In situ formation of suspended graphene windows for lab-based XPS in liquid and gas environments
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. The challenge, however, is in ensuring reliable production of graphene windows that are sufficiently leak-tight for extended measurements.
In the paper 'In situ formation of suspended graphene windows for lab-based XPS in liquid and gas environments', as published in The European Society Journal for Catalysis, a team of researchers headed by this department and including the Catalysis Hub at Harwell, Diamond Light Source, UCL and the University of Manchester demonstrate a PDMS/Au(100 nm) supported transfer method which reliably produces suspended graphene on perforated silicon nitride membranes without significant contamination.
A yield of ~95% was achieved, based on a single-layer graphene covering >98% of the holes in the silicon nitride membrane. Even higher coverages were achieved for stacked bilayer graphene, which allowed for wet etching (aqueous KI/I2) of the Au support to be observed in a conventional lab-based XPS system, and thereby this demonstrates the in situ formation of leak-tight, suspended graphene windows, which allow gas-phase measurements at close to atmospheric pressure. This is promising for future XPS under higher-pressure gas environments in conventional lab-based systems.
