(544eh) Computational and Experimental Investigations of Electrochemical CO2 Reduction on a Well-Defined Model Surface

The electrochemical conversion of CO₂ into value-added chemicals, such as carbon monoxide, hydrocarbons and alcohols, using renewable energy sources provides a promising option to alleviate environmental problems caused by the greenhouse effect.¹ To achieve this, a sustainable and efficient catalyst which operates at low potential bias is in great need. Many catalysts are able to reduce CO₂ to CO with high efficiency. However, only Cu shows mediocre activities in producing further reduced products such as methane and ethylene.^2-5 CO was confirmed in both experimental and theoretical work as the key intermediate in reducing CO₂ to hydrocarbons and oxygenates^6-9. Therefore, to manipulate surface adsorbed CO can be a viable route to direct CO₂ reduction reaction towards more desired products.

Herein we report both computational and experimental investigations of electrochemical CO₂ reduction on a well-defined model surface constructed with Cu and CO-productive materials (i.e. Au and Ag). We found that CO produced by Au or Ag would migrate to Cu with low activation energy and reduced further by Cu. Also, we proved that sufficient CO supply to Cu surface is critical for methane and ethylene production. Compared to pure bulk Cu catalyst, our results showed a better CH₄ selectivity and activity over hydrogen evolution reaction (HER) with the introduction of CO-productive materials.^{10, 11} Such enhancement is attributed to the abundance of CO on Cu surface provided by Au or Ag and is supported by both DFT experimental evidence. Based on these results, discussions on mechanism understandings and catalyst design principles are made for achieving more advanced CO₂ electroreduction performance.

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