Interfacial oxygen vacancies at Co3O4-CeO2 heterointerfaces boost the catalytic reduction of NO by CO in the presence of O2

Abstract

Simultaneously improving both NOx conversion and N2 selectivity in the selective catalytic reduction of NO by CO (CO-SCR) under O2-containing conditions is highly challenging because of the competitive reactions of NOx and CO with O2. Here, we demonstrate that the interfacial oxygen vacancies (IOVs) generated at the Co3O4-CeO2 heterointerfaces by ball-milling-induced strain can remarkably boost both NOx conversion and N2 selectivity in the temperature range of 100–400 °C. The Co3O4-CeO2-IOV catalyst achieved approximately 100% NOx conversion and 100% N2 selectivity (200–350 °C, 1–5 vol% O2, and 20,000 h−1); even under 10 vol% O2, it still showed good catalytic performance. The spectroscopy analysis and theoretical calculations reveal that compared with O2 activation, IOVs are more favorable for the rate-limiting step of NO adsorption and dissociation. This work provides an effective strategy to create IOVs within metal oxide composite catalysts using ball-milling-induced interfacial strain for improving CO-SCR performance.