Phase Segregated Bimetallic Alloys As Electrocatalysts for Electrochemical Carbon Dioxide Reduction
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Operating in tandem with renewable electricity supplies (i.e., wind or solar), electrochemical synthesis of chemical and fuel products from carbon dioxide (CO2) represents a sustainable method to fuel the energy needs of society. The primary shortcoming of this technology is the lack of catalysts that are both sufficiently active and selective. The ability to produce further reduced (> 2 electron) fuels and chemicals, such as hydrocarbons, alcohols and carbonyls, is most attractive from an economic standpoint. Catalyst surface structure engineering or alloying are both effective strategies to favour selectivity towards these targeted compounds. More specifically, our group’s catalyst material discovery efforts on bimetallic alloys have been capable of controlling selectivity of various CO2 reduction products, owing to the effects that alloying has on the adsorption energies of key reaction intermediates. A notable drawback of many bimetallic systems however is that their low alloy formation energies cause them to segregate under the reactive conditions encountered during CO2reduction [1]. This results in an enriched surface layer of the less reactive element, and a consequential loss of the benefits achieved through alloying. In this work we turn to a new class of bimetallic CO2 reduction catalysts, consisting of elements that are immiscible on the bulk scale. These phase segregated systems (Figure 1A) are employed in an attempt to tailor catalyst selectivity towards further reduced products. Thin films of these catalysts are prepared and tested in our custom designed electrochemical cell (Figure 1B) that allows excellent detection capabilities towards liquid based products such as alcohol and carbonyl compounds [2]. We show that by employing phase segregated systems with varying compositions and constituent elements we are able to tune the selectivity of bimetallic CO2reduction electrocatalysts. [1] H. Hansen, C. Shi, A. Lausche, A. Peterson, J. Norskov, Phys. Chem. Chem. Phys., 2016, 18, 9194. [2] K. Kuhl, E. Cave, D. Abram, T. Jaramillo, J. Amer. Chem. Soc., 2012, 5, 7050.Figure 1
