Photocatalytic Hydrogen Generation System Using a Nickel-Thiolate Hexameric Cluster

Abstract

We report the use of a nickel-thiolate hexameric cluster, Ni6(SC2H4Ph)12, for photocatalytic hydrogen production from water. The nickel cluster was synthesized ex-situ and characterized by various techniques. Single crystal X-ray analysis, (1)H NMR, 2D COSY, ESI-MS, UV-visible spectroscopy, and TGA provided insight into the structure and confirmed the purity and stability of the cluster. Cyclic voltammetry helped confirm hydrogen evolution reaction (HER) activity of this catalyst. Photoreactions carried out using an iridium photosensitizer, Ir(F-mppy)2(dtbbpy)[PF6], and TEA as the sacrificial reductant revealed the high activity of the Ni6 cluster as a water reducing catalyst. High TONs (3750) and TOFs (970 h(-1)) were obtained at optimum catalyst concentration (0.025 mM), with low concentrations of catalyst yielding up to 30,000 turnovers. Quenching studies, along with the evidence obtained from the electrochemical analysis, showed that this water reduction system proceeds through a reductive quenching mechanism. Mercury poisoning studies confirmed that no active, metallic colloids were formed during the photocatalytic reaction.

Tiara-like Octanuclear Palladium(II) and Platinum(II) Thiolates and Their Inclusion Complexes with Dihalo- or Iodoalkanes

“…8 Thiolate-bridged polynuclear group 10 transition-metal complexes with chain structures, [M(-SR) 2 ] n (M = Ni, Pd), have been investigated in detail because they provide efficient catalysis of atom-economical organic reactions such as regioselective additions of thiols and disulfides across alkynes. [8][9][10][11][12][13] Tiara-like complexes, which are also polynuclear group 10 transition-metal thiolates and are characterized by toroidal architectures, have been studied extensively, both in terms of their intriguing structural features and with respect to the preparation of monodisperse metal sulfide nanoparticles, 14 non-linear optical materials, 15 photoactive water-reducing catalysts, [16][17] and host-guest chemistry. 15,[18][19][20][21] Tiara-like nickel complexes have received considerable attention resulting in the preparation of complexes with a variety of ring sizes [Ni(-SR) 2 ] n (n = [4][5][6][8][9][10][11][12].…”

“…15,[18][19][20][21] Tiara-like nickel complexes have received considerable attention resulting in the preparation of complexes with a variety of ring sizes [Ni(-SR) 2 ] n (n = [4][5][6][8][9][10][11][12]. 15,[17][18][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] In contrast, although several tiara-like hexanuclear palladium complexes have been reported, 9,14,19,[36][37][38][39][40][41][42][43] only one octanuclear complex, i.e., [Pd(-S n Pr) 2 ] 8 , is known, and was obtained as a mixture with hexanuclear [Pd(-S n Pr) 2 ] 6 . 19 For platinum, infinite thiolates and selenolates [Pt(-ER) 2 ] ∞ (E = S, Se) have been synthesized using a solvothermal method; …”

Synthesis and Properties Evolution of a Family of Tiara-like Phenylethanethiolated Palladium Nanoclusters

“…Of the various metal nanoclusters, tiara-like thiolated group 10 transition metal (Ni, Pd and Pt) clusters (denoted as [M(SR) 2 ] n ) not only show interesting structures, but also exhibit intriguing properties such as superior nonlinear optical property11, photocatalytic hydrogen generation property1213 and host-guest chemical property11141516. Their toroidal architectures are composed of a limited number of M(SR) 2 units with two doubly bridged thiolate ligands between each adjacent pair.…”

Editorial for the ACS Select Virtual Issue on Inorganic Chemistry Driving the Energy Sciences

“…49 The research group of Prof. Stefan Bernhard has diverged from these more common themes of investigation by interrogating the untested hexametallic nickel-(II) phenylethylthiolate cluster, Ni 6 (SC 2 H 4 Ph) 12 , as a molecular catalyst for the hydrogen evolution reaction (HER). 50 The cluster was shown to be an excellent HER catalyst when reduction was driven at an electrode or by a photoreductant. A particularly intriguing aspect of this study was the sensitivity of the structure to the ligand, thus affording a direct handle for tuning the structure and reactivity moving forward.…”