Rare earth element, Sm, modified graphite phase carbon nitride heterostructure for photocatalytic hydrogen production

Photocatalytic nanomaterials of rare earth metal modified graphitic carbon nitride (g-C3N4) were successfully prepared using a simple hydrothermal ion exchange method. As a high activity photocatalyst, the hydrogen evolution amount of the samarium(iii) oxide@nickel sulfide-graphitic carbon nitride (Sm2O3@Ni7S6/g-C3N4) catalyst is nearly 3 mmol g(-1) h(-1) after visible light irradiation for 3 h, which was much more than the amount obtained using the Ni7S6/g-C3N4 catalyst. The characteristics of Sm2O3@Ni7S6/g-C3N4 were determined using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy (UV-vis), fluorescence spectra and so on. The results showed that the deposited Sm2O3@Ni7S6 was uniformly dispersed on the g-C3N4 sheet, and the Sm2O3@Ni7S6 was used as a cocatalyst to improve the electron transfer rate and hydrogen production rate, and reduce the compound rate of electrons and holes in the composite material. There was a strong synergy between Sm2O3@Ni7S6 and g-C3N4, which improved the photocatalytic performance. The UV-vis spectra showed that the absorption range of Sm2O3@Ni7S6/g-C3N4 was enlarged, and the forbidden band width was smaller. The Brunauer-Emmett-Teller results showed that Sm2O3@Ni7S6/g-C3N4 had a greater specific surface area and pore volume, which were beneficial for the adsorption of dye molecules and enhanced the photocatalytic activity. Therefore, rare earth metal samarium oxides might be a potential cocatalyst for the design of a new photocatalyst in the photocatalysis field.