Graphene is a single layered arrangement of carbons that are connected in hexagonal rings to form a sheet. Due to the unique structure, graphene is a flexible and durable material that could be used in many applications. Altering the size and shape of conjugated ring systems are known to affect the pKa of acidic functional groups. This work will show that the acidity of OH functional groups are modified in physical hole defects in graphene. We will focus on small physical hole defects in graphene for the reduction for O2 to H2O2 and show the reaction barriers compared to the industrial catalyst anthrahydraquinone. Density functional theory (DFT) will be used to optimize reaction intermediates in singlet and triplet spin states using the hybrid functional, LC-wPBE. A nudged elastic band (NEB) algorithm is used to calculate the energies of trial images along the minimum energy pathway to find transition states. We will discuss how the NEB calculations reveal the barriers along the H2O2 synthesis pathway in the singlet and triplet states over different modified graphene sheet. Furthermore, the results from the NEB calculations of the transition states will demonstrate how physical hole defects alter the acidity of OH groups attached on the graphene surface.

Hydrogen peroxide synthesis and the influence of graphene acidity of OH groups from physical hole defects

ACS Spring 2022

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