One step electrochemical exfoliation of natural graphite flakes into graphene oxide for polybenzimidazole composite membranes giving enhanced performance in high temperature fuel cells

In this work, a 3D-printed reactor was designed to enable natural graphite flakes to be used for electrochemical exfoliation to quickly obtain graphene oxide. Graphite foil as a typical raw material of electrochemical exfoliation was also exfoliated for comparison. Under the same conditions (10 V, 1 mol L-1 ammonium sulphate solution as electrolyte), the graphene products obtained by one-step electrochemical exfoliation using natural graphite flakes based on the reactor, have a significantly higher degree of oxidation than products obtained using graphite foil (the oxygen content is increased by 50.2%). In addition, the degree of oxidation can be further increased by increasing the electrolyte concentration or reaction time. This design achieves one-step exfoliation using natural graphite flakes to obtain graphene oxide with tunable oxygen content in short time without using any strong oxidants or strong acids. The as-prepared electrochemically exfoliated graphene oxide (EGO) was used to prepare polybenzimidazole (PBI)/graphene oxide (GO) composite membranes for high-temperature polymer electrolyte membrane fuel cells (HTPEMFC). The 0.5%, 1% and 2% EGO loadings in the PBI membrane increased the peak power density by 13.8%, 24.4% and 29.2%, respectively.

Automated summary

A 3D-printed reactor was designed for electrochemical exfoliation of natural graphite flakes to obtain high degree of oxidation graphene oxide. By adjusting the electrolyte concentration and reaction time, the degree of oxidation can be further increased. The electrochemically exfoliated graphene oxide was successfully used to prepare composite membranes for high-temperature polymer electrolyte membrane fuel cells, resulting in significant improvement in peak power density.