The production of hydrogen gas using water as the molecular substrate currently represents one of the most challenging and appealing reaction schemes in the context of Artificial Photosynthesis (AP), i.e.,...

Molecular catalysts based on coordination complexes for the generation of hydrogen via photochemical water splitting exhibit a large versatility and tunability of the catalytic properties through chemical functionalization. In the present work, we report on light-driven hydrogen production in an aqueous solution using a series of cobalt polypyridine complexes as hydrogen evolving catalysts (HECs) in combination with CuInS2@ZnS quantum dots (QDs) as sensitizers, and ascorbate as the electron donor. A peculiar trend in activity has been observed depending on the substituents present on the polypyridine ligand. This trend markedly differs from that previously recorded using [Ru(bpy)3]2+ (where bpy = 2,2’-bipyridine) as the sensitizer and can be ascribed to different kinetically limiting pathways in the photochemical reaction (viz. protonation kinetics with the ruthenium chromophore, catalyst activation via electron transfer from the QDs in the present system). Hence, this work shows how the electronic effects on light-triggered molecular catalysis are not exclusive features of the catalyst unit but depend on the whole photochemical system.

Cobalt(II) complexes featuring hexadentate amino-pyridyl ligands have been recently discovered as highly active catalysts for the Hydrogen Evolution Reaction (HER), whose high performance arises from the possibility to assist proton...

Herein, we present the α-selective Giese reaction between pyranosyl/furanosyl bromides and dehydroalanine analogues, which provides access to a library of highly valuable α-C-glycosyl alanines. The key C-glycosyl radical is generated through photocatalysis by either the new generation copper(I) complex [(DPEPhos)(bcp)Cu]PF 6 or [Ru-(bpy) 3 ](BF 4 ) 2 . The reactions proceed smoothly, affording the desired α-C-glycosyl alanines in up to 99% yield when diethyl 1,4-dihydro-2,6dimethyl-3,5-pyridinedicarboxylate [Hantzsch ester (HE)] is used as an additive. N,N-Diisopropylethylamine (DIPEA) has been selected as a reductant in both protocols. A mechanistic study by means of transient absorption spectroscopy unveils a halogen-atom transfer (XAT) process in C-glycosyl radical formation.

The design of photocathodes for the hydrogen evolution reaction (HER), which suitably couple dye-sensitized p-type semiconductors and a hydrogen evolving catalyst (HEC), currently represents an important target in the quest for artificial photosynthesis. In the present manuscript, we report on a systematic evaluation of simple methods for the deposition of Pt metal onto dye-sensitized NiO electrodes. The standard P1 dye was taken as the chromophore of choice and two different NiO substrates were considered. Both potentiostatic and potentiodynamic procedures were evaluated either with or without the inclusion of an additional light bias. Photoelectrochemical characterization of the resulting electrodes in an aqueous solution at pH 4 showed that all the methods tested are effective to attain photocathodes for hydrogen production. The best performances (maximum photocurrent densities of −40 µA·cm−2, IPCE of 0.18%, and ⁓60% Faradaic yield) were achieved using appreciably fast, light-assisted deposition routes, which are associated with the growth of small Pt islands homogenously distributed on the sensitized NiO.