Selective spin injection of g-SiC6 monolayer for dioxygen activation

Activation of molecular O2 is an important but difficulty step in many catalytic processes owing to the fact that a spin-flip based activation is normally required to transfer O2 from the triplet ground state to singlet state. Here, we report a new O2 activation mechanism, in which the catalyst can inject electrons with selective spins into O2 to directly result in a highly activated spin state. Our results show that the nonmagnetic g-SiC6 monolayer possesses a strong O2 binding, and the Si of g-SiC6 varies from sp2 to sp3 hybridization with the O2 incoming and injects electrons with antiparallel spins into the O2 with a super low energy barrier. The resulted high-activated spin state directly triggers the dissociation of bridge-on adsorbed O2 to *O with a very low activation energy of 0.09 eV. Further studies demonstrate that a CO molecule can be adsorbed by the activated O2 and the derived *O, and then be oxidized to CO2 subsequently. The weak adsorption of CO and CO2 prevents the poisoning of g-SiC6 by CO and promotes the catalyst regeneration. Our findings enriches the mechanistic understanding of oxygen reduction reaction and shed new light on the design of nonmagnetic metal-free catalysts for O2-activation.

Automated summary

In this study, a new mechanism for oxygen activation is reported, in which a catalyst injects electrons with selective spins into oxygen, resulting in a highly activated spin state. The activated oxygen can then adsorb CO molecules and oxidize them to CO2. The weak adsorption of CO and CO2 prevents catalyst poisoning and promotes catalyst regeneration. These findings enhance the understanding of the mechanistic of oxygen reduction reaction and provide insights for the design of nonmagnetic metal-free catalysts for oxygen activation.