An Experimental and Theoretical Study on The S-doped g-C3N4 Nanosheets

Using sunlight as a permanent energy source and free of contamination in photocatalyticprocesses is the best solution to solve the energy crisis and environmental pollution. In recentyears, g-C3N4 (graphitic carbon nitride) has been considered as a visible light photocatalyst. It islow-cost and biocompatible photocatalyst with high thermal and chemical stability [1]. It is usedin various photocatalytic fields such as water splitting, CO2conversion to fuel, degradation ofpollution. However, the photocatalytic activity of g-C3N4 is not significant, due to the relativelylarge band gap and high recombination rate of e--h pairs. In this work, S-doped modificationmethod is used to improve the g-C3N4 photocatalytic efficiency, which is examined theoreticallyand experimentally. Both bare and S-doped g-C3N4 nanosheets were synthesized by thermalcondensation technique. The XRD patterns and FT-IR spectra confirmed the synthesis of the g-C3N4 structure for bare and S-doped g-C3N4. ICP-AES analysis confirmed the presence of sulfurin the S-doped g-C3N4.TEM and SEM image for g-C3N4 showed layer structure of g-C3N4nanosheet. UV-vis spectra and Tauc plots showed that sulfur doping of the g-C3N4 decreasesband gap and increases visible light absorption.DFT calculation showed that doping of g-C3N4with sulfur decreases band gap and thus visible light absorption is modified. On the other hand, Sdoping increases delocalization and photogenerated carriers can freely move between heptazineunits that decreases recombination rate of e--h pairs. Generally, experimental and theoreticalresults indicate that S doping of g-C3N4 improves the photocatalytic activity of the g-C3N4.

کلیدواژه ها:

g-C3N4 Nanosheet ، Photocatalytic Efficiency ، Visible Light