Modeling of H2O, H2O2, and H2O3 formation mechanisms on graphene oxide (GO) surfaces

Abstract

The role of O2 gas on graphene oxide (GO) surfaces is an area of great interest for heterogeneous catalytic materials in ambient and interstellar conditions. As a result, we investigated the transfer mechanisms of surface hydrogens from OH groups on the basal plane of GO using density functional theory. The reaction mechanisms were calculated in both triplet and singlet states due to the ground state spin states of O2 and the products. By passing O2 gas over GO, we found H2O, H2O2, and H2O3 (singlet state) were generated products. In reference to triplet O2, we found that H2O was produced exothermically, with differences in energy of −0.423 eV and −0.048 eV in the triplet and singlet states, respectively. The triplet state is favored in H2O formation since the O2 acted as a hydrogen shuttle and transported an H-atom from one OH group to the other. H2O2 and H2O3 formation occurred endothermically, requiring 1.08 eV and 0.978 eV in the singlet state, respectively. Additionally, H2O2 in the triplet state resulted in a net energy difference of 2.22 eV. Based on these calculations, GO is a highly unfavorable catalyst for H2O2 formation on the basal plane and is thermodynamically inclined to form H2O.