Research On Optical Fiber Sensing Of Metal Organic Frameworks Coated Based On Graphene Oxide

Graphene oxide(GO)has a good dispersion in water and ethanol solution,which due to the introduction of a large number of oxygen-containing groups,such as-OH,-COOH,C=O.Moreover,the specific surface area of GO itself is relatively large,which provides a strong guarantee for the more abundant porous structure of the synthesized metal organic framework(MOF).A MOF coated optical fiber sensor based on GO synthesis has been studied in this paper and the main research contents are shown as follows:1.Some typical optical fiber sensing structures,the sensing principles and GO optical fiber coating technology were introduced.The development and synthesis methods of MOF and the synthesis conditions are also briefly described.2.An electrochemical(EC)method for the synthesis of metal organic framework(MOF)was proposed.This synthetic method can efficiently utilize organic substrates,improve energy efficiency,and synthesize reactions at room temperature.It was found that the MOF synthesized with GO as organic substrate had the characteristics of high resistance,poor hydrophilicity and enhanced adhesion to glass substrate.FTIR spectroscopy showed that the carboxyl group in GO was bound with nickel metal to form a very stable covalent bond.3.A capillary heating coating method was proposed to deposit GO on the side surface of optical fibers.This method enables GO to distribute evenly on the surface of the optical fiber and conduct electricity,which provides a strong guarantee for uniform GO-Ni MOF coating.The thickness of the synthesized optical fiber MOF coating is 3~4 ?m.4.A study on the thermal stability of GO-Ni MOF in air based on optical fiber sensing technology is presented.Based on the sensing principle of optical fiber MachZehnder interferometer(MZI),when the refractive index of the effective medium coated on the surface of the optical fiber changes,the interference spectrum in the spectrum will drift.After heating and cooling experiments,it is found that the endurance temperature of the MOF in the air is 125 °C.When the temperature exceeds that,the chemical bond of the MOF will break.5.A study of hydrogen adsorption properties of GO-Ni MOF based on optical fiber sensing technology.Based on the sensing principle of MZI,the cladding mode of the optical fiber changes due to the medium refractive index of the refractive surface after the MOF coating adsorbs hydrogen molecules,resulting in severe total reflection conditions,increased total reflection angle and light leakage in the cladding.With the increase of the concentration of hydrogen molecules adsorbed,the total reflection angle increases continuously.The experimental results show that the MOF can adsorb 0.6 wt% hydrogen in 18°C air,and its adsorption characteristic is physical adsorption.