Direct coupling of alkanes via C-H activation of terminal methyl groups has acquired tremendous interests both scientifically and technically. Herein we present the results of linear alkane-coupling at the step edges of Cu surfaces at modulated temperatures. Combining the observations of scanning tunneling microscopy (STM) with density functional theory plus dispersion (DFT-D) calculations, we elucidate the mechanism of the reaction and demonstrate that the low activation barrier relies on heterogeneous catalysis at the upper step edges, where low-coordinated surface atoms are present. We further reveal the generality of the reaction, so that it can be applied on the step edges of different facets of surfaces.
Keywords: Cu step edges; STM; alkane; on-surface synthesis; polymerization.
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