Tailoring Advanced N-Defective and S-Doped g-C₃N₄ for Photocatalytic H₂ Evolution

Although challenges remain, synergistic adjusting various microstructures and photo/electrochemical parameters of graphitic carbon nitride (g-C3N4) in photocatalytic hydrogen evolution reaction (HER) are the keys to alleviating the energy crisis and environmental pollution. In this work, a novel nitrogen-defective and sulfur-doped g-C3N4 (S-g-C3N4-D) is designed elaborately. Subsequent physical and chemical characterization proved that the developed S-g-C3N4-D not only displays well-defined 2D lamellar morphology with a large porosity and a high specific surface area but also has an efficient light utilization and carriers-separation and transfer. Moreover, the calculated optimal Gibbs free energy of adsorbed hydrogen (Delta G(H*)) for S-g-C3N4-D at the S active sites is close to zero (approximate to 0.24 eV) on the basis of first-principle density functional theory (DFT). Accordingly, the developed S-g-C3N4-D catalyst shows a high H-2 evolution rate of 5651.5 mu mol g(-1) h(-1). Both DFT calculations and experimental results reveal that a memorable defective g-C3N4/S-doped g-C3N4 step-scheme heterojunction is constructed between S-doped domains and N-defective domains in the structural configuration of S-g-C3N4-D. This work exhibits a significant guidance for the design and fabrication of high-efficiency photocatalysts.