▎ 摘　　要

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, Delta E-C1s, can be described with high accuracy by Delta E-C1s = A(c(0) - c(l))(2)+E-0, where c(0) is the oxygen concentration, A = 52.3 eV, c(l) = 0.122, and E-0 = 1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.