Catalase-like properties of multilayer graphene oxides and their modified forms

The catalytic system, that mimets catalase enzyme such as “multilayer graphene oxide /peroxide molecule” in aqueous media was investigated. The main factors that influence on catalyst’s effectiveness were determining. The catalytic activity of as-synthesized multilayered graphene oxides, and their modified forms (oxidized and nitrogen doped) were investigated in the decomposition of hydrogen peroxides at room temperature and physiological pHs by measuring the volume of released gases. A phosphate buffer with a pH of 5 to 8 was chosen as the reaction medium. The original and modified samples were characterized using XPS, TPD-MS, Boehm titration analyses. The effect of surface chemistry on the catalytic reaction proceeding has been studied. It was found that catalysis on the graphene plane is determined by the presence of heteroatoms in their structure. The catalytic process takes place in the kinetic zone over the entire accessible surface of the samples. The active sites of the catalysts contain a large amount of both nitrogen and oxygen-containing functional groups. In addition, the surface of graphene oxide is hydrophilic, which enhances the catalytic reaction in an aqueous medium. It has been established that the rate of hydrogen peroxide decomposition by reduced graphene oxide samples is lower than for samples modified with oxygen and nitrogen. The catalase-like activity of graphene increases in alkaline pH up to 7.8. Studies have shown that samples of multilayer graphenes with a high content of functional groups can be an alternative to the catalase enzyme as a catalyst for the decomposition of hydrogen peroxide in physiological solutions.