## 3 Results
Such absorptions were not observed for the deposited CBXH\({}_{2}\) (Figure 5A(b)), which exhibited enhanced absorption at 1716 cm\({}^{-1}\) due to stretching of the protonated COOH ligand [38]. The peaks at 1647 cm\({}^{-1}\) (Figure 5A(a)) and 1650 cm\({}^{-1}\) (Figure 5A(b)) resulted from C=C stretching [39]. Carbon dots (Figure 5A(c)) showed absorptions at 1457 cm\({}^{-1}\), attributed to stretching of a C-C type. The minimum, at 1368 cm\({}^{-1}\), was observed due to bending of surface C-OH groups [39]. Similar peaks were recorded for the films formed from carbon dot suspensions (Figure 5A(d)). EPD of PTFE was performed from suspension of PTFE particles, which were dispersed and charged using CBX\({}^{2-}\). Figure 5B(a) shows FTIR data for PTFE, which exhibits absorptions at 1149 and 1203 cm\({}^{-1}\). According to the literature, C-C and C-F\({}_{2}\) asymmetric vibrating contribute to absorption at 1149 cm\({}^{-1}\), whereas the minimum at 1203 cm\({}^{-1}\) was due to symmetric vibrating of C-F\({}_{2}\)[40]. The FTIR spectra of deposits prepared from CBXNa\({}_{2}\) solutions (Figure 5B(b,c) containing PTFE showed similar peaks, and confirm the deposition of PTFE. The higher polymer content in the suspension led to the enlarged polymer content in the film. The electron microscopy imaging data (Figure 6) for the composite deposit formed by EPD from 10 gL\({}^{-1}\) PTFE suspension contained larger number of the PTFE particles, compared to the film formed from the 5 gL\({}^{-1}\) PTFE bath. The SEM analysis revealed the formation of continuous deposits. The SEM images for the films prepared from 10 gL\({}^{-1}\) PTFE suspension showed reduced porosity and relatively dense packing of the submicrometre PTFE particles. Annealing led to the burning out of the CBXH\({}_{2}\) phase and melting of the PTFE particles, which resulted in reduced porosity. The films prepared from 5 gL\({}^{-1}\) PTFE suspension were porous (Figure 6) due to low PTFE content. The increase in the PTFE content in the films resulted in reduced porosity, as indicated by the electron microscopy images of films formed from 10 gL\({}^{-1}\) PTFE suspensions (Figure 6). Such films were analyzed by potentiodynamic and EIS studies in the 3% NaCl solutions. Figure 5: FTIR testing data for (**A**) (a) original CBXNa\({}_{2}\), (b) film material, formed from 1 gL\({}^{-1}\) CBXNa\({}_{2}\) in water at 15 V, (c) carbon dots, (d) deposit formed from 0.5 gL\({}^{-1}\) CBXNa\({}_{2}\) with 0.5 gL\({}^{-1}\) carbon dots in water at 15 V; (**B**) (a) PTFE (b,c) deposits, obtained from 1 gL\({}^{-1}\) CBXNa\({}_{2}\) with (b) 0.5 gL\({}^{-1}\) and (c) 1 gL\({}^{-1}\) PTFE in ethanol-water solvent at 50 V.  
The data from electrochemical testing presented in Figure 7 demonstrate that films of the PTFE polymer allowed for corrosion protection. The Tafel graphs show that coating deposition resulted in a lower current for the anodic part of the graph, with an enlarged corrosion potential. The analysis of the Tafel plots showed corrosion currents of 0.01 and 2.6 \(\mu\)Acm\({}^{-2}\) for coated and uncoated substrates, respectively. The EIS data presented in the Nyquist plot were analyzed using an equivalent circuit (Figure 7), similar to that described in [41], where R\({}_{\rm s}\), R\({}_{\rm pore}\) and R\({}_{\rm ct}\) are solution resistance, resistance of electrolyte in pores and charge transfer resistance, respectively. C\({}_{1}\) represents capacitance of the film and C\({}_{2}\) is a double layer capacitance at the substrate surface in pores. The modeling results correlated with the experimental data. Figure 6: SEM data for films (**A**,**B**) before and (**C**,**D**) after annealing (1 h at 350 \({}^{\circ}\)C), for films prepared using 1 gL\({}^{-1}\) CBXNa\({}_{2}\) with (**A**,**C**) 5 gL\({}^{-1}\) PTFE and (**B**,**D**) 10 gL\({}^{-1}\) PTFE in ethanol-water solvent at 50 V.  
Figure 7: (**A**) Tafel plot, (**B**) Nyquist plot for substrate (a) without and (b) with coating; inset shows equivalent circuit.