Synthesis of Three-dimensional Graphene and Optimization of Its Morphology

Zahra Khosroshahi, Fathallah Karimzadeh, Mahshid Kharaziha

Due to electrical properties (high electron mobility) and electrochemical characteristics (high electron transport rate), graphene-based  materials have been widely applied for various scientific fields. However, due to their two-dimensional  structures, these materials have low active sites for reaction. Therefore, changing from two-dimensional sheets dimensional to the three-dimensional ones  could provide graphene-based materials with high specific surface and electron and mass transport particles. For these purpose, reduced graphene oxide (rGO) and polystyren (PS) aqueous solution were mixed with two different  weight ratios kinetic. In this study, the three-dimensional graphene (3DG) was synthesized with graphene oxide using sacrificial PS particles. For this purpose, rGO and the PS aqueous solution were mixed with two different weight ratios of 95:5 and 85:15. Then, the 3DG-PS scaffolds were synthesized by controlling the pH value in the range of 6-8. Subsequently, PS particles were removed by immersing the synthesized scaffolds in toluene. In this research, the effect of filtering through the member filter and centrifuge on the morphology of the  scaffolds was  investigated. The scaffolds were characterized with X-ray diffraction and scanning electron microscopy. The results showed the formation of 3DG with a uniform distribution of porosities by  using the  centrifuge procedure. Moreover, the sacrificial PS particles were completely removed when the rGO to PS weight ratio was 95:5. So, 3DG with the uniform distribution of microscopy porosity could be synthesized through the sacrificial mold method and the centrifuge procedure; graphene oxide was also reduced with the PS weight ratio of 95:5. Further, based on the electrochemical evaluation of  this optimized sample, as compared to the  rGO , it was found that the 3DG had better electrochemical properties than the rGO. Therefore, 3DG with  the optimized rGO to PS weight ratio of 95:5 could be an ideal substitute for rGO in electrochemical applications.