A noble metal-free photocatalytic system based on a novel cobalt tetrapyridyl catalyst for hydrogen production in fully aqueous medium

The new cobalt tetrapyridyl complex 1(BF4)(2) was characterized and assessed for hydrogen production in fully aqueous solution. Mechanistic information was gained thanks to a fast screening method, using chemical reductants and a Clark microelectrode. Optimal hydrogen production (443 TONs - 3 mL of H-2) was achieved under visible light-driven conditions, in the presence of a noble metal-free photosensitizer, the water soluble porphyrin 2Cl(4), and the ascorbate/tris-(2-carboxyethyl)phosphine (TCEP) sacrificial electron donor system.