Facile preparation of porous g-C3N4/MoS2 heterojunction for hydrogen production under simulated sunlight

Abstract

The limited surface areas and the high recombination rate of photogenerated carriers have always been two sticky problems of graphite-like carbon nitride (g-C3N4) for the application of solar hydrogen production. In this article, the porous g-C3N4 was prepared by the improved thermal polymerization method to enlarge its specific surface areas and to facilitate the transfer of internal electric charges. Then, heterojunction formed by MoS2 deposited on the g-C3N4 was built to extend the recombination time of photoproduction electrons and holes. Several techniques were used to research their structures as well as the physical and chemistry properties, such as the specific surface area analysis (BET), Fourier transform infrared spectroscopy, UV–vis diffuse reflectance spectra, transmission electron microscopy, X-ray photoelectron spectroscopy, and so on. Finally, their performance of photocatalytic hydrogen evolution was studied under simulated sunlight irradiation. As a result, the optimal ratio of melamine to urea is 1:3 for preparing the porous g-C3N4, and the g-C3N4/MoS2 has a high efficiency of photocatalytic hydrogen evolution, ca. 1913 μmol·g–1·h–1. The results showed that the composites had higher hydrogen evolution than the pure ones, which the activity increasing first, then decreasing as the contents of MoS2 growing in quantity. Furthermore, the synergy effects are elaborated by electrochemical impedance spectroscopy and Mott-Schottky analyses.