Insight into the mechanism of direct N-C coupling in selective catalytic reduction of NO by CO over Ni(111)-supported graphene

Selective catalytic reduction (SCR) of NO using CO as a reducing agent is a straightforward and promising approach to the simultaneous removal of NO and CO. Herein, a novel mechanism of N-C direct coupling of gaseous NO and CO into ONCO and subsequent hydrogenation of *ONCO to nitrogen-containing compounds over Ni(111)-supported graphene ((Gr/Ni(111)) is reported. The results indicate that Gr/Ni(111) can not only trigger direct N-C coupling of NO and CO to form ONCO with a low activation energy barrier of 0.11 eV, but also enable the key intermediate of *ONCO to be stable. The *ONCO chemisorbed on Gr/Ni(111) exhibits negative univalent [ONCO]- and is more stable than neutral ONCO. The hydrogenation pathways show that HNCO preferably forms through a kinetically favorable initial N-C coupling due to the lowest free-energy barrier of 0.18 eV, while NH2CH3 is a considerably competitive product because its free-energy barrier is only 0.20 eV higher than that of HNCO. Our results provide a fundamental insight into the novel reaction mechanism of the SCR of NO and also suggest that nickel-supported graphene is a potential and high-efficient catalyst for eliminating CO and NO harmful gases. A novel mechanism of direct N-C coupling of gaseous NO and CO into ONCO and subsequent hydrogenation of *ONCO into high value-added nitrogen-containing compounds over nickel-supported graphene for selective catalytic reduction of NO using CO as a reducing agent.

Automated summary

This study reports a novel mechanism of direct N-C coupling of gaseous NO and CO into ONCO and subsequent hydrogenation of *ONCO into nitrogen-containing compounds over nickel-supported graphene. The results show that Gr/Ni(111) can trigger the N-C coupling with a low activation energy barrier and stabilize the key intermediate *ONCO. The study also suggests that nickel-supported graphene is a potential and efficient catalyst for the simultaneous removal of CO and NO.