 Graphene has been receiving increasing attention from both academia and industry due to its unique properties. However, the material's high cost and limited availability have hindered its commercialization. X-ray photoelectron spectroscopy, XPS, is a popular technique used to determine the elemental and chemical composition of materials. This study examined the effect of graphene particle morphology on XPS results, varying the information depth from 10 nanometers to 30 nanometers. Two types of graphene nanoplatelets were tested, one with lateral dimensions of approximately 100 nanometers and another with dimensions in the micrometer range. Both types of particles were functionalized with either oxygen or fluorine. The results showed that the larger particles had a greater tendency to be more heavily functionalized than smaller particles. Additionally, only XPS combined with hard X-ray photoelectron spectroscopy, HACSPS, was able to detect the functionalization at the outermost surface of the particles or even of the stacks, providing new insight into the functionalization process. This article was authored by Giovanni Ciamello, Xenia Nigg, Dmitri Sioniai, and others. We are article.tv, links in the description below.