Screening of material libraries for electrochemical CO2 reduction catalysts - Improving selectivity of Cu by mixing with Co

•Selectivity and activity of CO2 reduction are screened by SFC-OLEMS.•Product distribution is dependent from potential/current and catalyst composition.•Impact of various compositions of Cu-Co catalysts is investigated.•Thin film composition spread samples ensure constant surface structure.•Selectivity shifts from C1 to C2 products for a Co concentration of 5-15 at.%.

The efficiency of the direct electrochemical CO2 reduction can be improved by the development of new alloy catalysts, but to do so a highly resolved composition screening remains to be connected to complex sample preparation and time consuming analysis. We have developed a technique that allows a fast and easy initial catalyst composition screening by analyzing thin film composition spread samples, utilizing a scanning flow cell coupled to an online electrochemical mass spectrometer (SFC-OLEMS). As a first case example, the investigation of a Cu-Co thin film material library demonstrates the benefits and high potential of this approach. In particular, a shift in selectivity toward C2 species for low Co content (5-15 at.%) has been found and is discussed as being related to changed adsorption energies of intermediate products and the consequent modification of reaction pathways.

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