Lignin as a quasi-homogenous electron mediator enables efficient photocatalytic H 2 evolution in molecular systems.

We report that the biomass-derived lignosulfonate (LS) can function as a quasi-homogenous electron mediator to efficiently promote the electron transfer from the excited erythrosin B (ErB) to the in situ generated Pt cocatalyst under visible light, thus enhancing the photocatalytic H 2 evolution activity by over 10 fold as compared to the LS-free system.