Synthesis of Janus graphene for spatial separation of charges and reduction-oxidation reactions in colloidal photocatalysts

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Photocatalyst particles are attractive for many applications, but electron-hole recombination and surface back-reactions are major problems limiting their efficiency. These problems stem from short separation (~ nanometers) between reduction and oxidation (redox) sites in conventional systems. Here, we show that 2-dimensional Janus particles — Janus graphenes — can be used to spatially separate redox sites by large distances (~ micrometers) on opposite faces of conductive, atomically thin sheets. We used a silicon wafer and a polymer film to successively expose and protect alternate graphene oxide (GO) faces for asymmetric deposition of Pt and TiO2 nanocrystals, thus producing Janus graphene particles (Pt [vertical line] GO [vertical line] TiO2). We used electron microscopy of Janus graphene cross-sections to directly and conclusively show Pt and TiO2 particles on opposite faces of monolayer GO sheets. Spatial separation of redox sites in Pt [vertical line] GO [vertical line] TiO2 — dispersed in liquid — was demonstrated by photoinduced, reductive deposition of Pd onto reduction sites. Although future scale-up of the synthesis is necessary, Janus graphenes could be synthesized with many photocatalytic materials and may provide a general system for spatial separation of redox sites in photocatalyst particles.


Type of resource text
Form electronic; electronic resource; remote
Extent 1 online resource.
Publication date 2017
Issuance monographic
Language English


Associated with Holm, Alexander
Associated with Stanford University, Department of Chemical Engineering.
Primary advisor Cargnello, Matteo
Primary advisor Frank, C. W
Thesis advisor Cargnello, Matteo
Thesis advisor Frank, C. W
Thesis advisor Bent, Stacey
Advisor Bent, Stacey


Genre Theses

Bibliographic information

Statement of responsibility Alexander Holm.
Note Submitted to the Department of Chemical Engineering.
Thesis Thesis (Ph.D.)--Stanford University, 2017.
Location electronic resource

Access conditions

© 2017 by Erik Bjoern Alexander Holm
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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