Electrocatalytic properties of [FeFe]-hydrogenases models and visible-light-driven hydrogen evolution efficiency promotion with porphyrin functionalized graphene nanocomposite

Synthesis, characterization, and electrochemistry of monophosphine‐containing diiron propane‐1,2‐dithiolate complexes related to the active site of [FeFe]‐hydrogenases

“…As shown in Figures , complexes 2 – 6 contain a butterfly diiron propane‐1,2‐dithiolate cluster ligated by five terminal carbonyls and a monophosphine ligand. The monophosphine ligands are located in an apical position of the distorted octahedral geometry of the attached iron atom, consistent with previously reported phosphine‐substituted analogs . The Fe1–Fe2 bond distances of complexes 2 – 6 [2.5035(7) Å for 2 , 2.5075(15) Å for 3 , 2.5012(10) Å for 4 , 2.5066(12) Å for 5 , and 2.5024(6) Å for 6 ] are analogous to tris(2‐methoxyphenyl)phosphine‐substituted diiron propane‐1,2‐dithiolate complex [2.5094(6) Å], but slightly shorter than that of the parent complex 1 [2.5196(7) Å] probably due to the effect of the monophosphine ligand.…”

“…On the basis of the aforementioned observations and the reported similar cases, we might propose the EECC (E = electrochemical; C = chemical) mechanism for H 2 production catalyzed by complexes 2 – 6 in the presence of HOAc. The proposed EECC catalytic mechanism for complex 2 as a representative is described as follows: the neutral compound 2 (denoted as [Fe I ‐Fe I ] 0 ) is first reduced at −1.93 V to form a monoanion [ 2 ] − ([Fe 0 ‐Fe I ] − , which is further reduced at −2.24 V to produce a dianion [ 2 ] 2 − ([Fe 0 ‐Fe 0 ] 2− ).…”

“…However, the second reduction peak currents of complexes 2 – 6 at about −2.24 V increased dramatically and linearly upon the consecutive addition of HOAc, wherein the current intensities ( i cat ) of the new reduction peaks have a linear correlation relative to the concentration ([HOAc]) of the added acid (insert in Figure ). Typically, such observations suggest an electrocatalytic process for the proton reduction to H 2 . That is to say, complexes 2 – 6 are active for the electrocatalytic H 2 production with weak acid HOAc.…”

Catalytic Metallopolymers from [2Fe‐2S] Clusters: Artificial Metalloenzymes for Hydrogen Production

“…The catalytic performance of these various polymer‐supported [2Fe‐2S] materials to date are summarized. While the immobilization of [2Fe‐2S] onto small‐molecule photosensitizers, semiconductor nanocrystals, nanocarbons, metal–organic frameworks (MOFs), and electrode surfaces have been reported, these supported systems are not covered in this review as the focus is on polymer‐based media.…”

Synthesis, structures, and electrocatalytic properties of phosphine‐monodentate, −chelate, and ‐bridge diiron 2,2‐dimethylpropanedithiolate complexes related to [FeFe]‐hydrogenases

“…−1.76, −2.12, and − 2.05 V increase rapidly upon sequential additions of TFA (0–10 mM) and have a linear correlation with TFA concentration ( insert in Figure ). This result suggests that a typical electrocatalytic process for proton reduction to H 2 takes place, that is to say, complexes 2a , 3a , and 4a are all found to be electrocatalytically active under TFA as a proton source. Additionally, relative to the monodentate 2a (Figure ‐I), the CV curves of the bidentate 3a and 4a (Figures ‐II and ‐III) display that a new reduction peak is found at E pc = ca.…”