Visible Light-Driven Highly Selective CO₂ Reduction to CH₄ Using Potassium-Doped g-C₃N₅

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Developing efficient artificial photocatalytic systems for solar energy conversion is crucial for clean energy and environmental protection.
• Carbon nitride materials, like g-C3N4, are promising for CO2 conversion but have limitations.

Purpose of the Study:

• To explore the potential of a novel low-Z nitrogen-rich carbon nitride, g-C3N5, for photocatalytic CO2 conversion under visible light.
• To investigate the effect of potassium (K) doping on the performance and stability of g-C3N5 for CO2 conversion.

Main Methods:

• Synthesis and characterization of g-C3N5 and K-doped g-C3N5.
• Photocatalytic CO2 conversion experiments under visible light without sacrificial reagents.
• Density functional theory (DFT) calculations to elucidate the mechanism.

Main Results:

• g-C3N5 demonstrated significantly enhanced CH4 production rates compared to g-C3N4.
• g-C3N5 achieved 100% selectivity for CH4, a substantial improvement over g-C3N4's 21%.
• 1% K doping in g-C3N5 further improved performance and photostability without compromising selectivity.

Conclusions:

• g-C3N5 is a highly efficient and selective material for solar-driven CO2 to CH4 conversion.
• Potassium doping is an effective strategy to enhance the photocatalytic activity and stability of g-C3N5.
• DFT analysis provides insights into the improved photocatalytic mechanism of K-doped g-C3N5.