Ascorbate as an electron relay between an irreversible electron donor and Ru(II) or Re(I) photosensitizers

Ascorbate acts as a reversible electron shuttle between tris(2-carboxyethyl) phosphine (TCEP) and Re-I or Ru-II photosensitizers. Oxidized ascorbate is recycled up to 50 times by the TCEP -> TCEP=O redox process which enables 30 000 TONs per WRC in photocatalytic hydrogen production, thus exceeding the performance with pure ascorbate by far.