WO/W:BiVO/BiVO graded photoabsorber electrode for enhanced photoelectrocatalytic solar light driven water oxidation.

We demonstrate the dual advantages of graded photoabsorbers in mesoporous metal oxide-based hetero interfacial photoanodes in improving photogenerated charge carrier (e/h) separation for the solar light-driven water-oxidation process. The pre-deposition of sol-gel-derived, tungsten-doped bismuth vanadate (W:BiVO) onto a primary BiVO water oxidation layer forms graded interfaces, which facilitate charge transfer from the primary photoabsorber to the charge transport layer, thereby superseding the thickness-controlled charge recombination at the BiVO water oxidation catalyst. As a result, the WO/BiVO hetero photoanode containing the photoactive W:BiVO interfacial layer showed 130% higher photocurrent than that of the interfacial layer-free hetero photoelectrode owing to the enhanced charge separation led water oxidation process.