Synthesis, characterization and life cycle assessment of electrochemically exfoliated KOH-activated holey graphene

Highlights

● Electrochemically exfoliated graphene (EEG) was prepared from pencil graphite rods.

● Holey graphene (HG) was prepared from EEG via the KOH activation process.

● SSA was increased with the increase of KOH amount, because of pore generation.

● In EEG production, electricity and H₂SO₄ have the highest environmental impact.

● In HG production, KOH and graphene have the highest environmental impact.

Abstract

Graphene materials have drawn tremendous attention in recent years. The formation of holes and pores on graphene sheets can provide transfer channels and facilitate the ion/electron transport kinetics. In this study, graphene nanosheets were prepared electrochemically, and then, they were used as the starting material for the preparation of holey graphene (HG) through the KOH activation process. The weight ratio of initial electrochemically exfoliated graphene (EEG) to KOH was optimized according to the morphological features, BET surface area examination, graphene number of layers calculated from XRD patterns, and the I_D/I_G ratio obtained from Raman analysis. Results showed that increasing the KOH amount led to the achievement of higher values of I_D/I_G and surface area and less re-stacking of graphene sheets which occurs because of the heat treatment process. The environmental burdens of the production routes for the preparation of EEG and HG were investigated by cradle-to-gate life cycle assessment (LCA). The LCA results of EEG production indicated that electricity with the contributions of 94%, 91%, 82%, and 75% of the total impact in four environmental categories, including fossil fuel depletion, ozone depletion, global warming, and smog was the main environmental weakness. In the pore generation process, KOH was recognized as the biggest contributor (about 51% to 83% of the total impact) in six impact categories, including ozone depletion, non-carcinogenics, smog, global warming, carcinogenics, and eutrophication which could be attributed to its high consumption amount (21.9 kg). This work offers environmental considerations for the development of sustainable graphene materials.

Graphical abstract

Keywords

Holey graphene / Electrochemical exfoliation / Life cycle assessment (LCA) / Environmental impact / KOH activation

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Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s11783-023-1755-4 and is accessible for authorized users.

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