Epitaxially grown silicon-based single-atom catalyst for visible-light-driven syngas production

Area of Science:

• Materials Science
• Catalysis
• Photochemistry

Background:

• Efficient photocatalysis requires improved active site dispersion and photon harvesting.
• Silicon's abundance and bandgap are attractive for photocatalysis, but its rigid structure and high formation energy pose challenges for metal integration.
• Previous attempts to combine silicon with metals for photocatalysis have been hindered by structural and energetic limitations.

Purpose of the Study:

• To develop a method for creating well-dispersed active sites on a silicon-based photocatalyst.
• To enhance photon utilization for photocatalytic applications.
• To achieve efficient carbon dioxide (CO2) conversion into syngas using a novel silicon-based material.

Main Methods:

• Employed a solid-state chemistry approach to synthesize crystalline silicon with dispersed cobalt (Co) atoms.
• Utilized in-situ formation of cobalt disilicide (CoSi2) nanodomains as seeds for epitaxial growth.
• Produced Co-incorporating silicon nanocrystals at the CoSi2/Si interface.

Main Results:

• Achieved isolated Co single-atom sites within silicon nanocrystals.
• Demonstrated high external quantum efficiency (10%) for CO2-to-syngas conversion.
• Reported CO and H2 yields of 4.7 and 4.4 mol/g(Co), respectively, with a tunable H2/CO ratio (0.8-2).
• Attained a turnover number of 2x10^4 for visible-light-driven CO2 reduction over 6 hours, exceeding previous single-atom photocatalysts by over tenfold.

Conclusions:

• The developed solid-state method enables the creation of highly dispersed single-atom catalysts on silicon.
• Cobalt-on-silicon single-atom catalysts show exceptional performance in visible-light-driven CO2 reduction to syngas.
• This work presents a promising pathway for designing advanced silicon-based photocatalysts for sustainable chemical transformations.