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, Mo3S132– 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 Mo3S132–/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 gMOF–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 Mo3S132– 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 Mo3S132–/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.

Enhanced photocatalytic performance of a Ti-based metal-organic framework for hydrogen production: Hybridization with ZnCr-LDH nanosheets

“…Therefore, it remains an important challenge to improve the photocatalytic performance of NH 2 -MIL-125(Ti) photocatalysts. One of the viable strategies to enhance the photocatalytic activity of NH 2 -MIL-125(Ti) is to hybridize it with other semiconducting photocatalysts; such a hybridization can facilitate electron transfer between two components, and thus, the photocatalytic activity of the MOF can be enhanced 21,22 .…”

“…Of course, different composites of MOF/0D-semiconductors and/or MOF/2D-graphene as photocatalysts for water remediation have been reported in recent studies 23,24 . However, a few reports on hydrogen production via water photolysis using MOF-based hybrid composites have been reported 17–20,22 . Very recently, hybrid composites of MOFs and LDHs have been examined as gas and water adsorbents 25,26 .…”

Mixed-Phase MOF-Derived Titanium Dioxide for Photocatalytic Hydrogen Evolution: The Impact of the Templated Morphology

“…29 Among the Ti IV -based MOFs, the MIL-125 series consisting of functionalized (or not) ligands exhibit a 3dimensional and porous structure, and represent the most studied Ti IV -based MOFs for photocatalytic applications. [30][31][32] Recently, MIL-125-NH2 was utilized as a precursor for the synthesis TiO2 particles, decorated with either palladium or gold NPs for photocatalytic applications, such as CO2 reduction and hydrogen evolution. [33][34] The employment of expensive noble metal NPs as co-catalysts was necessary to enhance the otherwise inadequate photocatalytic performance of TiO2, due to high electron-hole recombination rates.…”

Two-Dimensional Materials and Composites as Potential Water Splitting Photocatalysts: A Review

“…The impact of this fusion is clearly evident from H 2 evolution rates whereby pure UiO-66 displayed no perceptible H 2 release, Pt/UiO-66 showed 3.9 µmol/g•h and adsorbed RhB/Pt/UiO-66 showed 116 µmol/g•h which is 30 times greater than un-treated Pt/UiO-66. A different photo-active MOF variant MIL-125-NH 2 for H 2 production from water can be used as the base material with a MoS integration, as discovered by Tu N. Nguyen, et al [190], to produce H 2 evolution rate as high as 2094 and 1454 µmol/g•h with quantum productivity 11% and 5.8% using two different kinds of MoS clusters; i.e., Mo 3 S 13 and IT-MoS respectively. MoS 2 is an inherently photo-active compound [191] and the sources of light responsive behavior are the vacancy defects and sulfur-edges only [192,193] while the basal faces do not contribute in catalysis and the size of particles is inversely related to the HER activity [194] Robust interaction between the supporting MOF and MoS result in higher exposed active area, lower electron conduction resistance and high stability.…”