The development of inexpensive, easily prepared and efficient electrocatalysts for conversion of CO2 into valuable products is critical to reduce global CO2 emissions. Previous studies have shown that alloying multiple elements together can have a beneficial effect on the onset potentials for CO2 reduction, as well as promote the selective formation of products that the constituent metals cannot individually produce in appreciable amounts. In this work, we investigated the effect of alloying Sn, Pb, and Bi, each of which has been reported to be an efficient catalyst to electrochemically reduce CO2 in imidazolium-based room-temperature ionic liquid electrolytes. In this presentation, we will document the ability of a commercially available alloy, Bi50Sn22Pb28, which is known commonly as Rose’s Metal, to drive CO evolution in the presence of MeCN electrolyte solutions that contain [BMIM]OTf. The Rose’s metal alloy is a selective (90%) and robust platform for CO evolution with partial current density of jCO = 4.5 mA/cm2 at –1.95 V vs SCE. We will also demonstrate that the rate of CO2 reduction with the Bi/Sn/Pb alloy can be correlated to the activity of the constituent elements. Addition of water into the imidazolium-based electrolyte leads to a potential dependent switch in CO2 reduction selectivity. Incremental amounts of added water (1 to 5% by volume) are found to switch the selectivity from predominantly CO to formate with negligible H2 evolution, especially at lower potentials. The extent to which controlling the alloy composition and the proton availability at the catalyst surface can allow for the selectivity and the activity of CO2 reduction to be tuned will be discussed.

Efficient CO2 reduction using the bismuth alloy Rose’s metal in the presence of room-temperature ionic liquid electrolytes

256th National Meeting (2018)

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