Watching Visible Light-Driven CO₂ Reduction on a Plasmonic Nanoparticle Catalyst.

Area of Science:

• Photocatalysis
• Renewable Energy
• Surface Chemistry

Background:

• Visible light photocatalytic reduction of carbon dioxide (CO2) offers a route to renewable fuel production, mimicking natural photosynthesis.
• Understanding reaction dynamics on photocatalyst surfaces is crucial for enhancing efficiency and selectivity in artificial photosynthesis.

Purpose of the Study:

• To investigate the dynamics of plasmonic silver (Ag) photocatalysts during visible light-driven CO2 reduction at the single-nanoparticle level.
• To identify key intermediates and reaction pathways involved in CO2 conversion.

Main Methods:

• In situ surface-enhanced Raman spectroscopy (SERS) was employed to capture dynamic adsorbates and products on individual Ag nanoparticles.
• Density functional theory (DFT) simulations were used to analyze the electronic structure and interactions of captured adsorbates.

Main Results:

• Single-nanoparticle SERS revealed discrete adsorbates and products, with a prominent surface-adsorbed hydrocarboxyl (HOCO*) intermediate.
• DFT simulations elucidated the mechanism of plasmonic excitation activating physisorbed CO2 to form HOCO*.
• The study highlights the interplay between photoexcited states and adsorbate/metal interactions in CO2 reduction.

Conclusions:

• The hydrocarboxyl (HOCO*) intermediate is critical for the reduction of CO2 to carbon monoxide (CO) and formic acid (HCOOH).
• Plasmonic excitation in silver nanoparticles plays a key role in activating CO2 and facilitating its conversion.
• This work provides fundamental insights into light-driven CO2 reduction mechanisms for potential fuel production.