Synthesis Of Novel Graphene-based Targeted Hydrogen Getter Nanocomposites And Their Properties

The best insulating effect may be seen in the high vacuum multi-layer insulation structure that is typically employed in cryogenic vessels when the vacuum degree of the annular space is better than 1.33×10^-2 Pa.The vacuum degree of the annular space of cryogenic vessels is gradually degraded by outgassing of insulation materials and support structure,as well as tank leakage,reducing the life of cryogenic vessels.The principal gas component that causes vacuum failure of cryogenic vessels’annular space is H₂.Pd O is frequently included in the annular space as a specific hydrogen getter to weaken the heat conduction of MLI annular space gas.Yet,in view of the scarcity of palladium in nature and the critical technological need for cryogenic vessels to maintain temperature,it is significant to develop a new type of efficient and economical hydrogen getter.In this paper,graphene oxide with huge specific surface area and easy loading of metal oxides and organic groups was determined as the composite substrate by molecular simulation.Palladium oxide nanoparticles and alkynyl polyvinyl alcohol（Alkyne-PVA）were loaded on the surface of graphene oxide sheet through experiments,and the hydrogen sorption performance of the Alkyne-PVA-（GO-Pd O）nanocomposite was tested by the"Getter Sorption Properties Test System".（1）Molecular modeling was used to investigate the sorption features and microscopic sorption process of hydrogen on graphene surfaces.The sorption state and location of hydrogen molecules on graphene modified with various oxygen-containing functional groups was observed.The effect of oxygen-containing functional groups on hydrogen sorption was investigated.When the impact of oxygen-containing functional groups on the manufacture of nanocomposites is considered,graphene oxide with a large specific surface area and the ability to load metal oxides and organic groups is chosen as the nanocomposite substrate.（2）Graphene oxide was prepared by chemical oxidation,palladium oxide nanoparticles were loaded on graphene oxide sheets in situ by hydrothermal method.Alkyne-PVA was prepared by propargylamine carbamate method,and Alkyne-PVA-（GO-Pd O）nanocomposites were synthesized by self-assembly method.The structure,composition and morphology of intermediate products and target products were characterized and analyzed by Raman,XRD,XPS,1H-NMR,SEM,EDX and TEM.The integration of graphene oxide,Pd O nanoparticles and alkynyl polyvinyl alcohol was successfully realized,and the nanocomposite showed their special structures.（3）The"Getter Sorption Properties Test System"was set up,and the hydrogen absorption properties of graphene oxide,GO-Pd O,Alkyne-PVA,Alkyne-PVA-（GO-Pd O）nanocomposites and Pd O were tested by static expansion method.The hydrogen sorption isotherms of the prepared materials at room temperature and low pressure were obtained,and the hydrogen sorption characteristics of Alkyne-PVA-（GO-Pd O）nanocomposites were explored.In the preparation of the nanocomposites,the input mass of Pd O only accounts for 4.47%of the total mass of nanocomposites When the equilibrium pressure is 463.8 Pa,its hydrogen sorption capacity reaches 11152.73 Pa L/g.Alkyne-PVA-（GO-Pd O）nanocomposite makes full use of the excellent characteristics of graphene oxide substrate,such as large specific surface area,easy loading of metal oxides and organic groups.Graphene oxide was grafted with noble metal oxides and alkynylated polyvinyl alcohol branches,showing strong sorption capacity for hydrogen at room temperature and low pressure.On the one hand,Pd O has good hydrogen sorption performance,which realizes the initiation of hydrogen sorption;On the other hand,Pd,the product of the initiation reaction,can also be used as a catalyst for hydrogenation of alkynyl unsaturated branches.A small amount of palladium element investment has been rewarded with a huge amount of hydrogen sorption.Alkyne-PVA-（GO-Pd O）nanocomposite has exerted the utilization of palladium element to the extreme and has a good application prospect.