Pisarkiewicz Tadeusz, Maziarz Wojciech, Małolepszy Artur, Stobiński Leszek, Michoń Dagmara Agnieszka, Szkudlarek Aleksandra, Pisarek Marcin, Kanak Jarosław, Rydosz Artur
Institute of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland.
Faculty of Chemical and Process Engineering, Warsaw University of Technology, Waryńskiego 1, 00-645 Warsaw, Poland.
Sensors (Basel). 2021 Feb 2;21(3):1011. doi: 10.3390/s21031011.
Multilayers consisting of graphene oxide (GO) and α-FeO thin layers were deposited on the ceramic substrates by the spray LbL (layer by layer) coating technique. Graphene oxide was prepared from graphite using the modified Hummers method. Obtained GO flakes reached up to 6 nanometers in thickness and 10 micrometers in lateral size. Iron oxide FeO was obtained by the wet chemical method from FeCl and NHOH solution. Manufactured samples were deposited as 3 LbL (GO and FeO layers deposited sequentially) and 6 LbL structures with GO as a bottom layer. Electrical measurements show the decrease of multilayer resistance after the introduction of the oxidizing NO gas to the ambient air atmosphere. The concentration of NO was changed from 1 ppm to 20 ppm. The samples changed their resistance even at temperatures close to room temperature, however, the sensitivity increased with temperature. FeO is known as an n-type semiconductor, but the rGO/FeO hybrid structure behaved similarly to rGO, which is p-type. Both chemisorbed O and NO act as electron traps decreasing the concentration of electrons and increasing the effective multilayer conductivity. An explanation of the observed variations of multilayer structure resistance also the possibility of heterojunctions formation was taken into account.
通过喷雾层层（LbL）涂层技术，将由氧化石墨烯（GO）和α - FeO薄层组成的多层结构沉积在陶瓷基板上。氧化石墨烯采用改进的Hummers方法由石墨制备而成。所获得的GO薄片厚度可达6纳米，横向尺寸为10微米。氧化铁FeO通过湿化学方法由FeCl和NHOH溶液制得。制备的样品以3层LbL（GO和FeO层依次沉积）和以GO为底层的6层LbL结构进行沉积。电学测量表明，在向环境空气气氛中引入氧化性NO气体后，多层结构的电阻降低。NO的浓度从1 ppm变化到20 ppm。即使在接近室温的温度下，样品的电阻也会发生变化，不过，灵敏度随温度升高而增加。FeO是一种已知的n型半导体，但rGO/FeO混合结构的行为与p型的rGO类似。化学吸附的O和NO都充当电子陷阱，降低电子浓度并提高多层结构的有效电导率。考虑了对观察到的多层结构电阻变化的解释以及异质结形成的可能性。
