Gold Nanoparticles for CO₂ Electroreduction: An Optimum Defined by Size and Shape.

Area of Science:

• Nanotechnology
• Electrochemistry
• Catalysis

Background:

• Nanoparticle size critically influences catalytic activity and selectivity.
• Optimizing nanoparticle catalysts is essential for efficient chemical transformations.
• Gold nanoparticles are promising electrocatalysts for CO2 reduction.

Purpose of the Study:

• To investigate the size-dependent selectivity of gold nanoparticles for CO2 electroreduction.
• To identify the optimal nanoparticle size for maximizing CO production.
• To understand the structural factors governing CO2 electroreduction selectivity.

Main Methods:

• Synthesis of size-selected gold nanoparticles (1.5–6.5 nm).
• Electrochemical evaluation of CO2 reduction performance.
• High-resolution transmission electron microscopy (HRTEM) for structural analysis.

Main Results:

• An optimal gold nanoparticle size of approximately 3 nm was identified for CO2 electroreduction.
• Maximized selectivity toward carbon monoxide (CO) with up to 60% Faradaic efficiency at low potentials.
• Multiply twinned nanoparticles, featuring pinned 8-fold coordinated sites, were found to be favorable for CO production.

Conclusions:

• Nanoparticle size and shape are critical parameters for tuning CO2 electroreduction selectivity.
• Optimizing the abundance of 8-fold coordinated surface sites is a viable strategy for enhancing CO production.
• This research advances nanocatalyst design for efficient CO2 conversion into valuable products.