3) on non-active sites of ZnO and lowered the charge transfer resistance (317 Ω) at Co-doped-ZnO/electrolyte interface by suppressing the native defects and reducing the Schottky barrier height (− 0.35 eV), respectively. Furthermore, CoO clusters induced a p-n heterostructure with Co-doped ZnO, prevented corrosion, increased the active sites for analyte absorption, and increased the ultimate tensile strength (4.85 N m−2). These characteristics enabled the CO/CZO heterostructure to work as a highly sensitive, chemically stable, and flexible pH and glucose oxidation electrode. Therefore, CO/CZO heterostructure was explored for pH monitoring in human fluids and fruit juices, demonstrating a near-Nernst-limit pH sensitivity (52 mV/pH) and fast response time (19 s) in each human fluid and fruit juice. Also, it demonstrated high sensitivity (4656 µM mM−1 cm−2), low limit of detection (0.15 µM), a broad linear range (0.04 mM to 8.85 mM) and good anti-interference capacity towards glucose-sensing. Moreover, it demonstrated excellent flexibility performances, retained 53% and 69% sensitivity of the initial value for pH and glucose sensors, respectively, after 500 bending, stretching, and warping cycles. Highlights: Low-temperatures growth of defect-free CoO/Co-doped ZnO heterostructure. Doping lowered ND on non-active sites, ɸB, and Rct at ZnO/electrolyte interface. CoO prevent corrosion, increase active sites and enhance ultimate tensile strength. Obtained high sensitivity 52 mV/pH for pH and 4656 µM mM−1 cm−2 for glucose sensors Both potentiometric and amperometric mechanism of the heterostructure is proposed.
- Subjects
FRUIT juices; TENSILE strength; ZINC oxide; GLUCOSE; FLEXIBILITY (Mechanics); NANORODS; POLYETHYLENE terephthalate
- Publication
Nano Convergence, 2022, Vol 9, Issue 1, p1
- ISSN
2196-5404
- Publication type
Article
- DOI
10.1186/s40580-022-00305-x