Enhanced photocatalytic activity through anchoring and size effects of Au nanoparticles on niobate nanotubes and nanosheets for water splitting

The inorganic semiconducting potassium hexaniobate (K4Nb6O17) has a wide band gap of 3.4 eV and has been widely studied as a photocatalyst activated by the ultraviolet part of the solar spectrum. In this study, we have prepared nanotubes and nanosheets of H4Nb6O17 and attached Au nanoparticles of two different sizes to both. The resultant composites are characterised and their activity towards H2 generation by photocatalytic water splitting is investigated. We found that the morphology of the nano-niobate had minimal effect for the Au particles attached directly to the niobate, however for the (3-Aminopropyl) triethoxysilane (APTES) anchored Au particles a marked difference in their activities towards water splitting was observed. The APTES-Au-nanosheets produced a maximum volume of hydrogen of 1384.3 μmol g−1 h−1, which was much higher than the 36.9 μmol g−1 h−1 for the parent niobate nanotubes. Morphology and different interaction were considered as the main factors affecting photocatalytic efficiency.