Design of multi-layered TiO2–Fe2O3 photoanodes for photoelectrochemical water splitting: patterning effects on photocurrent density

We report the effect of patterning on photoelectrochemical (PEC) water-splitting performance. Oxide–oxide heterostructures based on horizontal and vertical heterojunctions were fabricated on transparent conductive oxide glass by sequential plasma enhanced chemical vapor deposition (PECVD) of individual metal oxide. Featured masks were employed to enable three-dimensional patternings of stripes and cross-bars structures formed by Fe 2 O 3 and TiO 2 layers. PEC measurement was carried out by a three-electrode cell. It was found that double layered TiO 2 //Fe 2 O 3 :FTO showed a decrease in PEC performance when compared with single Fe 2 O 3 :FTO layer, whereas triple-layered Fe 2 O 3 //TiO 2 //Fe 2 O 3 :FTO (both patterned and unpatterned samples) displayed enhanced photocurrent density. The results show that the existence of multiple phase boundaries does not always add up to PEC enhancement observed in single heterojunction.