Facet design promotes electroreduction of carbon dioxide to carbon monoxide on palladium nanocrystals.

Graphical abstract This paper describes the facet effect on Pd nanocrystals with the same size for CO 2 electroreduction. Highlights • Pd nanocrystals with three different facets were synthesized for CO 2 electroreduction. • A mechanism of facet effect on CO 2 electroreduction was proposed. • Pd concave cubes with {3 1 0} facets exhibited the highest CO Faradaic efficiency. • {3 1 0} facets facilitated COOH∗ formation and CO∗ desorption during the reaction. Abstract Highly selective electrochemical carbon dioxide reduction to valuable chemical products is a crucial approach to alleviate the energy crisis. To date, some noble metal based heterogeneous catalysts such as Pd exhibit high activity for electrochemical carbon dioxide reduction. However, few systematic studies of the active reaction site of these catalysts have been reported. This paper describes the facet effect on Pd nanocrystals with the same size for CO 2 electroreduction. The surface structure of Pd catalysts enclosed with {3 1 0}, {1 0 0} and {1 1 1} facets can be precisely controlled. The Pd concave cubes enclosed with high-index {3 1 0} facets show the highest CO Faradaic efficiency (FE) of 90.6%, compared with Pd cubes enclosed with {1 0 0} facets and Pd octahedrons enclosed with {1 1 1} facets. Density functional theory calculations reveal that the {3 1 0} facets of concave cubes boost the catalytic activity by facilitating the COOH∗ formation and the desorption of CO∗. [ABSTRACT FROM AUTHOR]