Efficient Light-Driven Hydrogen Evolution Using a Thiosemicarbazone-Nickel (II) Complex

Abstract

In the following work, we carried out a systematic study investigating the behavior of a thiosemicarbazone-nickel (II) complex ( NiTSC-OMe ) as a molecular catalyst for photo-induced hydrogen production. A comprehensive comparison regarding the combination of three different chromophores with this catalyst has been performed, using [ Ir(ppy) 2 (bpy)]PF 6 , [Ru(bpy) 3 ]Cl 2 and [ ZnTMePy]PCl 4 as photosensitizers. Thorough evaluation of the parameters affecting the hydrogen evolution experiments (i.e., concentration, pH, solvent nature, and ratio), has been performed in order to probe the most efficient photocatalytic system, which was comprised by NiTSC-OMe and [ Ir(ppy) 2 (bpy)]PF 6 as catalyst and chromophore, respectively. The electrochemical together with the photophysical investigation clarified the properties of this photocatalytic system and allowed us to propose a possible reaction mechanism for hydrogen production.

Photosensitizers for H2 Evolution Based on Charged or Neutral Zn and Sn Porphyrins

“…A number of molecular catalysts have shown remarkable efficiency toward photoinduced hydrogen production. The most noteworthy examples are noble metal-free molecular Co- or Ni-based systems, which are able to reduce protons efficiently. ,− Cobalt complexes with diglyoxime ligands (cobaloximes) are one well-documented class of catalysts for hydrogen evolution, , which are quite stable, can be readily synthesized using straightforward preparation methods and contain an inexpensive transition metal. , …”

Structurally modified T-metal complexes and organic dyes as photosensitizers and earth-abundant T-metal catalysts for photo-driven hydrogen evolution in artificial photosynthetic systems

“…Hence, hydrogen production in this system was initiated by reductive quenching of the excited photosensitizer by TEA. 84 Nickel(II) bis(diphosphine) complexes, known as 'DuBois' catalysts, are of topical interest for the HER as active photocatalysts. The protonation steps in the hydrogen evolution mechanism are assisted by the proton relay effect of the pendant amines, thus in turn reducing the overpotential of the proton reduction.…”

“…In this context, in 2019, Orio et al utilized a thiosemicarbazone Ni( ii ) complex (NiTSC-OMe, C30 , TSC-OMe = N , N ′-((1Z,1′Z)-(((2 E ,3 E )-butane-2,3-diylidene)bis(hydrazine-2,1-diylidene))bis((l1-sulfanyl)methanylylidene))bis(4-methoxyaniline)) as a molecular catalyst for photocatalytic hydrogen production. 84 Three different types of light-harvesting photosensitizers [Ir(ppy) 2 (bpy)]PF 6 , [Ru(bpy) 3 ]Cl 2 , and [ZnTMePy]PCl 4 (TMePy = 4,4′,4′′,4′′′-(porphyrin-5,10,15,20-tetrayl)tetrakis(1-methylpyridin-1-ium)) were tested along with the above Ni( ii ) catalyst. Several experiments were carried out using TEA or ascorbic acid (0.2 M) as the sacrificial electron donor in various pH buffer solutions (from pH = 2.5 to 10).…”

“…Hence, hydrogen production in this system was initiated by reductive quenching of the excited photosensitizer by TEA. 84…”

Nickel Complexes and Carbon Dots for Efficient Light‐Driven Hydrogen Production

“…Among these catalysts, we can distinguish Ni‐based complexes with thiosemicarbazone ligands [26–30] . These type of ligands have already been studied and proved to be redox‐active [31–39] . Furthermore, the presence of S‐ and N‐atoms in the ligand permits the protonation of the ligand and can serve as proton relays [40–42] .…”