CO₂ Overall Splitting by a Bifunctional Metal-Free Electrocatalyst

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Photo/electrochemical CO2 splitting is crucial for sustainable energy, but hindered by inefficient catalysts for CO2 reduction (CDRR) and water oxidation.
• Developing cost-effective, metal-free catalysts is essential to overcome current limitations.

Purpose of the Study:

• To develop a novel, metal-free bifunctional catalyst for efficient CO2 reduction and water oxidation.
• To investigate the performance of a silicon and nitrogen co-doped carbon (SiNC) nanomaterial in photo/electrochemical CO2 splitting.

Main Methods:

• Facile pyrolyzation was used to synthesize a porous silicon and nitrogen co-doped carbon (SiNC) nanomaterial.
• SiNC was employed as a metal-free bifunctional electrocatalyst in CO2 splitting reactions.
• A photovoltaic-driven CO2 splitting device with SiNC electrodes was constructed and tested.

Main Results:

• SiNC significantly enhanced CO2-to-CO and oxygen evolution reaction (OER) partial current densities by two orders of magnitude compared to single-doped materials.
• The photovoltaic-driven device achieved a high solar-to-chemical efficiency of 12.5% at a low overpotential (650 mV).
• Mechanism studies indicated the -Si(O)-C-N- unit in SiNC is the active site for simultaneous CDRR and OER.

Conclusions:

• The developed SiNC nanomaterial is a highly effective, metal-free bifunctional electrocatalyst for CO2 splitting.
• SiNC offers a promising pathway for efficient solar-to-chemical energy conversion through artificial photosynthesis.
• The unique electronic structure of SiNC facilitates low-energy adsorption of reaction intermediates, boosting catalytic activity.