Abstract
In the present work, tracing and Whatman papers were used as substrates to grow zinc oxide (ZnO) nanostructures. Cellulose-based substrates are cost-efficient, highly sensitive and environmentally friendly. ZnO nanostructures with hexagonal structure were synthesized by hydrothermal under microwave irradiation using an ultrafast approach, that is, a fixed synthesis time of 10 min. The effect of synthesis temperature on ZnO nanostructures was investigated from 70 to 130 °C. An Ultra Violet (UV)/Ozone treatment directly to the ZnO seed layer prior to microwave assisted synthesis revealed expressive differences regarding formation of the ZnO nanostructures. Structural characterization of the microwave synthesized materials was carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical characterization has also been performed. The time resolved photocurrent of the devices in response to the UV turn on/off was investigated and it has been observed that the ZnO nanorod arrays grown on Whatman paper substrate present a responsivity 3 times superior than the ones grown on tracing paper. By using ZnO nanorods, the surface area-to-volume ratio will increase and will improve the sensor sensibility, making these types of materials good candidates for low cost and disposable UV sensors. The sensors were exposed to bending tests, proving their high stability, flexibility and adaptability to different surfaces.
Highlights
In the recent years, a huge effort has been made to produce materials that can be used in different applications, such as nanoelectronics, optoelectronics, photonics, gas sensors, solar cells, photocatalysis, lab-on-paper for rapid diagnostic tests and antibacterial applications using flexible, biodegradable and green substrates, like cellulosic fiber-based substrates
By observing the values obtained it is thatfor forboth both types of cellulosic substrates the band gap value increased with the increase of synthesis temperature, with or substrates the band gap value increased with the increase of synthesis temperature, withwithout or without the use of treatment prior to
The zinc oxide (ZnO) nanorods arrays grown on cellulosic substrates were applied as Ultra Violet (UV) sensors, and for that only one condition from each substrate has been selected
Summary
A huge effort has been made to produce materials that can be used in different applications, such as nanoelectronics, optoelectronics, photonics, gas sensors, solar cells, photocatalysis, lab-on-paper for rapid diagnostic tests and antibacterial applications using flexible, biodegradable and green substrates, like cellulosic fiber-based substrates. Microwave synthesis has been successfully employed for several sources of nanomaterials, shortening the synthesis reaction time [6,8,14,15,16,17,18] As it is largely known, to synthesize a continuous ZnO layer using the hydrothermal synthesis method, it is imperative to use a seed layer [19,20]. In this sense, the use of different techniques for surface treatments have been reported by some authors to improve the surface wettability and adhesion. Morphological and optical characterization of the synthesized nanorod arrays, the materials were tested as UV sensors
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