FeO x Derived from an Iron-Containing Polyoxometalate Boosting the Photocatalytic Water Oxidation Activity of Ti 3+ -Doped TiO 2

The development of efficient and stable catalyst systems using low-cost, abundant, and nontoxic materials is the primary demand for photocatalytic water oxidation. Distinguishing the true active species in a heterogeneous catalytic system is important for construction of efficient catalytic systems. Herein, hydrothermally synthesized Ti self-doped TiO , labeled as Ti /TiO , was first used as a light absorber in a powder visible light-driven photocatalytic water oxidation reaction. When an iron-containing polyoxometalate Na [Fe (H O) (OH) (W O ) (α-SbW O ) ] (Fe11) was used as a cocatalyst, an amorphous layer of active species was wrapped outside the initial Ti /TiO nanorod and the in situ formed composite was labeled as F/Ti /TiO . When the composite F/Ti /TiO was tested as a photocatalytic water oxidation catalyst, dramatically improved oxygen evolution performance was achieved. The composite F/Ti /TiO showed an oxygen evolution rate of 410 μmol/g/h, which was about 11-fold higher than that of prism Ti /TiO . After 24 h of illumination, an O yield of 36.4% was achieved. The contrast experiments, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy characterization demonstrated that FeO is the true cocatalyst that enhanced the oxygen evolution activity of TiO . A recycling experiment proved that the composite F/Ti /TiO has favorable stability in the oxygen production process.