Abstract
Ascorbate acts as a reversible electron shuttle between tris(2-carboxyethyl) phosphine (TCEP) and ReI or RuII photosensitizers. Oxidized ascorbate is recycled up to 50 times by the TCEP → TCEP[double bond, length as m-dash]O redox process which enables 30 000 TONs per WRC in photocatalytic hydrogen production, thus exceeding the performance with pure ascorbate by far.