Abstract
This work shows that highly ordered and mechanically stable micrometer-long Ta2O5 nanotube arrays can be fabricated by galvanostatic anodization in a few seconds. Typically, similar to 7.7 mu m long nanotubes can be grown at 1.2 A cm(-2) in only 2 s. Such nanotubes can be converted to Ta3N5 nanotube arrays by nitridation. Photoelectrochemical (PEC) water splitting using AM 1.5G illumination yields for the Ta3N5 nanotube photoanode modified with cobalt phosphate (Co-Pi) remarkable photocurrents of 5.9 mA cm(-2) at 1.23 V-RHE and 12.9 mA cm(-2) at 1.59 V-RHE and after Ba-doping a value of 7.5 mA cm(-2) at 123 V-RHE is obtained. (C) 2014 Elsevier B.V. All rights reserved.