Theory-Guided Screening of Binary Alloy Thin Films for Electrochemical Reduction of Carbon Dioxide

Electrochemical reduction of CO₂ is an interesting pathway towards sustainability, as it enables the use of CO₂ as a feedstock for the production of renewable fuels and chemicals, provided that the energy is supplied from renewable energy sources. There have been numerous reports on different catalyst systems that enable efficient and selective production of two-electron reduction products. On the other hand, only Cu has displayed any propensity as a catalyst to electrochemically reduce CO₂ into longer chain hydrocarbons, carboxylates, and alcohols, while requiring large overpotential and showing poor product selectivity. Recent theoretical work indicates that scaling relations associated with reaction adsorbate binding energies could be limiting the CO₂ reduction activity of transition metal catalysts for the production of further reduced products.[1] These studies suggest that alloying can improve the activity and selectivity of a CO₂ reduction catalyst by decoupling the binding energies of specific reaction intermediates.

Here, we report on our effort on the screening of CO₂ reduction activity of a targeted library of binary alloy thin films synthesized through physical vapor deposition. Activity trends associated with the adsorbate binding energies of the alloy components are discussed. The focus will be put on synergistic effects observed for a few of the alloys, namely AuPd, PtIn, and PdIn alloys. These alloys demonstrate how alloying can engender new electrocatalytic properties beyond the sum of the components.

 [1] Peterson, A.A.; Nørskov, J.K., "Activity Descriptors for CO₂ Electroreduction to Methane on Transition-Metal Catalysts," J. Phys. Chem. Lett., 2012, 3, 251-258.