Distinctive organized molecular assemble of MoS2, MOF and Co3O4, for efficient dye-sensitized photocatalytic H2 evolution

Abstract

Stable and efficient photocatalyst has been a key research goal in recent years. Based on the dominant performances of MoS₂, metal organic frameworks (MOFs) and Co₃O₄ themselves, for example, MoS₂ has superior electronic properties, MOFs have a large specific surface area and Co₃O₄ has a suitable band gap to give a visible light response, and with a view to overcome the disadvantages of MoS₂, MOFs and Co₃O₄ individually, for example, the poor stability of MOFs, cobalt ions being easily released from Co₃O₄, a distinctive organized molecular assemble of MoS₂, MOF and Co₃O₄ was successfully designed and assembled with the shape of a leaf. Namely, the special structure of MoS₂–MOF appears as a leaf, and Co₃O₄ looks like the venation. More importantly, an efficient dye-sensitized photocatalytic H₂ evolution was obtained. For instance, when the content of Co₃O₄ was at 30%, the photocatalytic hydrogen production could reached up to 450.13 μmol in the EY-sensitized system under visible light irradiation within 5 hours. Moreover, the organized molecular assembled Co₃O₄ greatly improved the stability of the photocatalyst. Here, MoS₂ and a metal organic framework (MOF) were combined to form a new structure catalyst MoS₂–MOF, which provided a large specific surface area and sufficient active sites, the MoS₂ gave excellent electronic and optoelectronic properties and greatly improved the electron transport efficiency. The MoS₂–MOF/Co₃O₄ catalyst has a great fluorescence quenching rate, and the lifetime of the electron is also greatly improved. A peculiar synergetic effect of MoS₂ and Co₃O₄ on the MOF for photocatalytic hydrogen evolution is revealed and the synergy of MoS₂ and Co₃O₄ is the most critical factor. The above phenomena are supported by a series of characterization results such as SEM, XRD, TEM, EDX, XPS, BET, UV-vis DRS, FTIR, transient fluorescence and electro-chemistry, and so forth and the results of which were in good agreement with each other.