FeO Derived from an Iron-Containing Polyoxometalate Boosting the Photocatalytic Water Oxidation Activity of Ti-Doped TiO.

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(HO)(OH)(WO)(α-SbWO)] (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.