No abstract

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.

Bi is considered a highly active and selective electrocatalyst for CO2 reduction reaction (CO2RR), and Sb has great development potential. In this study, we fabricated a series of Bi-Sb alloy films by magnetron co-sputtering and further explored their electrocatalytic performances in CO2 reduction. In contrast to pure Sb catalyst, the Bi-Sb alloys substantially suppress HER and promote the pathway of CO2-to-formate. The formate selectivity increases with the increase of Bi content. When the content of Bi reaches about 40 at%, the Bi-Sb alloy exhibits the highest ability to convert CO2 to formate, and even shows a higher formate activity than that of pure Bi. In particular, the Bi45Sb55 catalyst exhibits a partial current density of formate formation of 58.0 mA cm-2 and a formate selectivity of 76.7 % at -1.0 V vs. RHE. A remarkable formate selectivity reaches up to over 95 % in the flow cell, and a formate current density of 500 mA cm-2 is achieved at a moderate overpotential of 859 mV, exhibiting great potential for CO2RR process to practical applications. The present work could provide guidelines for the design of Bi-Sb alloy catalysts for efficient CO2RR.