Tantalum nitride nanotube photoanodes: Establishing a beneficial back-contact by lift-off and transfer to titanium nitride layer

In this work we introduce the use of TiN/Ti2N layers as a back contact for Ta3N5 membranes of lifted-off anodic Ta3N5 nanotubular layers. In photoelectrochemical H2 generation experiments under simulated AM 1.5G light, a shift in the onset potential of anodic photocurrents to lower potentials is observed, as well as a higher magnitude of the photocurrents compared to a conventional Ta3N5 nanotubular layer (Ta3N5/Ta, ~ 0.5 VRHE). We ascribe this beneficial effect to the improved conductive properties of the TiNx-based back contact layer that enables a facilitated electron transport from the tantalum nitride based materials to the conductive substrate.