Study On Preparation, Characteri-Zation And Property Of Composites Of Intercalated Graphite Oxide

Graphite oxide (GO) has a two dimensional layered structure with larger space distance than graphite. Some oxygen-containing organic groups on the GO sheets exhibt many especial properties, such as ion exchange capacity, excellent hydrophilic and oleophilic properties. These features provide the theoretical basis in preparing functional menbrane materials and intercalated GO compounds. A series of composites of intercalated graphite oxide with excellent optical, electrical, magnetic and catalytic properties have been successfully synthesized.Because of the existence of the oxygen-containing organic groups and the large spacing of graphite oxide, the new composites of metal ions intercalated graphite oxide (M2+/GO) were successfully prepared by the coordination reaction which obtained the highly dispersed metal on GO sheets. Based on the obstruction effect of GO sheets, MS/GO with uniform size, good dispersion and high catalytic activity was prepared by mixing M2+/GO with sulfur source.(1) Preparation and characterization of new M2+/GO composites. Researchs show that the effects of pH, temperature, time and the adding content of metal ions on the loading of metal ions is very distinct. The results of volumetric analysis show that:at pH=11～12, T=30℃, t=24h, the loadings of Cu2+and Zn2+can reach to 0.18gCu/gGO and 0.17gZn/gGO by mixing 0.5g GO and 0.005mol M2+. The results of XRD show that the composites of Cu2+/GO and Zn2+/GO all have layered structure. The space distances of Cu2+/GO and Zn2+/GO are 0.694nm and 0.734nm, respectively. The decreased spacing, migrating of IR peeks of C=O, C-O and changing of binding energy of O1s, Cu2p3/2 and Zn2p3/2 reveal that the chemically combination has occurred between metal ions and GO. Moreover, impurities of metal oxide are found in the composites.(2) Preparation, charactrerization and catalytic performance of MS/GO composites. MS/GO were synthesized in the reaction of M2+/GO and thiacetamide by using water solvent and sodium dodecyl benzene sulfonate dispersant. The results show that CuS/GO and ZnS/GO composites all have lamellar structure. The sulfides particles with hexagonal system are highly dispersed on the sheets of GO. The shapes of CuS and ZnS are grained and plate-like structure, respectively.The catalytic activities of the composites were investigated in the oxidation of methylene blue by hydrogen peroxide. The results reveal that, in the mixed solution of 50ml,30mg/L methylene blue and 10ml H2O2 (30%), the decolorization rates of methylene blue are 10.2%(100min, no catalyst added),95.2%(100min, Cu2-/GO composite as catalyst), 92.81%(3min) and 99.3%(3h) when using MS/GO composites as catalyst, 76%(3h, CuS as catalyst). The results show that graphite oxide can improve the catalytic activity of metal sulfides in the degradation of methylene blue by the oxidation of hydrogen peroxide. The catalytic activities of CuS/GO and ZnS/GO were also studied in the oxidation of fuchsin by hydrogen peroxide and showed good results (the decolorization rate reached to 97% after 3h).(3) Characterization of M2+/GO prepared in the mixed organic solvent. To prepare pure composites of Cu2+/GO and Zn2+/GO, the mixed solvent of ethanol and formamide was carried out, which exhibited a good result. No metal oxide impurities can be observed in Cu2+/GO and Zn2+/GO composites when the mixed solvent of ethanol and formamide (V/V=4:3) is used. CUSO4 and Zn(NO3)2 were disolved in above mixed solvent respectively. GO was disolved in the same solvent by ultrasonic dispersion for 20min. After that, the metal salt solution and GO solution were mixed and reacted for 24h, the two composites:Cu2+/GO and Zn2+/GO were obtained. The products were characterized by XRD, SEM, IR, EDS and XPS. The results show that more obvious and regular lamellar structure can be found in these composites than that of the composites prepared in water solvent. More important, no metal oxide impurites can be found on the composites prepared by mixed solvent. The migrating of IR peaks of C=O, C-O and the appearing of the IR peaks of Cu-O, Zn-O indicate that the coordination bond between metal ions and GO occurs. From the spectrums of XPS, it can be found that:(ⅰ) the binding energy values of O1s (C=O) on Cu2+/GO and Zn2+/GO reduced by 0.47eV and 0.43eV compared to GO, respectively; (ⅱ) the binding energy of O1s (C-O) on Cu2+/GO and Zn2+/GO increased by 0.22eV and 0.21eV compared to GO; (ⅲ) the binding energy of Cu(Ⅱ)2p3/2 and Zn(Ⅱ)2p3/2 reduced by 0.47eV and 0.66eV compared to CuSO4·5H2O and Zn(NO3)2·7H2O. The results show that the copper and zinc atoms accept electrons from oxygen atoms; the oxygen atoms give electrons to metal ions to form coordination bond.