Abstract: We will present our results that large-area, atomically-thin metal films (Pt, Au, Ir, Pd and Cu) can be grown epitaxially on graphene (GR) using electrodeposition. We will focus particularly on Pt films that are one to several multilayers thick (Pt_ML) epitaxially grown on graphene (Pt_ML/GR).
These Pt_ML/GR 2D systems have covalent bonds at the Pt_ML/GR interface, and this intimacy between the layers serves to make the GR a “chemically transparent” barrier that allows catalytic chemistry to take place above it, while protecting the Pt below it from loss. We will specifically show that graphene does not restrict access of the reactants for the canonical oxygen reduction reaction (ORR) but does block Pt from dissolution or agglomeration. These architectures simultaneously achieve enhanced catalytic activity and unprecedented stability, retaining full activity for ORR beyond 1000 cycles.
Using X-ray photoemission/absorption spectroscopy, high-resolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy and electrochemical methods, we show that Pt/GR hybrid architectures induce a compressive strain on the Pt films, thereby increasing their oxygen as well as carbon dioxide reduction (ORR and Co2RR) activity. Our room-temperature, fully-wetted synthesis approach should allow for efficient charge, strain, phonon and photon transfer between the films and their support, impacting not just the performance of catalysts, but also those of electronic, thermoelectric and optical materials.