Fast fabrication of Ta2O5 nanotube arrays and their conversion to Ta3N5 for efficient solar driven water splitting

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, ~ 7.7 μm 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 VRHE and 12.9 mA cm −2 at 1.59 VRHE and after Ba-doping a value of 7.5 mA cm −2 at 1.23 VRHE is obtained.