Photochemical Hydrogen Production of Ta2O5 Nanotubes Decorated with NiO Nanoparticles by Modified Sputtering Deposition

The use of metal/oxide nanoparticles (NPs) as cocatalysts in heterogeneous photocatalysis is an important strategy to improve the photocatalytic activity of semiconductors for hydrogen generation. This article reports the use of a modified sputtering deposition method to prepare ultrafine NiO NPs cocatalysts dispersed on anodic Ta2O5 nanotubes (NTs). In situ X-ray absorption near-edge spectroscopy (XANES) measurements revealed that after exposing the as-prepared Ni NPs to air atmosphere a mixture of 68% of Ni and 32% of NiO was formed. Pure phase NiO NPs was successfully obtained after a controlled thermal oxidation at 500 °C which was confirmed by in situ XANES and ex situ XPS analyses. The photocatalytic hydrogen production activity was evaluated using ethanol as a sacrificial agent. Ta2O5 NTs with 0.16 wt % of NiO showed superior photocatalytic activity (up to 7.7 ± 0.3 mmol h–1 g–1) as compared to pure Ta2O5 NTs (4.9 ± 0.3 mmol h–1 g–1) The observed higher photocatalytic activity suggests that NiO/Ta2...