Redefining Graphene Oxide: The Role of Organosulfate Groups in Charging Dynamics and Colloidal Stability

Understanding the charging dynamics of graphene oxide (GO) is essential for optimizing its properties and designing more efficient devices across all applications. Despite its significance, the forces defining the chemistry of GO have remained elusive. Notably, the presence of unusually high proton concentrations in GO dispersions and the absence of a point of zero charge cannot be explained by existing models. The findings reveal that organosulfate groups, rather than multifunctional oxide groups, govern the charging behavior of GO. Detailed elemental analysis and modeling results highlight the predominant role of these groups throughout the GO life cycle—during synthesis, storage, and processing stages. This understanding offers a platform for tailoring the electrical double layer around atomically thin polyelectrolyte membranes to fine tune their properties, while providing crucial guidelines for achieving consistent results and adjusting the properties of as‐synthesized GO by modifying its charging behavior.