The authors have clearly explained the effect of Mo doping on oxygen vacancy formation, anatase phase stability and photocatalytic activity of TiO2 via experimental and DFT based studies. Keeping in view the clarity of the paper, I strongly suggest this paper for publication after a minor revision. I have some suggestion and question as follows;
1. Why the authors prefer anatase to be more suitable material for device application instead of indirect band gap?
2. What were the initial lattice parameters applied to converge the 108 supercell?
3. Did the authors considered various hubbard U parameters to optimize these U values?
4. On line 13, the author talked about the formation energy but it is unclear formation energy of what, Oxygen or TiO2???
5. Kindly provide a comparison of Mo charge and Ti spin magnetization comparison with the existing literature.
6. On line 33, kindly explain the sentence “size is increased in some cases?”
7. For more clarity, it is required to tabulate the observed phonon modes with the existing literature for comparison.

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