Modulation Of Structure And Performance Of Functional Materials By Using Graphene

In the recent years, the graphene-based composites or composite films and nanomaterials synthesized by using graphene have been research hotspot. The graphene/manganese dioxide (Mn2) composites combine the conductivity of graphene with the catalytic performance of MnO2. The catalytic performance improvement of composites can be realized by adjusting the morphology of MnO2.In this paper, the composites of graphene oxide (GO) nanosheets/γ-MnO2 nanohydrangeas were obtained through taking GO nanosheets as template, KMnO4 and MnS04 as precursors. The diameter of MnO2 nanohydrangeas distributed on the surface and edge of GO nanosheets is about 300-500 nm, consisted of MnO2 nanosheets of 20 nm in thickness. The composites show ultrafast catalytic rate in degrading methylene blue (MB). The fully degradation of MB only needs 150 s. The active catalysis of composites is contributed to synergistic effect of GO and MnO2. During degradation of MB, GO nanosheets not only provide large specific surface area for the adsorption of MB, but also as electron transfer matrix to accelerate oxidation of MB.Ultrathin MnO2 hollow nanoballoons (UMHNBs) have a large ratio of interfacial to total atoms, corresponding to expected novel performance. However, the synthesis is a challenge due to the difficulty in controlling the concentration of the unit cells. Herein, we describe a strategy to synthesize dry intact UMHNBs, through a one-step synthesis by inflating MnO2 (reduced from KMnO4) with CO2 (oxidized from single-layer graphene oxide nanosheets) followed by instantly freeze-drying. UMHNBs are 30-500 nm in diameter with the shell thickness of 3.7 nm, packing with 5 layers of [MnO6] unit cells in the form of δ-MhO2. UMHNBs show so far the highest catalytic activity for decomposing the organic dye methylene blue (MB),15 times of the biggest reported value, and have long-term catalytic efficacy and durability. The described strategy in this paper paves a new way to assemble ultrathin hollow nanoballoons by making use of graphene nanosheets.The graphene/polymer composite films not only enhance the stability of graphene, but also incorporate the conductivity, mechanical property of graphene with the flexibility of polymer. How to realize the uniform distribution of graphene in polymer matrix is main challenge to improve the performance of composite films. We study the dispersion behavior of GO and poly vinyl chloride (PVC), and obtain the stable GO/PVC mixed solution.The uniform distribution of rGO in matrix of PVC was realized, and rGO/PVC composite films with good mechanical strength and flexibility were obtained, where reducing agents (ascorbic acid, NaBH4, N2H4·H2O, HI), reduction sequence and film preparation strategy were varied.In this thesis, GO nanosheets were made good use of in constructing catalysts with big specific surface areas, and improving performance of polymer composites, which expands knowledge of GO and functional materials based on colloid and interface science. It paves new ways for self assembly and applications like catalysis.