In Situ Formation of Suspended Graphene Windows for Lab‐Based XPS in Liquid and Gas Environments

• Published in: ChemCatChem Vol. 16; no. 16
• Main Authors: Jones, Elizabeth S., Drivas, Charalampos, Gibson, Joshua S., Swallow, Jack E. N., Jones, Leanne A. H., Bricknell, Thomas D. J., Spronsen, Matthijs A., Held, Georg, Isaacs, Mark A., Parlett, Christopher M. A., Weatherup, Robert S.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 26-08-2024
• Subjects: Ambient Pressure; Bilayers; Graphene; In situ; Membranes; Phase measurement; Photoelectrons; Silicon nitride; Transfer; X-ray Photoelectron Spectroscopy
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.202400239

Environmental cells sealed with photoelectron‐transparent graphene windows are promising for extending X‐ray photoelectron spectroscopy (XPS) to liquid and high‐pressure gas environments for in situ and operando studies. However, the reliable production of graphene windows that are sufficiently leak‐tight for extended measurements remains a challenge. Here we demonstrate a PDMS/Au(100 nm)‐supported transfer method that reliably produces suspended graphene on perforated silicon nitride membranes without significant contamination. A yield of ~95 % is achieved based on single‐layer graphene covering >98 % of the holes in the silicon nitride membrane. Even higher coverages are achieved for stacked bilayer graphene, allowing wet etching (aqueous KI/I2) of the Au support to be observed in a conventional lab‐based XPS system, thereby demonstrating the in situ formation of leak‐tight, suspended graphene windows. Furthermore, these windows allow gas‐phase measurements at close to atmospheric pressure, showing future promise for XPS under higher‐pressure gas environments in conventional lab‐based systems.
In situ X‐ray photoelectron spectroscopy (XPS) of a reaction at the solid‐liquid interface is performed in a lab‐based system under ultra‐high vacuum conditions (UHV). To enable this, a PDMS/Au‐supported transfer process is demonstrated that reliably produces continuous, high‐quality and contamination‐free suspended graphene windows which successfully seal liquids and high pressure (~1 bar) gases.