Enhanced visible light photocatalytic hydrogen evolution over porphyrin hybridized graphitic carbon nitride.

Tetra (4-carboxyphenyl) porphyrin (TCPP) was loaded on the surface of Pt/g-CN via a simple adsorption process, and the microstructure and chemical structure of the composites were characterized by high resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV-visible diffused reflectance spectroscopy and photoluminescence spectroscopy. Loading TCPP onto Pt/g-CN enhanced the visible-light-driven photocatalytic evolution of H from water. The TCPP/Pt/g-CN composite with a TCPP loading of 1wt% had the highest photoactivity, which was 2.1 times higher than that of Pt/g-CN. This improvement is attributed to enhanced visible light utilization by the TCPP/Pt/g-CN resulting from the strong visible light response of TCPP. In addition, the formed organic heterostructure between TCPP and g-CN with overlapping bad gaps accelerates the electron transfer and inhibits the recombination of the photogenerated electrons and holes on g-CN.