Dye-sensitized photoelectrochemical water oxidation through a buried junction

Significance Artificial photosynthetic systems use molecular light absorbers to convert sunlight into useful chemical fuels such as hydrogen, methanol, or ammonia. A key bottleneck in these systems is the oxidation of water to produce O 2 . This anodic reaction occurs under strongly oxidizing conditions that result in damage to organic dyes, electron relays, and catalyst molecules. Here we show that encapsulation of the molecular components of a solid-state dye-sensitized solar cell by a 2-nm-thick coating of TiO 2 dramatically improves cell stability under water-splitting conditions. The physical separation of the dye from the solution in which the water-splitting reaction takes place enables the use of dyes that efficiently absorb in the visible and allows optimization of the pH of catalytic water oxidation.