Co-catalyst boosted photocatalytic hydrogen production driven by visible-light over g-C3N4: The synergistic effect between Ag and Ag2S

Abstract

Developing a co-catalyst structure with a rational design is necessary to improve the photocatalytic performance. In this work, a series of g-C3N4/Ag-Ag2S photocatalysts were prepared by depositing Ag nanoparticles onto g-C3N4 through photoreduction, followed by a partial sulfidation of Ag into Ag2S via a solution method. Various characterizations were employed to investigate the crystal phase, composition, and morphology of the synthesized samples in detail. The evaluation results for photocatalytic H2 production show that g-C3N4/Ag-Ag2S-8 possesses a H2 production rate of 223.5 μmol g−1 h−1 when subjected to a 300 W xenon lamp for 5 h, which far exceeds those of the remaining as-prepared samples. Besides, g-C3N4/Ag-Ag2S-8 also exhibits an acceptable photostability in recycling experiments. Based on multiple measurements on the textural properties, optical properties, charge separation performances, and proton reduction abilities of the as-prepared samples, it is believed that the rapid separation of photogenerated carriers and excellent proton capturing ability caused by the rationally designed Ag-Ag2S co-catalyst are the two key factors that can result in the efficient photocatalytic H2 production observed in g-C3N4/Ag-Ag2S. Furthermore, a plausible mechanism for the photocatalytic H2 production in g-C3N4/Ag-Ag2S is also provided. Thus, this work may provide new insights into the future development of semiconductor composites for photocatalysis.