In this manuscript, the author reports a oxygen-vacancy-rich SrTiO3 prepared by a surface hydroxyl modification strategy for photocatalytic CO2 reduction. The as-prepared photocatalyst exhibited enhanced activity for photocatalytic CO2-to-CO conversion in comparision to prestine SrTiO3. The photocatalyst is well-characterized and the mechanism is well-elucited. I think the manuscript can be published in this journal after minor modifications.

1. The author used at least three terms to describe the photocatalyst, oxygen-rich vacancy SrTiO3, oxygen-rich defect SiTrO3, and oxygen-defect-rich STO. Do these terms all refer to the same photocatalyst? If yes, use the most accurate term throughout the manuscript.
2. “The improved dispersion of STO-OH-5 microspheres suggests an enhancement in long-range ordering, promoting a decrease in the internal energy of the crystalline structures. Furthermore, the small particle size is more favorable for the effective separation of photogenerated carrier, which facilitates the photocatalytic CO2 reduction reaction.” I don't think there's an absolute correlation between the efficiency of photogenerated charge separation and the size of the nanostructure. There is a bit of overexplained here.
3. "Abundant dislocations and deformations are found at the edges of the STO-OH-5 sample (yellow dashed circles), indicating the existence of defect-rich structures" ，I don't think that finding dislocations or deformations at the edge of the crystal means that the defects of the crystal have increased, and the author should do a rigorous comparison to come to the conclusion that the edge of the crystal is defective in the first place.
4. The solvent used in photocatalytic CO2 reduction should be stated in the manuscript. Did the system produce hydrogen? What is the CO selectivity of the system?
5. Some typos should be carefully modified. Such as 11422 (IR discussion) should be 1422 cm-1. I think the catalytic CO2 conversion process can be described more specifically, for example, the following references (ChemSusChem, 2019, 12, 4617-4622., ACS Applied Materials & Interfaces, 2022, 14, 29945-29955) are suggested to refer.