Intrinsic Photocatalysis of Morphology and Oxygen Vacancy‐Tunable Ultrathin WO 3 Nanosheets

The oxygen‐deficient WO 3 nanosheets (WO 3 NS) with pore structure were synthesized by a facile solvothermal approach and their microstructure and oxygen vacancy ( V o ) were regulated via heat treating atmosphere. The mean thickness of WO 3 NS is about 1.2 nm, which is equivalent to the thickness of single atom or molecule layer. The quantitative analyses on the ultrathin WO 3 NS of catalytic dynamic and V o concentrations have been done. The appropriate V o concentration can play a critical role in the transfer/separation of surface photogenerated carriers. Using phenol as the target compound and hydrogen peroxide as the accelerant, under visible‐light irradiation, the apparent rate constant of WO 3 ‐Ar NS is about 2.0 times and 1.8 times than that of WO 3 nanoparticles and WO 3 ‐air NS, respectively. These unique photocatalytic properties were attributed to the contribution of atomic layers, suitable crystal phase and porous surface and appropriate V o content, which increases the specific surface areas and regulates the electrical properties.