DFT Study on Sulfur-Doped g-C3N4 Nanosheets as a Photocatalyst for CO2 Reduction Reaction
2018
Wang, Yuelin | Tian, Yu | Yan, Likai | Su, Zhongmin
Graphitic carbon nitride (g-C₃N₄) can be used as a photocatalyst to reduce CO₂. Doping is an efficient strategy for improving the photocatalytic activity and tuning the electronic structure of g-C₃N₄. The sulfur-doped g-C₃N₄ (S-doped g-C₃N₄) as a promising photocatalyst for CO₂ reduction was investigated by density functional theory methods. The electronic and optical properties indicate that doping S enhances the catalytic performance of g-C₃N₄. From the reduction Gibbs free energies, the optimal path for CO₂ reduction reaction to CH₃OH production catalyzed by S-doped g-C₃N₄ is CO₂ → COOH* → CO → HCO* → HCHO → CH₃O* → CH₃OH. In comparison with g-C₃N₄, doping S can alter the rate-determining step and reduce the Gibbs free energy from 1.43 to 1.15 eV. CO₂ reduction activity of S-doped g-C₃N₄ is better than that of g-C₃N₄, which is in well agreement with the experimental results. Our work provides useful insights into designing nonmetal-doped g-C₃N₄ for photocatalytic CO₂ reduction reactions.
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