Photoelectrochemical study of Ta3N5 nanotubes for water splitting

Abstract

Nanotubes (NTs) of Ta3N5 were synthesized by nitridation of Ta2O5 NTs. The samples were studied by scanning electron microscopy, UV-VIS spectrophotometry, x-ray diffraction and photoelectrochemical (PEC) measurements carried out in aqueous solutions of Na2SO4 and Fe(CN)6 3-/4-. The results show the presence of trapping states on illuminated pristine Ta3N5 NTs in Na2SO4 (aq). These trapping states act as recombination center for photogenerated holes, affecting the photocatalytic performance of Ta3N5 NTs. On the other hand, by using Fe(CN)6 3-/4- (aq) the photogenerated holes were scavenged efficiently without giving rise to the trapping states at Ta3N5 NTs/solution interface. The results obtained by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy have shown that the presence of these trapping states is a limiting step for water oxidation using pristine Ta3N5 NTs.