## 3 Results
### ZnO Powder Characterization  
According to electron microscopy data (Figure 2a), a morphologically heterogeneous crystalline precipitate is formed during synthesis. Among the individual elements of the precipitate, tetrapods, or hexagonal rods, can be observed. The structures range in size from hundreds of nanometers to a few micrometers. According to EDX (Table 1), the composition of the ZnO powder contained, in addition to the main components of zinc and oxygen, an atomic fraction of nitrogen of the order of 4%, which confirms the nitridization of the precipitate. The observed excess oxygen content is associated with water vapors and oxygen absorbed by the surface of ZnO structures as well as contained in the pores of ZnO powder. Diffraction reflections on the X-ray diffraction spectrum of oxidized zinc microstructures correspond to the hexagonal wurtzite structure of ZnO (JCPDS no. 05-0664). The most intense reflections are observed at 31.68 \({}^{\circ}\), 34.35 \({}^{\circ}\), and 36.16 \({}^{\circ}\), corresponding to reflections from planes (100), (002), and (101) ZnO. The lattice parameter d is determined from the Bragg-Wulff equation:  
\[2d*\sin\left(\theta\right)=\lambda, \tag{1}\]  
where \(\theta\) is the diffraction angle and \(\lambda\) is the wavelength of the utilized radiation. The sizes of coherent scattering regions (CSRs) in the samples under study were estimated using the Debye-Scherrer formula:  
\[D=\frac{k\cdot\lambda}{\beta\cdot\cos\ \theta^{\prime}} \tag{2}\]  
where \(D\) is the average size of CSRs, which can be less than or equal to the grain size; \(k\) is the dimensionless particle shape coefficient (Scherrer constant); \(\lambda\) is the wavelength of copper X-ray radiation; \(\beta\) is the width of the reflection at half maximum; and \(\theta\) is the diffraction angle. The lattice parameters of ZnO powder are characteristic of a hexagonal unit with \begin{table}
\begin{tabular}{c c c c} \hline
**Element** & **Zn** & **O** & **N** \\ \hline Quantity \% & 27.56 & 68.32 & 4.12 \\ \hline \end{tabular}
\end{table} 
Table 1: Concentrations (in %) of the main components of ZnO powder before photocatalysis according to EDX data. a = 3.258 A and c = 5.21 A, volume 47.95 A\({}^{3}\). The a and c values are higher than that of ZnO standard (JCPDS card no. 05-0664): a = 3.249 A and c = 5.205 A, volume 47.58 A\({}^{3}\). The sizes of the crystallites 48 nm were estimated from formula (2). Displacement may be due to an increase in the lattice parameter ZnO due to partial substitution of oxygen with nitrogen. Since the radius of nitrogen (1.46 A) is greater than oxygen (1.38 A), replacing oxygen with nitrogen in the ZnO lattice can cause it to deform. A similar effect was observed in [21]. According to XPS date (calculation was conducted for the spectra of Zn2p, O1s, and C1s), we calculated the concentrations of the main components of the powders (Table 2). It can be seen that the powder composition according to XPS was different from that obtained according to EDX (Table 1). The Zn-to-O atomic ratio, in this case, is closer to the stoichiometric value, however, there is an excess of zinc. For qualitative XPS analysis, the surface of the samples is previously etched, which results in surface cleaning. The excess of zinc found in the measurements is associated with a feature of the thermodynamically stable wurtzite phase of ZnO, in which oxygen vacancies and interstitial zinc are always present. These types of defects determine the electronic conductivity type ZnO. The presence of carbon (peak 285 eV corresponding to the C-O bond) is associated with hydrocarbon contamination of the surface, which is  
Figure 2: SEM images (**a**) and X-ray diffraction pattern (**b**) of ZnO powder. Scale bar: 10 \(\upmu\)m.  
difficult to remove. Of particular note is the absence of nitrogen in the surface layer, which was previously evident in the EDX data. The melting and evaporation temperatures of zinc are 419.5 \({}^{\circ}\)C and 907 \({}^{\circ}\)C, respectively.