Synergistic Enhancement of Hydrogen Production by ZIF-67 (Co) Derived Mo–Co–S Modified g-C₃N₄/rGO Photocatalyst

Abstract

A novel and high active g-C₃N₄/rGO/Mo–Co–S is successfully prepared by a simple hydrothermal reaction and calcination with nitrogen in a tube furnace. Using thioacetamide as the sulfur source, ZIF-67 (Co) as the cobalt source, and sodium molybdate as the molybdenum source, the Mo–Co–S co-catalyst is successfully prepared by high-temperature hydrothermal reaction and one-step sulfidation. The g-C₃N₄/rGO nanosheets and the new Mo–Co–S co-catalyst provide a large space for dye adsorption and also provide more reactive sites for the reaction. It exhibits synergistic effect between g-C₃N₄, rGO and Mo–Co–S on very high efficient photocatalytic hydrogen production. Under light irradiation, the EY dye acts as a photosensitizer, which broadens the visible light absorption range and absorption intensity of the semiconductor and forms an effective separation of the photogenerated charge. As an electron donor, TEOA can be oxidized by holes, thereby consuming holes and improving the efficiency of charge separation. The maximum amount of hydrogen evolution reaches about 589 μmol for 5 h over the g-C₃N₄/rGO/Mo–Co–S photocatalyst under visible light irradiation, which is 23.5 times higher than that of the pure g-C₃N₄. The high photocurrent response, the faster electron-transfer rate constant (Ket = 1.36 × 10⁹ s⁻¹), the short fluorescence lifetime (0.33 ns) and the small R_s (19.46 Ω) and R_et (59.67 Ω) together accelerated the efficient spatial charges transfer, thereby increasing the photocatalytic activity of H₂ production.

Graphical Abstract