A Highly Active Star Decahedron Cu Nanocatalyst for Hydrocarbon Production at Low Overpotentials

The electrochemical carbon dioxide reduction reaction (CO 2 RR) presents a viable approach to recycle CO 2 gas into low carbon fuels. Thus, the development of highly active catalysts at low overpotential is desired for this reaction. Herein, a high‐yield synthesis of unique star decahedron Cu nanoparticles (SD‐Cu NPs) electrocatalysts, displaying twin boundaries (TBs) and multiple stacking faults, which lead to low overpotentials for methane (CH 4 ) and high efficiency for ethylene (C 2 H 4 ) production, is reported. Particularly, SD‐Cu NPs show an onset potential for CH 4 production lower by 0.149 V than commercial Cu NPs. More impressively, SD‐Cu NPs demonstrate a faradaic efficiency of 52.43% ± 2.72% for C 2 H 4 production at −0.993 ± 0.0129 V. The results demonstrate that the surface stacking faults and twin defects increase CO binding energy, leading to the enhanced CO 2 RR performance on SD‐Cu NPs.