The ripple's enhancement in graphene sheets by spark plasma sintering

This paper introduces a simple and effective process of directly enhancing the ripple formation of graphene sheets by using spark plasma sintering (SPS) system. The morphology, microstructure and surface property of the pristine and SPS treated graphene sheets were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and contact angle meter. The results reveal that: 1) A large amount of ripples can be induced in graphene sheets after SPS treatment at 1300 °C, and the pristine graphene surfaces change from smoothness into roughness with the patterns; 2) There are three kinds of graphene ripples with different structures after SPS treatment; (3) After the formation of ripples, the SPS-treated graphene sheets become hydrophobicity. In addition, the formation mechanism of the graphene ripples was also discussed in this paper.