Hexagonal Close-Packed 2H-Cu Nanocrystals

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Tuning the morphology and structure of copper (Cu) nanomaterials is crucial for regulating their properties and applications.
• Synthesizing Cu nanomaterials with unconventional phases, beyond the stable face-centered cubic (fcc) phase, remains a significant challenge.

Purpose of the Study:

• To report a novel one-pot wet-chemical synthesis of Cu nanocrystals (NCs) with a hexagonal close-packed (hcp, 2H type) phase.
• To investigate the enhanced catalytic activity and selectivity of these 2H-Cu NCs in the electrochemical carbon dioxide reduction reaction (CO2RR).

Main Methods:

• One-pot wet-chemical synthesis to produce 2H-Cu NCs.
• Electrochemical carbon dioxide reduction reaction (CO2RR) measurements in a flow cell under alkaline conditions.
• In situ characterizations and density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• Successfully synthesized Cu NCs with an unconventional hcp (2H) phase.
• Achieved enhanced catalytic activity and selectivity for CO2RR, with a high Faradaic efficiency (FE) of 73.1% for multicarbon (C2+) products at 600 mA cm-2.
• Identified optimized adsorption of the *CO intermediate and a low energy barrier for C2+ product formation on 2H-Cu NCs via in situ studies and DFT.

Conclusions:

• Phase engineering of nanomaterials (PEN) strategy significantly improves CO2RR performance of Cu NCs.
• The 2H-Cu NCs offer a promising platform for efficient electrochemical CO2 conversion.
• This work opens avenues for exploring unconventional-phase nanomaterials and their intrinsic properties.