## 2 Materials and Methods
### Characterization  
Using an energy dispersive spectrometer (EDS, Quantax 200, Bruker, Billerica, MA, USA) attached to a scanning electron microscope (SEM, LYRA I XMU, Tescan, Brno, Czechia), the surface morphology and composition were investigated. Using Ni-filtered CuK\({}_{\alpha}\) radiation (\(\lambda\) = 0.154178 nm) and a symmetrical Bragg-Brentano mode, the phase composition was examined utilizing X-ray diffraction (XRD, URD-6 Seiferd & Co., Antweiler, Germany) across a 26 range of 20-80\({}^{\circ}\) in a step of 0.1\({}^{\circ}\). Every step had a scanning rate of 6 s.  
Through relations (1) and (2), the weight fractions of the rutile and anatase were determined following Ref. [24]. \[\mathrm{W_{rutile}}=\mathrm{I_{r}}/(\mathrm{K}\mathrm{I_{a}}+\mathrm{I_{r}}) \tag{1}\]  
\[\mathrm{W_{anatase}}=\mathrm{K}\mathrm{I_{a}}/(\mathrm{I_{r}}+\mathrm{K} \mathrm{I_{a}}) \tag{2}\]  
where \(\mathrm{W_{rutile}}\) and \(\mathrm{W_{anatase}}\) are the weight fractions of rutile and anatase, respectively; \(\mathrm{I_{r}}\) and \(\mathrm{I_{a}}\) are the experimentally determined intensities of the diffraction peaks corresponding to the rutile and anatase phases; and K denotes a coefficient that is equal to 0.886 in formulas (1) and (2). The Scherrer equation (Equation (3)) was utilized to compute the sizes of the crystallites (D) as coherent reflective domains [25]. \[\mathrm{D}=\frac{\mathrm{K}\lambda}{\beta_{\mathrm{D}}\mathrm{cos}\theta} \tag{3}\]  
In this equation, the shape constant (K = 0.9), wavelength (\(\lambda\)) of Cu K\({}_{\alpha}\) radiation, full width at half maximum (\(\beta_{\mathrm{D}}\)) of XRD peak (in radians), and diffraction angle (\(\theta\)) are represented, respectively. The microstrain (\(\varepsilon\)) and dislocation density (\(\delta\)) were calculated by using the following equations [26]:  
\[\varepsilon=\frac{\beta_{\mathrm{D}}}{4\mathrm{tan}\theta} \tag{4}\]  
\[\delta=\frac{1}{\mathrm{D}^{2}} \tag{5}\]  
The microhardness measurements with DuraScan 20 Lite (ZwickRoell GmbH Co. KG, Ulm, Germany) tester equipped with a Knoop indenter were conducted under load control mode, applying a peak force of 5 gf. Ten measurements were made on each polished and coated surface to gather statistical information and calculate the results' dispersion. A  
Figure 1: Images of the glow-discharge cleaning (**a**) the deposition of the oxide coatings (**b**) and a schematic view of the experimental setup with a thermocouple sensor (**c**). CSEM-Macroscratch tester was used to examine coating adhesion up to a normal load of 50 N using an optical microscope and a traditional Rockwell-C diamond indenter. A sliding wear study using the diamond indenter of the macro scratch tester (normal load 10 N, linear speed 0.3 mm/s, testing duration 30 s) was used to calculate the coefficient of friction (COF). The experiments were carried out at room temperature and in the open. The sessile drop method was applied for the static contact angle measurements. Ethanol was used to clean the samples and get rid of any surface residue. Subsequently, each sample was subjected to three drops (5 \(\mu\)L) of distilled water to obtain reliable average readings. At room temperature, a set of three drops on each surface were photographed at a fixed 30 s interval. Water contact angles were measured and recorded with a standard deviation. Using Autodesk AutoCAD 2016, the contact angle values were determined from the obtained images. Potentiostat/galvanostat Interface 1010E (Gamry Instruments, Warminster, PA, USA) was used to conduct electrochemical testing in a simulated body fluid (SBF) solution. A working electrode with a 1 cm\({}^{2}\) exposed area in SBF solution, a platinum wire counter electrode, and a Ag/AgCl reference electrode were used in the three-electrode cell tests.