I assume you are working with powder samples of graphene and GO, if you are using flakes, pellets, or crystals you can generally mount the samples with clips or carbon tape.

Generally you can mount powder samples well on carbon tape, you need to make sure that the the tape is well covered and excess powder is blown off being being put into the system. To mount the powder just scoop a small amount onto the tape and press the powder into the tape with a scapula. If coverage is significant you will not see signal from the carbon tape underneath.

You can also use indium foil to mount powders. First clean the foil with solvents or scratching, then placing some powder onto it and fold the indium in half pressing down on the powder pocket. The powder will imbed into the soft metal. Blow off excess powder and mount the foil with clips or carbon tape. Indium is a convenient choice since the peak position of indium is far from carbon, but this method tends to produce low coverage so you will get some signal from the substrate. The low coverage introduces a problem since you may not know how clean(no carbon) the foil is.

Thank you very much for your detailed answer. It will surely help!

I agree carbon tape generally works well for this purpose. I have had issues with outgassing from powdered graphene/GO samples so would recommend storing them under vacuum if possible.

Store the graphene/GO samples prior to loading them into the XPS chamber and carry out the characterisation?

Thank you for your help!