Growth, Characterization, and Application of Vertically Aligned Carbon Nanotubes Using the RF-Magnetron Sputtering Method

The aim of this work is to synthesize and characterizea nanostructuredmaterial with improved parameters suitable as a chemiresistive gassensor sensitive to propylene glycol vapor (PGV). Thus, we demonstratea simple and cost-effective technology to grow vertically alignedcarbon nanotubes (CNTs) and fabricate a PGV sensor based on Fe2O3:ZnO/CNT material using the radio frequency magnetronsputtering method. The presence of vertically aligned carbon nanotubeson the Si(100) substrate was confirmed by scanning electron microscopyand Fourier transform infrared (FTIR), Raman, and energy-dispersiveX-ray spectroscopies. The uniform distribution of elements in bothCNTs and Fe2O3:ZnO materials was revealed bye-mapped images. The hexagonal shape of the ZnO material in the Fe2O3:ZnO structure and the interplanar spacing inthe crystals were clearly visible by transmission electron microscopyimages. The gas-sensing behavior of the Fe2O3:ZnO/CNT sensor toward PGV was investigated in the temperature rangeof 25-300 degrees C with and without ultraviolet (UV) irradiation.The sensor showed clear and repeatable response/recovery characteristicsin the PGV range of 1.5-140 ppm, sufficient linearity of response/concentrationdependence, and high selectivity both at 200 and 250 degrees C withoutUV radiation. This is a basis for concluding that the synthesizedFe(2)O(3):ZnO/CNT structure is the best candidatefor use in PGV sensors, which will allow its further successful applicationin real-life sensor systems.