Fe-doped and -mediated graphitic carbon nitride nanosheets for enhanced photocatalytic performance under natural sunlight

Herein, we demonstrate the synthesis of highly efficient Fe-doped graphitic carbon nitride (g-C₃N₄) nanosheets via a facile and cost effective method. The synthesized Fe-doped g-C₃N₄ nanosheets were well characterized by various analytical techniques. The results revealed that the Fe exists mainly in the +3 oxidation state in the Fe-doped g-C₃N₄ nanosheets. Fe doping of g-C₃N₄ nanosheets has a great influence on the electronic and optical properties. The diffuse reflectance spectra of Fe-doped g-C₃N₄ nanosheets exhibit red shift and increased absorption in the visible light range, which is highly beneficial for absorbing the visible light in the solar spectrum. More significantly, the Fe-doped g-C₃N₄ nanosheets exhibit greatly enhanced photocatalytic activity for the degradation of Rhodamine B under sunlight irradiation. The photocatalytic activity of 2 mol% Fe-doped g-C₃N₄ nanosheets is almost 7 times higher than that of bulk g-C₃N₄ and 4.5 times higher than that of pure g-C₃N₄ nanosheets. A proposed mechanism for the enhanced photocatalytic activity of Fe-doped g-C₃N₄ nanosheets was investigated by trapping experiments. The synthesized photocatalysts are highly stable even after five successive experimental runs. The enhanced photocatalytic performance of Fe-doped g-C₃N₄ nanosheets is due to high visible light response, large surface area, high charge separation and charge transfer. Therefore, the Fe-doped g-C₃N₄ photocatalyst is a promising candidate for energy conversion and environmental remediation.