Photochemical water splitting mediated by a C1 shuttle

Abstract

The possibility of performing photochemical water splitting in a two-stage system, separately releasing the H₂ and O₂ components, has been probed with two separate catalysts and in combination with a formaldehyde/formate shuttling redox couple. In the first stage, formaldehyde releases hydrogen vigorously in the presence of an Na₄[Fe(CN)₆]·10H₂O catalyst, selectively affording the formate anion. In the second stage, the formate anion is hydro-genated back to formaldehyde by water and in the presence of a Bi₂WO₆ photocatalyst whilst releasing oxygen. Both stages operate at room temperature and under visible light irradiation. The two separate photocatalysts are compatible since water splitting can also be obtained in one-pot experiments with simultaneous H₂/O₂ evolution.