Eco-friendly synthesis of graphene nanoplatelets
Owing to its outstanding electrical, mechanical, and thermal properties; as well as to its unique one-atom-thick two-dimensional carbon structure, graphene has attracted tremendous interest from both academia and industry. Although various synthesis protocols exist for graphene (i.e., top-down and bottom-up approaches), the development of eco-friendly green synthesis processes that are simple and scalable is currently still of great importance. Due to the significant detrimental effects on the environment caused by the toxic chemicals and complicated manufacturing procedures often employed in the synthesis of graphene, its practical applications are very limited, as we have experienced with carbon nanotubes (CNTs). In this context, a wide range of facile and green synthesis strategies have been extensively investigated. Examples of such methods include the efficient reduction of graphene oxide using non-poisonous reducing agents and/or procedures, and the direct exfoliation of graphene from pristine graphite using eco-friendly processes under mild conditions. In this review, we summarize the general aspects and recent progress that have contributed to the development of eco-friendly green synthesis procedures for graphene, including mechanisms, properties, and applications. In addition, challenges and perspectives on the future of this field are also discussed.