Synthesis-in-place hydrothermal growth of hematite nanorods on patterned substrate for highly sensitive and rapid acetone detection

Hematite (alpha-Fe2O3) is an attracting gas sensing material for detecting volatile organic compounds due to its adjustable semiconducting properties and abundant reserves. However, its low sensitivity in thin film structures requires the design of nanostructures for practical applications. Herein, we present a facile hydrothermal method for directly grown hematite nanorods on patterned SiO2/Si substrate. It was demonstrated that hematite nanorods were synthesized directly on the area of Pt interdigitated electrodes on a SiO2/Si substrate using a onestep hydrothermal synthesis process. The optimal synthesis conditions were determined by analyzing the morphology and gas sensing performance of hematite nanorods, which varied with synthesis time. Rapid response time of less than 5 s to acetone at 350 degrees C was achieved with pristine hematite nanorods. To improve the gas sensing properties, hematite nanorods were decorated with Au nanoparticles, dramatically enhanced sensitivity and selectivity to acetone in comparison with the sensing properties of pristine hematite nanorods. Furthermore, the sensors displayed rapid response and long-term stability. Our synthesis-in-place hydrothermal method for hematite nanorods expands the potential use of this strategy to fabricate high-performance gas sensors with various nanostructured metal oxides.