Dye-Sensitized Photocathodes: Boosting Photoelectrochemical Performances with Polyoxometalate Electron Transfer Mediators

The amplification effect of polyoxometalates (POMs) on the efficiency of dye-sensitized nano-ITO cathodes is disclosed. The use of hybrid polyoxometalates of the type [PW11O39{SnC6H4≡C6H4F}]4–, F standing for a carboxylic group (POM-COOH) or a diazonium unit, allows control of the loading of the POMs on the electrode and investigation of key parameters. Even at very low loading, POM-COOH has a substantial effect on the photocurrent response with up to 25-fold increase. Besides ensuring the stability toward leaching, the anchoring function of the POM hybrids was also found to play an intricate role in the competition between the multiple events involved.