Abstract
In the present work we grow anodic self-organized Ta2O5 nanotube layers, which are converted by ammonolysis to Ta3N5 nanotubes, and then are used as photoanodes for photoanalytic water splitting. We introduce a two-step anodization process that not only improves order (reduced growth defects) and overall light absorption in the nanotube layers, but also provides a significantly reduced interface charge resistance at the nitride/metal interface due to subnitride (TaNx) formation. As a result, such nanotube anodes afford a 15-fold increase of the photocurrent compared with conventional nanotubular Ta3N5 electrodes under AM 1.5G simulated sunlight (100 mW cm(-2)) conditions.