An electrochemical route to holey graphene nanosheets for charge storage applications

Holey graphene nanosheets are potentially useful in several relevant technological applications, including electrochemical energy storage and molecular separation. Access to this material is mostly accomplished by resorting to standard graphene oxides obtained by common routes (e.g., the Hummers method). However, such a type of highly oxidized graphenes may not be the best option as a precursor to holey graphene on account of their chemical/structural heterogeneity and harsh synthesis conditions. Here, we report the use of highly oxidized graphene nanosheets derived by an electrochemical exfoli-ation/oxidation strategy as an alternative precursor to holey graphene. Compared to a standard graphene oxide with the same extent of oxidation, the electrochemically derived precursor exhibited larger aro-matic domains, which provided a structural basis for its higher electrical conductivity, as well as smaller and denser oxidized regions, associated to a higher chemical homogeneity and lability of its oxygen-containing functional groups. Through selective chemical etching of the oxidized domains, the latter feature was exploited to afford holey graphene nanosheets having smaller and more uniform holes. When used as an electrode material for electrochemical charge storage, the electrochemically derived holey graphene outperformed its standard graphene oxide-based counterpart in terms of capacity and energy density. Overall, boasting distinct structural and chemical characteristics, highly oxidized gra-phene obtained by electrochemical means can be regarded as a prospective advantageous precursor to many graphene-based materials whose preparation has traditionally relied on the processing of gra-phene oxides. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).