Can Si-doped graphene activate or dissociate O2 molecule?

Recently, the adsorption and dissociation of oxygen molecule on a metal-free catalyst has attracted considerable attention due to the fundamental and industrial importance. In the present work, we have investigated the adsorption and dissociation of O2 molecule on pristine and silicon-doped graphene, using density functional theory calculations. We found that O2 is firstly adsorbed on Si-doped graphene by [2 + 1] or [2 + 2] cycloaddition, with adsorption energies of −1.439 and −0.856 eV, respectively. Following this, the molecularly adsorbed O2 can be dissociated in different pathways. In the most favorable reaction path, the dissociation barrier of adsorbed O2 is significantly reduced from 3.180 to 0.206 eV due to the doping of silicon into graphene. Our results may be useful to further develop effective metal-free catalysts for the oxygen reduction reactions (ORRs), thus greatly widening the potential applications of graphene.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (51 K)Download as PowerPoint slideHighlights► The dissociation of O2 molecule on the pristine graphene is unfavorable both dynamically and thermodynamically. ► After Si-doping, O2 is firstly adsorbed on this graphene by [2 + 1] cycloaddition, with adsorption energy of −1.439 eV. ► Following this step, the adsorbed oxygen molecule can be easily dissociated with a barrier of 0.206 eV, which is much smaller than that of pristine graphene (3.180 eV).