Predicting the Mechanisms for H₂O₂ Activation and Phenol Oxidation Catalyzed by Modified Graphene-Based Systems Using Density Functional Theory

The heterogeneous Fenton-like reaction on metal-free graphene-based catalysts attracts great attention. However, a systematic and comprehensive understanding of the mechanisms for H2O2 activation and pollutant oxidation is still lacking. In this study, the heterogeneous Fenton-like mechanisms on doped and oxygen-containing graphene are investigated using density functional theory. The H2O2 tends to form a surface oxygen and a water molecule on the doped graphene. For the oxygen-containing graphene-based systems, relative to the groups in the basal plane, the separated groups on the edge including hydroxyl, carbonyl, and carboxyl readily activate H2O2 to hydroxyls. However, when the groups are close to each other, more additional side reactions might occur upon H2O2 adsorption, which may inhibit catalyst retrieval. Phenol is selected as a model pollutant to study its oxidation reaction with the adsorbed oxygen formed from the dissociated H2O2. The thermodynamics of the reactions depends significantly on the co-adsorption strengths over different catalysts. Our work provides key fundamental insights into the catalytic performance of various modified graphene-based systems, which could guide the future design and applications of heterogeneous Fenton reactions.