Fe4S4 Cubane Type Cluster Immobilized on a Graphene Support: A High Performance H2 Evolution Catalysis in Acidic Water

Abstract

The development of alternate catalysts that utilize non-precious metal based electrode materials such as the first row transition metal complexes is an important goal for economic fuel cell design. In this direction, a new Fe4S4 cubane type cluster, [PPh4]2[Fe4S4(DMET)4] (1) (DMET = cis-1,2-dicarbomethoxyethylene dithiolate) and its composite with functionalized graphene, (1@graphene) have been synthesized and characterized. The presence of nanocrystalline structures on graphene matrix in TEM and SEM images of 1@graphene indicate that the cluster (1) has been immobilized. The composite, 1@graphene evolves H2 gas from p-toluene sulfonic acid (TsOH) in a mixture of H2O and CH3CN under ambient conditions with a significant turnover number of 3200. 1@graphene electro-catalyzes H2 evolution at Ep, −1.2 V with remarkable throughput, catalytic efficiency and stability in only H2O or in only CH3CN. The Fe4S4 cluster (1) alone electro-catalyzes hydrogen evolution at Ep, −0.75 V from TsOH in CH3CN. The X-ray crystal structure of the Fe4S4 cluster (1) (λmax, CH2Cl2, 823 nm; ε, 2200 mol−1 cm−1) shows that it is dianionic with a cumulative oxidation state of +2.5 for the iron centers and short C-S bond distances (ca., 1.712 Å & 1.727 Å) indicating the presence of sulfur based radicals.

Graphene Supported Rhodium Nanoparticles for Enhanced Electrocatalytic Hydrogen Evolution Reaction

“…The functionalized graphene was obtained from graphitic powder by following a previously reported procedure 31 . Graphitic powder was sonicated in tetrahydrofuran ( thf ) for 1 h followed by centrifugation.…”

“…Our research focused towards the electrochemical hydrogen evolution resulted in a mononuclear iron(III) dithiolene of severely distorted square pyramidal geometry and a nickel(II)-sulfur based radical ligand complex that catalyze electrochemical hydrogen gas evolution at lower potentials in CH 3 CN. In these cases, along with metals, the dithiolene ligands are also potentially redox active forming sulfur based radicals 31–36 .…”

Iron Sulfide Materials: Catalysts for Electrochemical Hydrogen Evolution

“…To finish this section about iron sulfide-carbon hybrid catalysts, one example of a molecular iron sulfide compound immobilized on graphene shall be highlighted. Begum and co-workers report Fe 4 S 4 cubane clusters on graphene as high-performance H 2 evolution catalyst in acidic water [76]. , dimethylacetylene dicarboxylate, and lithium sulfide.…”

“…H-bonding interactions in [PPh4]2[Fe4(μ3-S)4(DMET)4]@graphene. Reprinted with permission from reference[76].…”

Enhanced Performance of Organic/Inorganic Hybrid Nanomaterials bearing Impregnated [PdL2] Complexes as Counter‐Electrode Catalyst for Dye‐Sensitized Solar Cells

“…Hybrid materials and immobilization systems have widespread use in the literature, and these are the most popular topics investigated by researchers such as catalyst chemistry, bio‐applications, drugs, energy, etc. Undoubtedly, immobilized systems are very attractive for the catalysis (reduction‐hydrogenation, oxidation, C‐C bond formation reactions etc.). Similar expressions can be said for materials or complexes containing palladium metal and the location of the palladium compounds is to particular importance in the catalyst chemistry .…”