Effect of electrolytic conditions on the structure of exfoliated products of graphite using sulfuric acid and their ability as hydrogen production electrocatalyst supports

Anodic electrochemical exfoliation of graphite in a simple two-electrode configuration using inexpensive and industrially available sulfuric acid is an excellent process for the mass production of graphene oxide. In this study, the effects of the structure of the graphite sheet, voltage and current, and electrolyte concentration on the structure of the exfoliated products and their potential use as a catalyst support were investigated. The results showed that graphite structure is a factor affecting the uniformity of the electrolytic reaction, that voltage/ current is an important factor that can determine whether expansion or exfoliation of the graphite anode is preferentially caused, and that electrolyte concentration is an important factor determining the atomistic structure of the exfoliated products. In addition, they showed excellent ability as catalyst supports for a molecular metal complex showing heterogeneous electrocatalytic hydrogen production. Of note is that the catalytic currents are dependent on the structure such as size, defects, and oxidation degree of exfoliated products.