Organic–inorganic hybrid photocatalyst consisting of a highly conjugated metal complex and graphitic carbon nitride for efficient hydrogen evolution and Cr(vi) reduction

Abstract

Copper tetraphenylporphyrin tetrasulfonic acid (Cu-Por) metal complex is anchored over graphitic carbon nitride (GCN) sheets by electrostatic interaction. The incorporation of a photosensitizer through π–π interactions greatly enhanced the light absorption capacity and inhibited the recombination of photogenerated charge carriers as evident from PL, TR-PL, and photoelectrochemical analyses. The Cu-Por/GCN catalyst showed 4.1 mmol g⁻¹ h⁻¹ H₂ evolution, which was 6.8 times higher than that of GCN, and a high AQY of 65.1% upon irradiation with a 400 W metal halide bulb. The high conjugation of the porphyrin ring extended the light absorption of GCN toward the red region of visible light spectra with only 0.6% copper concentration. This photocatalyst was also observed to effectively reduce 98.1% of carcinogenic Cr(VI) to Cr(III) as opposed to 25.4% in the case of GCN in 35 min.