Artificial photosynthesis, which stores solar energy into chemical bonds, has become one of the major research areas among all the efforts to use renewable energy to alleviate the energy crisis. Reducing carbon dioxide, using solar power, to valuable fuels can lead to a sustainable energy cycle where an adequate balance is maintained between energy consumption and its production. However, due to the intrinsic difficulties of the reaction, reducing carbon dioxide effectively is still a major challenge in artificial photosynthesis. Not only are we limited in terms of understanding the reaction pathways for CO2 reduction, but because of that we do not have the sufficient knowledge to design catalysts with high activity and selectivity. Therefore, understanding the structural factors of catalysts that govern the reaction pathway in CO2 reduction is critical for its success. Using nanoparticle catalysts, which have advantages in both fundamental and practical aspects, we have tried to identify the parameters essential to the engineering of active sites for CO2 reduction. Gold-copper bimetallic nanoparticles were tuned in composition and their activity for CO2 reduction was correlated with their structure. From the composition-dependent activity, we were able to find that the two important factors related to intermediate binding, the electronic effect and the geometric effect, dictate the activity for CO2 reduction. By considering the effect of these two factors on the binding strength of major intermediates, we were able to explain the trend in activity and selectivity observed for gold-copper bimetallic catalysts. The insights learned from this work, which should be applicable to a wide range of catalysts, allow us to synthesize copper based bimetallic nanoparticles with tunability in their electronic structure to enhance multiple proton and electron transfers for products like hydrocarbons. This presentation will focus on the identification of structural parameters for the design of CO2 reduction catalysts and their application to developing efficient catalysts with high selectivity for complex products.

Nanoparticle catalyst design for electrochemical reduction of carbon dioxide

249th National Meeting (2015)

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