Effects of Distortion of Metal–Oxygen Octahedra on Photocatalytic Water‐Splitting Performance of RuO 2 ‐Loaded Niobium and Tantalum Phosphate Bronzes

Sodium, niobium, and tantalum phosphate bronzes Na 4 M 8 P 4 O 32 (M=Nb, Ta) are employed as photocatalysts for water splitting to reveal the effects of the distortion of metal–oxygen octahedra on the photocatalytic performance. Addition of RuO 2 as a co‐catalyst leads to high, stable activity in the stoichiometric production of H 2 and O 2 under UV irradiation. The combination of highly crystallized phosphates and a high dispersion of RuO 2 particles result in high photocatalytic activity. The sodium niobium phosphate bronze Na 2 Nb 8 P 4 O 32 , consisting of a framework built up from slabs of corner‐sharing NbO 6 octahedra connected through isolated PO 4 tetrahedra, provide heavily distorted NbO 6 octahedra with large internal dipole moments. The results support the existing view that the activity correlates with the magnitude of the dipole moment. The heavy distortion of NbO 6 octahedra is shown to play a significant role in photocatalytic water splitting.