The octahedral cage assembly [CoLCl(HO)]Cl has been synthesized in a single-step reaction by using a polypyridyl-functionalized tripodal silane ligand. The electrochemical behavior of the cage in water exhibits the pH dependence of potential as well as catalytic current indicating the possible involvement of proton-coupled electron transfer in H evolution. Electrocatalytic hydrogen evolution from an aqueous buffered solution gave a turnover frequency of 16 h. Further, this cage assembly has been explored as a photocatalyst (blue light irradiation λ 469 nm) for the evolution of H from water in the presence of Ru(bpy) as a photosensitizer and ascorbic acid as a sacrificial electron donor. This catalytic reaction is found to be pseudo first order with a turnover frequency of 20.50 h.

The development of cost-effective electrocatalyst with high activity and stability during the oxygen evolution reaction (OER) is a prerequisite for commercialization of several energy storage/generation technologies. Herein, porous carbon materials doped with Co, nitrogen, and sulfur were synthesized through the carbonization of a mixture containing [1-vinylimidazolium] [HSO4] ionic liquid (IL) and CoCl2 under an inert atmosphere. The structural diversity of ionic liquids offered control over the structure and properties of the carbon materials at the molecular level. The protic ionic liquid used acted as a soft template and a source of heteroatoms. A change in the mass ratio of cobalt chloride to ionic liquids resulted in materials with three different morphologies with/without S and N. The resulting Co10-NS-C material exhibited considerably enhanced catalytic performance toward the OER, which compared favorably to that of state-of-the-art Ru-based catalysts. Moreover, the Co10-NS-C catalyst demonstrated excellent stability up to 8 h without any decay in catalytic current.

A mononuclear ruthenium complex [Ru(tpy)(bpg)HO] bearing a bipyridine glycoluril where bpg = 4b,5,7,7a-tetrahydro-4b,7a-nepiminomethanoimino-6H-imidazo[4,5-f][1,10]phenanthro-line-6,13-dione acts as a robust water oxidation catalyst (WOC) at pH = 1 using Ce(iv) as a sacrificial oxidant. The turn over number (TON) for water oxidation is found to be ∼5 times higher than the parent complex [Ru(tpy)(bpy)HO] where tpy = 2,2':6',2''-terpyridine; bpy = 2,2'-bipyridine. The presence of intermolecular H-bonding groups and the electronic effect of the functionalized bipyridine ligand may play a significant role in water oxidation.

An efficient photochemical hydrogen evolution reaction in water supported by a 1D-coordination network of octahedral cages is demonstrated with high turnover numbers.

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