Highly efficient photocatalytic H2 evolution from water over CdLa2S4/mesoporous g-C3N4 hybrids under visible light irradiation

Abstract

In this study, mesoporous graphitic carbon nitride (mpg-C3N4) nanosheets with high surface area (317 m2 g-1) were obtained by using SBA-15 as a hard-template, and CdLa2S4 nanoparticles were successfully grown on these mpg-C3N4 nanosheets via a facile hydrothermal method. The as-synthesized CdLa2S4/mpg-C3N4 hybrids were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microcopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, ultraviolet-visible diffuse reflection spectroscopy (DRS). Compared with pure CdLa2S4, the CdLa2S4/mpg-C3N4 hybrid materials displayed higher photocatalytic H2 evolution performance under the visible light (λ > 420 nm) using Na2S and Na2SO3 as the sacrificial agent. The optimal content of mpg-C3N4 was about 20 wt% and the corresponding photocatalytic H2 evolution was 5984.8 μmol h-1 g-1 (with an apparent quantum efficiency of 7.1% at 420 nm), which was 7.7 times higher than that of pure CdLa2S4. The results of photoluminescence (PL) and photocurrent response demonstrated that the recombination of photo-generated electron-hole pairs was effectively inhibited due to the well-matched band structure and intimate contact interfaces of CdLa2S4 and mpg-C3N4. Based on the results and analysis, a possible enhanced photocatalytic activity mechanism of CdLa2S4/mpg-C3N4 composites was also proposed.