Template Free Synthesis of Hollow Ball-Like Nano-Fe(2)O(3) and Its Application to the Detection of Dimethyl Methylphosphonate at Room Temperature

This paper is focused on the template-free synthesis of nanosized ferric oxide (nano-Fe(2)O(3)) and its application in quartz crystal microbalance (QCM) resonators to detect dimethyl methylphosphonate (DMMP), a simulant of Sarin. The X-ray diffraction (XRD) patterns confirm that the synthesized samples are made of Fe(2)O(3) and the scanning electron microscopy (SEM) pictures show that the samples have ball-like shapes. The DMMP sensors with a sensing film of hollow ball-like and solid ball-like Fe(2)O(3) are fabricated and their sensing characteristics are compared. The sensitivity of the hollow ball-like Fe(2)O(3) sensor is more than 500% higher than the one of the solid ball-like Fe(2)O(3) sensor. The hollow ball-like nano-Fe(2)O(3) can be synthesized by a novel low temperature hydrothermal method. The sensors with the hollow ball-like Fe(2)O(3) film perform well in a range of 1 to 6 ppm, with a sensitivity of 29 Hz/ppm at room temperature, while the appropriate recoverability and selectivity are maintained. In addition, the performance of different thicknesses of the sensing film of the hollow ball-like nano-Fe(2)O(3) is investigated and the optimized relative film thickness of the hollow ball-like nano-Fe(2)O(3) is found to be 20 μg/mm(2).