Sulfur-\nand Strontium-Doped\nGraphitic Carbon Nitride\nfor Efficient Photocatalytic Hydrogen Evolution

Abstract

Doping\nmetallic and nonmetallic elements in the graphitic\ncarbon\nnitride (g-C₃N₄) molecular layer to tune its\nband structure is an important strategy for improving its photocatalytic\nactivity. Herein, sulfur- and strontium-doped g-C₃N₄ catalysts are synthesized by calcining the mixture of urea,\n2-thiobarbituric acid, and strontium chloride hexahydrate at elevated\ntemperature. The optimal hydrogen production rate of 6Sr-SCN (SCN,\nsulfur-doped graphitic carbon nitride) reaches 13.9 μmol/h,\nabout 6.6 times that of pure g-C₃N₄, abridged\nas CN, under visible light irradiation with λ ≥ 420 nm.\nAn experimental study and theoretical simulation demonstrate that\nS and Sr doping narrows the band gap, forms an intraplane heterojunction,\nextends the harvest in the visible light range and the transport and\nseparation efficiency of photogenerated carriers, and increases molecular\nbuckling and specific surface area as well. All these factors are\nsynergistically combined to improve the photocatalytic performance\nof g-C₃N₄.