A Molecular Z‐Scheme Artificial Photosynthetic System Under the Bias‐Free Condition for CO 2 Reduction Coupled with Two‐electron Water Oxidation: Photocatalytic Production of CO/HCOOH and H 2 O 2

Bio‐inspired molecular‐engineered systems have been extensively investigated for the half‐reactions of H 2 O oxidation or CO 2 reduction with sacrificial electron donors/acceptors. However, there has yet to be reported a device for dye‐sensitized molecular photoanodes coupled with molecular photocathodes in an aqueous solution without the use of sacrificial reagents. Herein, we will report the integration of Sn IV ‐ or Al III ‐tetrapyridylporphyrin (SnTPyP or AlTPyP) decorated tin oxide particles (SnTPyP/SnO 2 or AlTPyP/SnO 2 ) photoanode with the dye‐sensitized molecular photocathode on nickel oxide particles containing [Ru(diimine) 3 ] 2+ as the light‐harvesting unit and [Ru(diimine)(CO) 2 Cl 2 ] as the catalyst unit covalently connected and fixed within poly‐pyrrole layer (RuCAT‐RuC 2 ‐ PolyPyr ‐PRu/NiO). The simultaneous irradiation of the two photoelectrodes with visible light resulted in H 2 O 2 on the anode and CO, HCOOH, and H 2 on the cathode with high Faradaic efficiencies in purely aqueous conditions without any applied bias is the first example of artificial photosynthesis with only two‐electron redox reactions.