Soft-lithographically line-patterned In-doped ZnO quantum dots with hydrothermally grown ZnO nanocolumns for acetone detection

We introduced a new approach to enhance the sensing performance of sensors based on metal oxide semi-conductors. We synthesized In-doped ZnO quantum dots (IZO QDs) by a hydrothermal method and fabricated line-patterned IZO QD layers with polydimethylsiloxane (PDMS) molds. Additional hydrothermal growth was conducted to create ZnO nanocolumns (NCs) on the patterned surfaces. Thus, drop-cast and line-patterned sensors and line-patterned samples with NCs grown for 0.5 h (NC(0.5 h)/Line) and 4 h (NC(4 h)/Line) were prepared. Among these four different sensors, the NC(0.5 h)/Line sensor exhibited an excellent response of 26,000 with fast response times of less than 1 s to 10 ppm of acetone. In addition, the detection limit was approximately 0.1 ppm of acetone, and the resistance was almost constant even after repeatability tests. According to UV-vis and X-ray photoelectron spectroscopic analyses, the extraordinary sensing characteristics of NC(0.5 h)/Line were mainly because this sensor had the largest optical band energy and the highest ratio of oxygen vacancies among the tested sensors. On the other hand, the NC(4 h)/Line sensor showed the lowest response of the four sensors. During the long-term growth of NCs, -OH groups are produced on the surface of the material, and Zn(OH)(2) NCs are formed instead of ZnO NCs, resulting in a large decrease in the carrier concentration and active sites. In conclusion, we developed highly sensitive acetone sensors by constructing special morphologies.

Automated summary

Through experiments and analysis, researchers have successfully developed highly sensitive acetone sensors. Among the four different sensors, the NC(0.5 h)/Line sensor exhibited the best response capability, with a low detection limit as well.