Confining Mo-activated CoS_x active sites within MCM-41 for highly efficient dye-sensitized photocatalytic H₂...

Although transition-metal-based sulfides have been identified as efficient catalysts to replace expensive noble metal catalysts for photocatalytic H₂ evolution reaction (HER), their activities are still unsatisfied and could be further improved by controlling their microstructures and electronic structures. Herein, we present an effective strategy to confine highly active Mo-activated CoS_x (Mo-CoS_x) active sites within MCM-41 frameworks by sulfurization of Co-doped MCM-41 during the in situ photoreduction of [MoS₄]^2- in Erythrosin B-triethanolamine (ErB-TEOA) system. It is found that Co-MCM-41 offers not only abundant coordinatively unsaturated Co sites to be activated by Mo and S but also large surface area to effectively disperse the in situ generated amorphous Mo-CoS_x active sites. Under 520 nm irradiation, the most efficient Mo-CoS_x/MCM-41-100 (Si/Co = 100) catalyst exhibits ~7, 3, and 4 times higher H₂ evolution activity than free MoS_x, free Mo-CoS_x, and CoS_x/MCM-41-100, respectively, and an apparent quantum yield (AQY) of 12.3% for H₂ evolution. Furthermore, when Mo-CoS_x/MCM-41-100 was sensitized with a more stable fluorescein (FL) dye, the photocatalytic system shows a sustainable H₂ evolution activity in a 20 h reaction, showing the good stability of Mo-CoS_x/MCM-41-100 catalyst. This work provides a new insight into the design and development of highly active hybrid H₂ evolution catalysts based on transition metals for highly efficient and large-scale solar energy conversion to clean H₂ energy.