Photocatalytic Hydrogen Generation from a Visible-Light-Responsive Metal–Organic Framework System: Stability versus Activity of Molybdenum Sulfide Cocatalysts

Abstract

We report the use of two earth abundant molybdenum sulfide-based cocatalysts, Mo₃S₁₃^2- clusters and 1T-MoS₂ nanoparticles (NPs), in combination with the visible-light active metal-organic framework (MOF) MIL-125-NH₂ for the photocatalytic generation of hydrogen (H₂) from water splitting. Upon irradiation (λ ≥ 420 nm), the best-performing mixtures of Mo₃S₁₃^2-/MIL-125-NH₂ and 1T-MoS₂/MIL-125-NH₂ exhibit high catalytic activity, producing H₂ with evolution rates of 2094 and 1454 μmol h^-1 g_MOF^-1 and apparent quantum yields of 11.0 and 5.8% at 450 nm, respectively, which are among the highest values reported to date for visible-light-driven photocatalysis with MOFs. The high performance of Mo₃S₁₃^2- can be attributed to the good contact between these clusters and the MOF and the large number of catalytically active sites, while the high activity of 1T-MoS₂ NPs is due to their high electrical conductivity leading to fast electron transfer processes. Recycling experiments revealed that although the Mo₃S₁₃^2-/MIL-125-NH₂ slowly loses its activity, the 1T-MoS₂/MIL-125-NH₂ retains its activity for at least 72 h. This work indicates that earth-abundant compounds can be stable and highly catalytically active for photocatalytic water splitting, and should be considered as promising cocatalysts with new MOFs besides the traditional noble metal NPs.