Detailed investigations of a photocatalytic system capable of producing hydrogen under pre-catalytic aerobic conditions are reported. This system consists of the NHC precursor chromophore [Ru(tbbpy)2 (RR'ip)][PF6 ]3 (abbreviated as Ru(RR'ip)[PF6 ]3 ; tbbpy=4,4'-di-tert-butyl-2,2'-bipyridine, RR'ip=1,3-disubstituted-1H-imidazo[4,5-f][1,10]phenanthrolinium), the reduction catalyst Co(dmgH)2 (dmgH=dimethylglyoximato), and the electron donor ascorbic acid (AA). Screening studies with respect to solvent, cobaloxime catalyst, electron donor, pH, and concentrations of the individual components yielded optimized photocatalytic conditions. The system shows high activity based on Ru, with turnover numbers up to 2000 under oxygen-free and pre-catalytic aerobic conditions. The turnover frequency in the latter case was even higher than that for the oxygen-free catalyst system. The Ru complexes show high photostability and their first excited state is primarily located on the RR'ip ligand. X-ray crystallographic analysis of the rigid cyclophane-type ligand dd(ip)2 (Br)2 (dd(ip)2 =1,1',3,3'-bis(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)bis(1H-imidazo[4,5-f][1,10]phenanthrolinium)) and the catalytic activity of its Ru complex [{(tbbpy)2 Ru}2 (μ-dd(ip)2 )][PF6 ]6 (abbreviated as Ru2 (dd(ip)2 )[PF6 ]6 ) suggest an intermolecular catalytic cycle.

Mg‐based batteries, which use the Mg2+ shuttle, theoretically offer several advantages compared to the Li technology, such as higher theoretical volumetric capacity (3833 mA h cm−3) of the Mg‐metal anode, the possibility to be safely handled in air, and dendrite‐free electrodeposition. In this study, vanadium oxychloride was employed as an electrode material in a Mg‐based battery. As the cell delivered just 45 mA h g−1 in the first cycle, we tried to improve the delivered capacity through preliminary cycling of the VOCl electrode with Li. The strategy is based on the ability of VOCl to expand its interlayer spacing upon intercalation of ions or molecules within them. In fact, a VOCl electrode with expanded interlayer spacing should facilitate the intercalation of Mg2+, thus leading to higher specific capacities. The Li pretreatment was able to promote the specific capacity by a factor of four (170 mA h g−1) after the first discharge at 298 K. Over 130 mA h g−1 was retained at 5 mA g−1 after 70 cycles. Structural and electrochemical characterization was carried out by means of galvanostatic charge/discharge tests, cyclic voltammetry, ex situ X‐ray photoelectron spectroscopy, X‐ray diffraction, transmission electron microscopy coupled with energy‐dispersive X‐ray spectroscopy, and electron energy loss spectroscopy. Inductively coupled plasma optical emission spectrometry was used to determine the concentration of lithium in the electrode.