S-Modified Graphitic Carbon Nitride with Double Defect Sites For Efficient Photocatalytic Hydrogen Evolution

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Graphitic carbon nitride (g-C3N4) shows promise for solar energy conversion but suffers from poor light absorption and charge carrier recombination.
• Defect engineering and atomic doping are effective strategies to enhance the electronic structure and performance of g-C3N4.

Purpose of the Study:

• To improve the photocatalytic hydrogen evolution efficiency of graphitic carbon nitride (g-C3N4) under visible light.
• To investigate the effects of sulfur doping and defect engineering on the electronic structure and charge transport properties of g-C3N4.

Main Methods:

• Synthesized sulfur-doped, double-deficient graphitic carbon nitride (SDCN) via a defect engineering strategy.
• Characterized the material's structure, electronic properties, and photocatalytic activity.
• Employed experimental techniques and theoretical calculations to elucidate charge separation and transfer mechanisms.

Main Results:

• The synthesized SDCN exhibited abundant unsaturated sites and cyano groups, promoting interlayer bonding and charge transport.
• Sulfur doping tuned the electronic structure and enhanced visible light absorption through C-S-C bond formation.
• SDCN achieved a photocatalytic hydrogen evolution rate of 1613.5 µmol g⁻¹ h⁻¹, which is 31.5 times higher than pristine MCN (51.2 µmol g⁻¹ h⁻¹).

Conclusions:

• The S-modified double-deficient site strategy effectively enhances g-C3N4's photocatalytic performance for hydrogen evolution.
• Optimized electronic structure, improved light absorption, and efficient charge separation are key to the enhanced efficiency.
• The cyano groups act as electron traps, facilitating the reduction of H+ to hydrogen.