Electrochemical CO₂ conversion to value-added chemicals and fuels by using renewable electricity is a sustainable way to fulfill world’s ever increasing energy demands and close the anthropogenic carbon cycle. However, this process is thermodynamically uphill and kinetically sluggish for production of multi-carbon (C₂₊) products. Therefore, it is crucial to develop a highly active and selective catalyst to minimize the input energy and boost the product formation. Despite numerous studies to improve activity and selectivity of copper (Cu) and Cu-based catalysts known as the best catalysts for this reaction the production of high energy density C₂₊ products is still at the early stages of the development for practical realization.

Here, we present high index facet bimetallic Cu nanocrystals (Cu-HI), synthesized in a controlled precipitation fashion, as efficient electrocatalysts with high selectivity and activity for propanol production. Cu-HI has a greater number of undercoordinated step and kink atoms at the surface that significantly lower the energy barrier for C₂₊ oxygenate production. The electrocatalytic performance of the synthesized Cu-HI electrocatalyst was studied in a three-compartment cell using 1 M KOH electrolyte and compared to low index Cu nanocrystals facets such as [100], [111], and [110]. The results for Cu-HI, show an overall C₂₊ and n-propanol formation with faradaic efficiency of about 80% and 30%, respectively. Moreover, different physicochemical and electrochemical characterization techniques such as X-ray diffraction (XRD), scanning transition electron microscopy (STEM), X-ray photoelectron spectrometry (XPS), and in-situ Raman spectroscopy were performed to study the morphology and atomic structure of the synthesized nanocrystals and deconvolute the effect of different facets on the selectivity and activity of eCO₂RR.