Preparation And Property Of One-dimensional ZnO Nanorod Sensors

Nano-ZnO is a versatile inorganic material. The surface electronic structure andcrystal structure are different from bulk ZnO since grain nanolized. ZnO exhibitedexotic property in thermal, electrical, magnetic, optical and other area. In this paper,we use hydrothermal synthesis to prepare two kinds of one-dimensional ZnO nanometerials: nanorods array and nanorods. These two kinds of materials have beenmade into ethanol gas sensors and uric acid biosensors, respectively. Theperformance of the sensors was studied.Firstly, ZnO seeds layer were prepared on Al2O3ceramic tube using zinc acetatesolution. Then, one-dimensional ZnO nanorod array were prepared on top of ZnOseeds layer using zinc nitrate, hexamethylenetetramine, polyetherimide, andammonia reaction system at100℃for12h. Scanning electron microscope testsobserved ZnO nanorod array was perpendicular to the substrate and had a goodmorphology. X-ray diffraction analysis showed that the product was crystallinitygood without presence impurities. Next, this ceramic tube was used to make into gassensors for ethanol sensitivity tests. Gas sensitivity tests showed that the operatetemperature of this sensor was about425℃. Goodsensitive response was get for1.5～25ppm of ethanol gas. With the concentration increased, the sensitivity valuewas also increased. Ddifferent types of gas tests showed that ethanol sensitivity wasthe highest and reached84.00%.Secondly, we used zinc nitrate, hexamethylenetetramine and ammonia reactionsystem prepared one-dimensional ZnO nanorods ditrctely under100℃for12h.Scanning electron microscope tests observed good uniformity of this material. X-raydiffraction analysis showed that the product was also crystallized well, and had nopresence impurities.Next, the ZnO nanorods solution was dropped onto the surfaceof the glassy carbon electrode to make a modified electrode of biosensor. This biosensor was used for uric acid sensitivity test. Cyclic voltammetry tests showedthat signal response of modified electrode is7.8times larger than bare glassy carbonelectrode, approximately. Cyclic voltammetry tests of different scan rate indicatedthat UA was spread to the electrode surface via diffusion. Cyclic voltammetry testsof different concentrations of UA showed that oxidation peak current and UAconcentration of2.5×10^-7～5.0×10^-6M had a good linear relationship. Differentialpulse voltammetry tests ingdicated its sensitivity was4.41×10^-6 M A^-1cm^-2.