피롤 말단기를 가진 알칸싸이올 금 나노입자 필름의 기체 센서의 특성 연구

Abstract

Few centuries ago, gold nanoparticles were already applied to not only paint materials due to their beautiful luster, but also nowadays organic photovoltaics, sensor probes, drug delivery and electronic conductor as cutting edge technology thanks to distinctive optical property and high electrical conductivity. Besides, gold has been known for the most stable atom and having the highest resistance against oxidation among atoms of 8th column in the periodic table. In the late 1970s, since it was found out that gold nanoparticles could be activated to various reactions if highly dispersed, these days it has been dealt with in many areas. Especially, it can be used as chemical sensors because gold nanoparticles have high sensitivity, selectivity and fast reversibility. These sensors’ system principle is fundamentally based on the measurement of electrical resistance which is changed if exposed to organic vapors. These changes correlate with intrinsic dielectric constant and distance between gold cores. In this study, we reviewed the latest research and studied sensing properties to organic vapors through quantitative and qualitative analysis. Firstly, four kinds of gold nanoparticles having different ligands were synthesized respectively and vapor sensing properties of their coated films on IDA electrode have been investigated. The IDA electrodes with 20 μm pattern are fabricated by conventional photo lithography method. Diameters of the gold cores were observed in the 2.5 - 3.5 nm range by Transmission electron microscopy and measurement of the sulfur, nitrogen and gold peak areas of the films were appeared by X-ray photoelectron spectroscopy. Pyrrole terminated alkanelthiol protected-gold nanoparticle (PyAuNP) films exhibit an anomalous response in which the resistance increases for polar organic vapors like methanol, ethanol, propanol and dimethylformamide (DMF). The magnitude of the resistance change correlates well with dielectric constant and distance change between the gold cores. This result is accounted to a pyrrole-stacking structure generating separation of the gold cores in which the resistance exceptionally increases for polar organic vapors. This is because polar organic vapors can be adsorbed on surface of pyrrole-terminated gold nanoparticles which have higher polarity relatively than methyl-terminated gold nanoparticles.