Visible light enhanced thermocatalytic CO + NO reaction over metastable NiCo2O4 catalyst

Abstract A NiCo2O4 catalyst was evaluated for CO + NO reaction under a photo-thermal synergistic effect. Compared with crystalline samples, metastable NiCo2O4 with a crystalline/amorphous heterostructure exhibited higher catalytic activity due to its better low temperature reducibility and more oxygen vacancies (VOs). The collective TPR, XPS, and in-situ DRIFTS results revealed that more VOs induced by CO directly interacting with the lattice oxygen of NiCo2O4 could promote NO adsorption and activation, and visible light irradiation further reinforced the above processes by facilitating CO to capture lattice oxygen and enriching electrons in VOs. With the increase in reaction temperature, the electron-rich VOs could further drive NO dissociation into N2. Herein, the VOs was not only an active center of catalytic reaction, but also acted as a bridge between CO and NO for lattice oxygen circulation. Thus, a photo-thermal synergistic effect for NO reduction by CO occurred over metastable NiCo2O4.