Organic Sensitizers for Photoanode Water Splitting in Dye-Sensitized Photoelectrochemical Cells

Metal-free di-branched organic sensitizers, containing different heteroaromatic (phenothiazine, phenoxazine and carbazole) donor moieties, have been investigated as photoactive anode sensitizers in the photoelectrochemical generation of oxygen and water splitting. Photoelectrochemical properties have been studied both in the presence of a sacrificial electron donor, to closely evaluate the charge-transfer phenomena and the external quantum efficiency, and with a common water oxidation catalyst, to preliminarily assess the photoelectrochemical water-splitting activity and oxygen production. The experimental performance trend, in terms of photogenerated charge and evolved gas, was phenothiazine>carbazole>phenoxazine, arising from superior light-harvesting capability and more efficient electron injection to the semiconductor.