Defect‐Assisted Covalent Binding of Graphene to an Amorphous Silica Surface: A Theoretical Prediction

Abstract

We propose a mechanism for defect-assisted covalent binding of graphene to the surface of amorphous silica (a-SiO(2)) based on first-principles density functional calculations. Our calculations show that a dioxasilirane group (DOSG) on a-SiO(2) may react with graphene to form two Si-O-C linkages with a moderate activation barrier (≈0.3 eV) and considerable exothermicity (≈1.0 eV). We also examine DOSG formation via the adduction of molecular O(2) to a silylene center, which is an important surface defect in a-SiO(2) , and briefly discuss modifications in the electronic structure of graphene upon the DOSG-assisted chemical binding onto the a-SiO(2) surface.

Detection of Low-Density Surface Sites on Silica: Experimental Evidence of Intrinsic Oxygen-Vacancy Defects

“…Using this approach, sufficient densities of various defect sites could be prepared on high surface area silica to enable characterization of these sites using IR and photoluminescence (PL) spectroscopies. − However, intrinsic defect sites are much more difficult to detect. Because of the challenge of experimentally detecting low-density intrinsic defect sites on the silica surface, computational studies of such sites have been performed. − Kuo and Hwang found that a surface OVD is capable of transforming from a Si–Si dimer to other reactive structures, including silylene and silanone sites …”