Preparation And Properties Of Graphene-supported Irreversible Organic Hydrogen Absorbing Materials

Hydrogen gas has important applications in energy,chemical and other fields.However,the existence of hydrogen will bring some unfavorable impacts in some special environments.Therefore,it is essential to develop the hydrogen elimination and control materials in order to guarantee environmental safety.It is a feasible method to absorb and eliminate the hydrogen or its isotopes by using hydrogen absorbing materials,in which the irreversible hydrogen getters at normal temperatures and pressures are more important.They are usually prepared by mixing the carbon-supported Pd catalyst with the solid-state alkynyl polymer materials.However,such hydrogen getters have problems that there are large difficulties or barriers between the reaction substrate and solid catalyst,the Pd is easy to agglomerate,and materials is difficult to shape,which affects its hydrogen absorption efficiency and application seriously.Graphene is a great carrier of nanocatalyst because of its large surface area,and the Hydorgen overflow effect is great for Hydrogen transferring to react with unsaturated alkynyl organic compound.This research aims to prepare novel hydrogen getters which can eliminate hydrogen at normal temperatures and low pressures,based on the idea of mixing graphene supported palladium or palladium nickel nanocatalysts with an unsaturated alkynyl organic compound,in order to solve the problems of insufficient contact between catalyst or hydrogen and reactant.Graphene-supported palladium nanocatalyst(Pd/rGO)was prepared by one-step reduction method.The chemical composition,crystal structure and particle size distribution of Pd/rGO catalysts were characterized,and the results show that the oxide grapheme is reduced successfully,and Pd nanoparticles with good crystal structure and narrow particle size distribution are uniformly dispersed on the graphene.Then the Pd/rGO catalysts were mixed uniformly with1,4-diphenylethynylbenzene(DEB)and the Pd/rGO-DEB composites were obtained.The results show that Pd nanoparticles were mixed uniformly with alkynyl organic,and the hydrogen uptake capacity increased with the increase of the content of Pd nanocatalyst in the certain contentration,which by the addition reaction of the triple bond in DEB completely with hydrogen to fo rm the carbon-carbon single bond.Based on the research of single Pd nanocatalyst,the one-step reduction method was also used to support the palladium nickel bimetallic nanocatalyst on graphene.The results show that the Pd-Ni bimetallic alloy nanoparticles were also distributed uniformly on the rGO with good crystal structure and narrow particle size distribution.Then the Pd-Ni/rGO catalysts were mixed uniformly with DEB and the Pd-Ni/rGO-DEB composites were obtained.Microscopic tests show that catalyst and reactants mixed uniformly,and the hydrogen absorption tests show that the addition of Ni can improve the hydrogen absorption capacity of Pd-Ni_-/rGO-DEB composites when comparing with Pd/rGO-DEB composites which has same contents of nanocatalyst,and the best is be obtained with the molar ratio of Pd and Ni of 2:2.Using oxide grapheme and carbon nanotubes to prepare the carbon aerogel,and the Pd nanocatalyst was supported on its surface.Then Pd/CA catalysts were mixed uniformly with DEB and the hydrogen uptake composites(Pd/CA-DEB)were prepared.The results show that the metal nanoparticles were dispersed uniformly in the three-dimensional network structure of carbon aerogels and the Pd/CA-DEB composites are with good formability,taila bility and hydrogen uptake properties.The hydrogen uptake capacities of composites with different carbon nanomaterials as supports have been evaluated and the results show that the carbon aerogel,graphene and the micromorphous activated carbon are with t he best hydrogen absorption capacity.