Table 1 Performance comparison of ZnO-based pH sensor with those reported previously
Sensing layer | pH range | Sensitivity (mV/pH) | Response time (s) | Electrolyte volume | References |
|---|---|---|---|---|---|
ZnO thin film | 2–12 | 38 | – | Immersed in electrolyte | [88] |
ZnO NRS/NTs | 4–12 | 45.9 | – | Immersed in electrolyte | [34] |
ZnO/Ta thin film | 1.3–12 | 41.56 | – | Immersed in electrolyte | [89] |
ZnO thin film | 4–12 | 49.35 | – | Immersed in electrolyte | [90] |
InGaZnO thin film | 3–10 | 59.2 |  < 300 | Immersed in electrolyte | [91] |
ZnO thin film | 2–9 | 43.71 | 29 | 5 mL | [26] |
ZnO NW | 4–12 | 45.89 |  < 0.5 | 5 mL | [3] |
Al-doped ZnO NW | 2–12 | 50.3 |  < 0.5 | 5 mL | [3] |
In−Ga−ZnO nanoparticle/Si Nanowire | 2–10 | 50 | 60 | Immersed in electrolyte | [92] |
ZnO nanotube | 4–12 | 45.9 | 300 | Immersed in electrolyte | [34] |
ZnO nanorod | 4–12 | 28.4 | 300 | Immersed in electrolyte | [34] |
Passivated intrinsic zinc-oxide nanorod | 4–12 | 44.01 | – | Immersed in electrolyte | [90] |
ZnO thin film | 2–9 | 43.71 | 29 | 5 ml | [26] |
CO/CZO heterostructure | 3–12 | 52.2 | 19 | Immersed in electrolyte | This work |
5% Co-doped ZnO | 3–12 | 42.7 | 22–23 | Immersed in electrolyte | This work |