Nanoporous Cu-O system catalysts with different oxidation states of Cu have been fabricated through a combination of dealloying of as-milled Al 66.7 Cu 33.3 alloy powders with subsequent thermal annealing. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) have been used to characterize the microstructure and surface chemical states of Cu-O catalysts. The peculiar nanoporous structure can be retained in Cu-O catalysts after thermal treatment. Catalytic experiments reveal that all the Cu-O samples exhibit a complete CO 2 conversion below 170 o C. The optimal catalytic performance could be achieved through the combination of annealing in air with hydrogen treatment for the Cu-O catalyst, which shows near complete conversion temperature (T 90% ) of 132 o C and activation energy of 91.3 KJ mol -1 . In addition, the present strategy (ball milling, dealloying and subsequent thermal treatment) could be scaled up to fabricate high-performance Cu-O catalysts towards CO oxidation.
Ag-Zn alloys are identified as highly active and selective electrocatalysts for CO2 reduction reaction (CO2RR), while how the phase composition of the alloy affects the catalytic performances has not been systematically studied yet. In this study, we fabricated a series of Ag-Zn alloy catalysts by magnetron co-sputtering and further explored their activity and selectivity towards CO2 electroreduction in an aqueous KHCO3 electrolyte. The different Ag-Zn alloys involve one or more phases of Ag, AgZn, Ag5Zn8, AgZn3, and Zn. For all the catalysts, CO is the main product, likely due to the weak CO binding energy on the catalyst surface. The Ag5Zn8 and AgZn3 catalysts show a higher CO selectivity than that of pure Zn due to the synergistic effect of Ag and Zn, while the pure Ag catalyst exhibits the highest CO selectivity. Zn alloying improves the catalytic activity and reaction kinetics of CO2RR, and the AgZn3 catalyst shows the highest apparent electrocatalytic activity. This work found that the activity and selectivity of CO2RR are highly dependent on the element concentrations and phase compositions, which is inspiring to explore Ag-Zn alloy catalysts with promising CO2RR properties.
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