Quantum ESPRESSO package was used for performing density functional theory calculations to obtain the relaxed structures of oxygen-functionalized pores. The plane-wave basis sets were employed to carry out the electronic wave function expansion with the cutoffs of 50 Ry and 500 Ry employed for the wave function and charge density, respectively. Perdew-Bruke-Ernzerhof functional was used to describe the exchange-correlation, and ultrasoft pseudopotentials 72 were utilized to model the interactions between the ionic core and valence electrons. A vacuum of 2.0 nm was incorporated along the direction normal to the oxygen-functionalized pores' surface to avoid interactions between the periodic images. Owing to the large supercell, the Brillouin zone sampling was restricted to the Γ point, and the Broyden-Fletcher-Goldfar-Shanno scheme was employed to perform structural relaxation until the Hellmann-Feynman forces were less than 10 -3 Ry Bohr -1 .