Black Nb⁴⁺ self-doped K₄Nb₆O₁₇ microspheres were prepared for the first time through a facile UV light photoreduction method. By the introduction of Nb⁴⁺, the defective K₄Nb₆O₁₇ can harvest the full spectrum of visible light as well as near-infrared light. The black K₄Nb₆O₁₇microspheres showed improved visible-light-driven photocatalytic H₂ production activity. Importantly, the present synthetic approach is also applicable to the preparation of other Nb⁴⁺self-doped niobates. 

Chem. Commun., 2014,50, 9554-9556