**4. Conclusions**

In summary, electron escaping conditions of various kinds of photocatalyst materials have been studied through photodeposition reactions. For photocatalyst nanomaterials, which show monodisperse crystal structure, Pt nanoparticles deposited randomly on the surface. This is attributed to the rich surface defects. In the heterostructured photocatalyst nanomaterials, Pt nanoparticles are preferred to load at one side. This is due to the electron migration driving force provided by heterojunction structure and work function difference. This is considered as a higher force, to promote the separation and migration of electrons, than the one caused by surface defects. Our results correspond well with known conclusions published previously. This is enough to demonstrate that photodeposition is usable for the study of electron escaping conditions. Further, it can be used as a "tool" to identify the catalytic ability of photocatalyst materials—especially the activity of their single particle.

**Author Contributions:** Conceptualization, C.Y. and Y.H.; methodology, C.Y.; formal analysis, C.Y. and Y.H.; writing—original draft preparation, C.Y.; writing—review and editing, Y.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Project of Shandong Province Higher Educational Science and Technology Program (No. J18KA073), the Doctoral Foundation of University of Jinan (No. XBS1643), the National Natural Science Foundation of China (grants nos. 52072150 and 51972146), and the China Association for Science and Technology (Young Elite Scientists Sponsorship Program).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** There are no conflict to declare.
