## 4 Conclusions  
The presented work studies the processes of synthesis of structures of ZnO using atmospheric pressure microwave nitrogen plasma and investigates their photocatalytic activity in the processes of degradation of 2,4-dinitrophenol and the antibiotic ciprofloxacin when irradiated with sunlight.  
1. The work proposes an effective plasma method for formation of photosensitive ZnO powders. Zn microparticles were injected into the microwave plasma at a mass rate of 20 g/min;
2. Treatment of zinc metal powders using microwave nitrogen plasma has a number of advantages: a high gas temperature that promotes zinc evaporation and charging of microparticles by incoming fluxes of electrons and ions from the surrounding plasma that prevents the formation of agglomerates. Both of these factors contribute to the formation of ZnO structures ranging in size from hundreds of nanometers to several micrometers;
3. Study of the band gap parameters of ZnO structures using X-ray photoelectron spectroscopy demonstrates a high density of states near the Fermi level associated with defects contributing to the expansion of the photosensitivity range into the visible range;
4. High photoactivity was demonstrated (rate constants 0.036 min\({}^{-1}\) and 0.051 min\({}^{-1}\)) of synthesized ZnO structures during photodegradation of 2,4-dinitrophenol and ciprofloxacin, respectively, when exposed to solar radiation.  
Structures of ZnO synthesized using microwave plasma can find application in processes of mineralization of toxic organic compounds.  
In addition, ZnO microstructures can be utilized in scintillation detectors and phosphors, as well as being utilized as a binding component of strong composite materials.  
Conceptualization, A.M., S.A., A.U. and V.K. ([PERSON]); methodology, A.M., A.L. and M.G.; validation, A.M. and M.G.; formal analysis, V.K. ([PERSON]); investigation, S.A., A.U. and A.M.; resources, A.M., M.G., S.A., A.U. and V.K. ([PERSON]); writing, A.M.; writing--review and editing, A.M.; visualization, A.M.; supervision, A.M., M.G. and V.K. ([PERSON]); project administration, A.M. and V.K. ([PERSON]); funding acquisition, A.M. and V.K. ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
Figure 6: XPS spectra Zn2P\({}_{3/2}\) (**a**) and O1s (**b**).  
**Funding:** This research was performed in the frame of state assignments of the Ministry of Science and Higher Education of the Russian Federation for FSRC \"Crystallography and Photonics\" RAS (in part of structural studies of oxide powder), Federal State Budget Institution JJHT RAS (State Assignment No. 075-01129-23-00, in part of the development of plasma technologies), and within the Agreement with the Ministry of Science and Higher Education of the Russian Federation of 12.10.2021 N075-15-2021-1362 (in the part concerning the growth of ZnO microstructures as potential scintillation material).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
**Acknowledgments:** The authors are grateful to [PERSON]. [PERSON] (the Center for Physical and Physicochemical Methods of Analysis, Study of the Properties and Characteristics of Surfaces, Nanostructures, Materials and Products, UdmFRC Ural Branch of the Russian Academy of Sciences) for their help in the study of samples by the method of XPS.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.