This manuscript concludes the DFT calculation and experimental study to analyze the effect of Mo doping on TiO2. The authors have repeatedly emphasized oxygen vacancies in their titles, abstractions, and conclusions, but the evidence and discussion for this is actually weak. In addition, the manuscript also has the following problems. Therefore, I think the authors should make a comprehensive revision and provide new evidence to support their main conclusion.

1. The first and second paragraphs of introduction should be shortened.
2. What I can't understand is why the authors cited many reference for a simple, well-known idea. For example: “…cleaning coatings using solar light (1-11).”; the references for the first three paragraphs are over 50. The total number of references is close to 100.
3. Now that a lot of relevant research has been published, how is their work different and innovative? This must be made clear at the end of the introduction.
4. In Figure 1, how did the authors construct the model of Mo + oxygen vacancy in TiO to ensure it has the lowest energy? This point should be clearly expressed.
5. Under normal conditions, 750 degree annealing will cause phase transition of most TiO2.Why does only 33% of the phase transitions occur in this work?
6. How does the Mo doping can produce oxygen vacancy? For the point, the authors should provide more experimental evidence and further discuss them.
7. The information of many references are incomplete, please check carefully and supplement.

Although the authors' revision is not completely satisfactory, I think it can be published now.