Fig. 3: Reactions between CO and H2 on CoMnOx crystal NPs.
a Schematic illustration of the reaction cell used for operando reaction studies using TEY-XAS. The yellow circles represent CoMnOx NPs on a gold foil covering a Si wafer. b O K-edge XAS of CoMnOx before (black), after CO exposure (red), and after H2 introduction (blue). The peak a 531 eV is due to lattice O in CoMnOx. The peak at 534 eV corresponds to the X-rays excitation of electrons from the O 1s level of CO to the antibonding orbital (π*). This peak has contributions from the molecular CO adsorbed on Co0, and from carbonates on CoMnOx. The broad peak around 540 eV is due to transitions to unoccupied σ* bands35, which disappear due to adsorbed CO donating electrons to these orbitals. After introduction of H2, the peak at 534 eV decreases due to H2-assisted CO dissociation, leaving only contributions from the carbonate species. c Time evolution (2 min intervals) of the CO π* peak intensity under 1 bar of H2 flowing at 2.5 mL/min at 150 °C. d Intensity of the CO π* orbital peak as function of time for three temperatures, which measures the H2-CO reaction rate. e Arrhenius plot from the π* orbital peak intensity decay rate.
