Holey Graphene Metal Nanoparticle Composites via Crystalline Polymer Templated Etching

While graphene has sparked enormous research interest since its isolation in 2004, there has also been an interest in developing graphene composite materials that leverage graphene's extraordinary physical properties toward new technologies. Oxidative analogues such as graphene oxide and reduced graphene oxide retain many of the same properties of graphene. While these materials contain many functional moieties, defect formation through current oxidation methods is random which, despite reductive treatments, can never fully recover the properties of the starting material. In the interest of bridging the divide between these two sets of materials for composite materials, here we show a methodology utilizing 2-D covalent organic frameworks as templates for hole formation in graphene through plasma etching. The holes formed act as edge-only chemical handles while retaining a contiguous sp² structure. Holey graphene structures generated act as autoreduction sites for small noble metal nanoparticles which return many of graphene's original electrical properties that can be used for functional composites. Composite materials here show 10³ enhancement of the Raman signal of the underlying holey graphene as well as excellent calculated limits of detection in gas sensing of H₂S (3 ppb) and H₂ (10 ppm).