Author
Abstract
Environmentally benign production processes are required in order to ensure a sustainable graphene supply. Life cycle assessment (LCA) is an established method for assessing life cycle environmental impacts of products and production processes. In this paper, life cycle impacts of five production processes for graphene are reviewed: Chemical reduction of graphite oxide, ultrasonication exfoliation, thermal exfoliation, chemical vapour deposition, and epitaxial growth. The reduction step, including the production of the reduction agent hydrazine, was the main contributor for most impacts in the chemical reduction of graphite oxide. Production of the solvent diethyl ether was the step that contributed the most for ultrasonication exfoliation, so solvent recovery is advised. For thermal exfoliation, microwave heating was the step that contributed the most to environmental impacts of graphene nanoplatelets. For chemical vapour deposition, the methane feedstock production step contributed the most, but methane recovery could reduce the energy use considerably. The environmental impacts of epitaxial graphene were dominated by electricity use for production of the silicon wafer substrate, which means that a ‘greener’ electricity mix can reduce impacts considerably. Overall, it is shown that graphene need not be an energy-intensive material compared to conventional materials used in society today.
Keywords
)