Complete hydrolysis of organosulfates yields to complete exfoliation of graphite oxide

Abstract

Graphene oxide (GO) is a highly versatile material with broad applications, but its acidic nature and the presence of sulfur-containing groups poses significant challenges for biomedical and environmental uses. These groups, mainly in the form of organosulfates, contribute to excessive acidity, which affects the stability of GO and complicates large-scale production due to the need for multiple washing steps. This study is focused on developing an efficient method to fully remove organosulfates. By combining basic and organic acid treatments, complete hydrolysis of sulfate groups was achieved, leading to a significant reduction in acidity and, contrary to expectations, facilitating the exfoliation of GO without requiring additional sonication. This might be due to some organosulfates bound to carbons of different graphite layers. The optimized process resulted in monolayer-rich GO with enhanced dispersion stability, making it more suitable for a wider range of applications. These findings offer a scalable and effective approach to improving the chemical purity and structural properties of GO, expanding its potential in advanced technologies.