SEM is a potent imaging method utilized to evaluate, at extreme magnification, the surface shape and characteristics of materials. SEM was used in this work to evaluate the mild steel specimens’ surface features and morphological alterations (Swathi et al., 2023a; Chukwunyere and Egbosiuba, 2023). Once the samples were exposed to the corrosive atmosphere for 6 hours, both with and without Prinivil, they were meticulously prepped and positioned on SEM stubs. The surface topography was acquired by the SEM visuals, which made it possible to assess surface pitting, corrosion byproducts, and the expansion of a defensive layer upon the metallic surface. The effects of Prinivil as a potent corrosion inhibitor were demonstrated visually by the high-resolution SEM visuals.

The samples were prepared by immersing mild steel specimens in 1 M HCl solution with and without 500 ppm of Prinivil for 6 h (Sharma et al., 2022). EDX analysis was conducted using an SEM equipped with an EDX detector. The EDX spectra were collected from representative areas of the sample surfaces to identify the elemental composition of the corrosion products (Kaur et al., 2022; 2023; Nidhi and Kaur, 2022). The obtained EDX spectra were analyzed to determine the presence and relative abundance of elements such as Fe, N, C, O, and any other relevant elements.

CA measurement is a procedure utilized to evaluate the wettability and surface energy of materials. In the context of corrosion mitigation, CA measurements offer insights into the emergence of a hydrophobic defensive layer upon the surface of mild steel. A contact angle goniometer was utilized in this research to measure the contact angle formed between the corrosive solution and the metallic surface (Andrés Coy-Barrera et al., 2023; Yadav et al., 2023a; Martinović et al., 2023). The contact angle is impacted by the interfacial forces between the liquid, solid, and gas phases, and a higher contact angle indicates a less wettable surface. It suggests the development of a hydrophobic layer that can act as an obstacle against corrosive species. The CA measurements aid in the understanding of the potential formation of a protective layer facilitated by Prinivil.

PDP is a key electrochemical methodology utilized to analyze corrosion behavior and, I.E., % in metals exposed to corrosive environments. By measuring current density as the metal is subjected to varying potentials, PDP generates polarization curves. These curves help determine E_corr and i_corr, crucial parameters for understanding corrosion rates. PDP also assesses the potential of corrosion inhibitors by comparing curves with and without inhibitors (Merimi et al., 2023a; Dong et al., 2023b). In current PDP measurements, the metal specimen was exposed to a range of elevated concentrations of inhibitor in a corrosive solution. The E_corr, i_corr, and Tafel slopes for both anodic (β_a) and cathodic (β_c) reactions were evaluated from the linked polarization variables, as detailed in Table 2. The polarization plots have been illustrated in Figure 3. As the prinivil dosage elevated from 50 ppm to 500 ppm, the corrosion inhibition mechanism underwent a transition, primarily owing to the enhanced adsorption of inhibitor molecules on the metal surface (Hadisaputra et al., 2023; Motawea and Melhi, 2023). At lower concentrations, the inhibitor molecules predominantly adsorb on the anodic sites of the metallic surface, where they hinder the oxidation reactions responsible for corrosion. However, as the inhibitor dosage rises, more inhibitor molecules adsorbed not only on the anodic sites but also on the cathodic sites of the metallic surface. This increased adsorption on both anodic and cathodic sites leads to a shift in the corrosion inhibition mechanism towards the cathodic side. The inhibitor molecules form a protective layer over the metal surface, inhibiting both anodic and cathodic corrosion processes effectively. This shift in the mechanism highlights the importance of inhibitor concentration in modulating the corrosion inhibition efficiency and the overall protection of the metallic surface against corrosion. The, I.E., % of the inhibitor was calculated using Equation 4.

Figure 3 and Table 2 demonstrate the potency of prinivil in mitigating corrosion of mild steel, with higher concentrations culminating in greater, I.E., % and surface coverage. As observed, the concentration of prinivil, ranging from 0 ppm (blank) to 500 ppm, indicates the varying dosages of the inhibitor tested in the experiment. As the concentration increases, there is a noticeable shift in the -E_corr towards less negative potentials, decreasing from 513.81 mV (blank) to 451.49 mV (500 ppm). This shift suggests that higher concentrations of prinivil effectively suppress corrosion initiation by developing a defensive barrier on the metallic surface which means that the inhibitor has more effect on the anode process than the cathode. It could be stated that the studied inhibitor is a mixed inhibitor (because the values of E_corr displacement for all concentrations do not exceed ±85 mV) with more effect on the anodic process. Concurrently, the i_corr decreases from 718.41 µA (blank) to 92.77 µA (500 ppm), indicating a drop in the rate of corrosion with increasing inhibitor dosage. The drop in i_corr signifies the effectiveness of prinivil in slowing down the corrosion process on the mild steel surface. The β_a and β_c values also exhibit a decreasing trend with increasing prinivil concentration (Abeng et al., 2023). The decrease in β_a (from 189.46 mV/dec to 109.26 mV/dec) and β_c (from 145.56 mV/dec to 115.4 mV/dec) suggests a reduction in the rates of both cathodic and anodic corrosion phenomenon. This reduction in corrosion rates is further supported by the decrease in C_R values, which decrease from 17.185 mm/yr (blank) to 1.3685 mm/yr (500 ppm). Furthermore, the, I.E.,% increases from not applicable (blank) to 87.08% (500 ppm), indicating a higher degree of corrosion inhibition achieved with higher concentrations of prinivil. This increase in inhibition efficiency is accompanied by a corresponding increase in surface coverage (χ²) values, which increase from 2.175E-07 (blank) to 1.0145E-06 (500 ppm). The higher surface coverage demonstrates that more inhibitor molecules adsorb onto the metallic surface, leading to enhanced corrosion protection. The observed trends in E_corr, i_corr, Tafel slopes, C_R, I.E., %, and surface coverage collectively indicate the corrosion inhibition potential of prinivil and its ability to protect mild steel surfaces from corrosive environments.

The investigation of Nyquist plots offers valuable information about the impedance behavior of corrosion inhibitors in acidic environments. In this study, Nyquist plots were obtained for inhibitor dosage ranging from 50 ppm to 500 ppm, alongside corresponding blank samples, providing critical information on the inhibition efficiency and impedance characteristics. The Nyquist plots revealed distinct differences between the inhibitor-containing samples and the blank samples. As depicted in Figure 4, at lower inhibitor concentrations (50 ppm and 100 ppm), the plots exhibited intermediate impedance values, indicating a moderate inhibition effect on the corrosion process (Dong et al., 2023b). The presence of inhibitors led to an elevation in the R_CT compared to the blank samples, suggesting a reduction in the C_R. As the inhibitor concentration increased (200 ppm, 300 ppm, and 500 ppm), further enhancements in impedance behavior were observed. The Nyquist plots showed higher R_CT values for the inhibitor-containing samples, signifying a more pronounced inhibition effect. This increase in impedance suggested a greater hindrance to the corrosion process, resulting in improved corrosion protection. Moreover, the comparison between the R_CT values of inhibitor-containing samples and blank samples highlighted the effectiveness of the inhibitors in mitigating corrosion (Swathi et al., 2023a). The inhibitor-containing samples consistently exhibited higher R_CT values, indicating superior corrosion inhibition performance compared to the blank samples. Additionally, as inhibitor concentration increases, the capacitive circle in Nyquist plots continues to expand, which indicates improved corrosion, I.E., % and related alterations to the electrochemical dynamics of the system (Pour-Ali et al., 2023a). This phenomenon may be explained by the inhibitor molecules adhering to the metallic surface and creating a barrier that prevents corrosion. At lower inhibitor concentrations, the capacitive loop exhibited moderate enhancement, indicating a partial inhibition effect. As the inhibitor concentration increased, the capacitive loop became more pronounced, signifying a stronger inhibition effect and improved corrosion protection. This behavior is indicative of the inhibitor’s ability to hinder the electrochemical reactions responsible for corrosion, such as metal dissolution and oxygen reduction.

The mechanism underlying the increasing capacitive loop involves the emergence of an adsorbed inhibitor coating on the metallic substrate (Huang et al., 2023). This layer behaves as a physical obstacle, preventing direct contact between the corrosive environment and the metallic substrate. Additionally, the inhibitor molecules might offer chemical reactions with the metallic substrate, developing a defensive layer that further impedes corrosion processes. Furthermore, the elevation in the capacitive loop corresponds to an elevation in the R_CT observed in Nyquist plots. This elevation in R_CT suggests a lessening in the rate of electron transfer reactions at the metal-electrolyte interface, culminating in decreased corrosion rates. Additionally, the appearance of a diffusion tail at high inhibitor concentrations (300 and 500 ppm) in Figure 4 indicates a notable alteration in the transport dynamics of ions or molecules within the electrolyte solution. This phenomenon typically arises due to the presence of the inhibitor, which impedes the free movement of species through the solution. The inhibitor formed a protective layer on the electrode surface or modified the transport properties of the electrolyte solution. The formation of a protective layer, often initiated by the adsorption of inhibitor molecules onto the electrode surface, creates a barrier that restricts the diffusion of ions or molecules toward the electrode interface. This protective layer serves as a shield against corrosive species, thereby reducing the rate of corrosion. Additionally, the inhibitor might induce changes in the transport properties of the electrolyte solution itself. For instance, the presence of inhibitor molecules can alter the viscosity or conductivity of the solution, affecting the mobility of ions and molecules within the electrolyte. As a result, the diffusion of species towards the electrode surface becomes hindered, leading to the observed diffusion tail in the EIS data.

The examination of capacitive behavior through Bode plots offers valuable insights into the efficacy of corrosion inhibitors across different concentrations. In this study, Bode plots (Figure 5) were generated for inhibitor dosage varying from 50 ppm to 500 ppm in an acidic environment of 1 M HCl. At lower inhibitor concentrations (50 ppm and 100 ppm), the Bode plots exhibited deviations from ideal behavior, with phase angles diverging notably from the desired 90°. This divergence suggested a less favorable capacitive response and hinted at potential limitations in corrosion inhibition effectiveness at these concentrations (Tolulope Loto, 2023; Wang et al., 2023). However, as the inhibitor concentration increased (200, 300, and 500 ppm), notable improvements in capacitive behavior were observed. The curves began to approach the desired characteristics, with phase angles aligning more closely with the ideal 90°. This trend indicated a more favorable capacitive response and suggested enhanced corrosion, I.E.,% at higher inhibitor dosage. The optimization of capacitance at intermediary frequencies holds significant implications for corrosion prevention strategies. By achieving a more optimal capacitive behavior, inhibitors can better protect metallic surfaces from corrosive attacks in acidic environments. For the fitting of the acquired data an equivalent circuit used was used (Supplementary Figure S2). These findings underscore the importance of concentration-dependent effects on corrosion inhibition efficacy and provide valuable guidance for the emergence of more potent corrosion control measures.

Table 3 deliberates an overview of the corrosion mitigation effectiveness of mild steel in a highly corrosive 1 M HCl solution when subjected to varying concentrations of inhibitor (50–500 ppm) at 298 K. The inclusion of electrochemical parameters such as the constant phase element (CPE.Yo), exponent (n), solution resistance (R_s), polarization resistance (R_p), and charge transfer resistance (R_ct) provide insightful information about the inhibitor’s inhibition effectiveness and corrosion behavior. The results presented in Table 3 indicate a clear trend towards increased inhibition efficiency with higher concentrations of the inhibitor (Al-Amiery et al., 2023; Yadav et al., 2023b; Narang et al., 2023). For instance, at 50 ppm concentration, the, I.E., % is recorded at 61.37%, demonstrating a substantial lessen in the C_R compared to the uninhibited condition. As the inhibitor concentration rose to 500 ppm, the, I.E., % value significantly rose to 97.35%, indicating a remarkable improvement in corrosion protection. Furthermore, the values of R_ct offer valuable info about the potency of the inhibitor in impeding the corrosion process. A higher R_ct value of 395.55 Ωcm² corresponds to lower corrosion activity, indicating that the inhibitor successfully impedes the corrosion-causing charge transfer processes. The observed increase in R_ct with rising inhibitor concentration corroborates the enhanced inhibition efficiency observed in the, I.E., % values. The values of R_s across different inhibitor concentrations reveal notable variations. For instance, at 50 ppm of Prinivil, R_s is recorded at 1.673 Ω, indicating relatively low resistance to ionic flow. As the concentration of Prinivil increases to 500 ppm, R_s increases to 4.879 Ω(Alamry et al., 2023; Fawzy et al., 2023b). This elevation in Rs suggests reduced ionic conductivity of the solution, which could facilitate reduction in the electrochemical processes at the metal-electrolyte interface, which results in enhanced corrosion inhibition.

In contrast, R_p values demonstrate the corrosion resistance of the metallic surface in the existence of Prinivil. At 50 ppm, R_p is measured at 23.946 Ω, indicating a moderate level of polarization resistance. As the concentration of Prinivil increases, R_p also rises steadily, reaching 398.28 Ω at 500 ppm. These increasing R_p values suggest improved corrosion resistance conferred by the inhibitive layer formed by Prinivil upon the metallic surface. Additionally, the degree of surface coverage (ɵ) values reflect the extent to which the inhibitor molecules adhere to the surface of the mild steel, developing a defensive coating against corrosion. The data demonstrates a proportional increase in ɵ with rising inhibitor concentration, indicating greater surface coverage and adsorption of inhibitor molecules on the metallic surface (Merimi et al., 2023b; Shetty et al., 2023). Moreover, the consistency of the goodness of fit parameter (χ²) across different inhibitor concentrations indicates the robustness and reliability of the electrochemical measurements and data analysis techniques employed in the study. This reinforces the validity of the results and underscores the accuracy of the reported inhibition efficiencies and surface coverage values.

In this study, SEM analysis was conducted to examine the surface morphology and corrosion behavior of mild steel samples subjected to different conditions. After a 6 h immersion in a 1 M HCl solution at 298 K, SEM analysis was performed on three distinct samples to evaluate their corrosion characteristics. The SEM micrograph of the plain metallic sample (Figure 9A) displayed a relatively smooth surface, indicating minimal corrosion in the absence of any inhibiting agent (Nesane et al., 2023). In contrast, the SEM analysis of the metallic sample (Figure 9B) immersed solely in the 1 M HCl solution showed significant corrosion damage, characterized by the existence of numerous corrosive pits distributed across the surface. Remarkably, the SEM micrograph of the metallic sample (Figure 9B) immersed in the 1 M HCl solution with the introduction of a 500 ppm inhibitor exhibited significantly fewer corrosive pits compared to the sample immersed in the acidic solution alone. The enhanced presence of corrosion products in Figure 9C compared to Figure 9B can be attributed to the protective action of the inhibitor. When the mild steel sample was immersed in the acidic solution alone, without the inhibitor, it was more susceptible to corrosion attack, leading to the formation of corrosion products. However, when a 500 ppm inhibitor concentration was introduced, the inhibitor formed a protective layer on the metal surface, inhibiting the corrosion process. This protective layer prevented the formation of extensive corrosion products, resulting in fewer corrosive pits and a smoother surface appearance. Therefore, the more pronounced corrosion products in Figure 9C indicate the effectiveness of the inhibitor in mitigating corrosion and preserving the integrity of the metal surface (Bedair et al., 2022; Sanni et al., 2022). The inclusion of the prinivil led to a notable reduction in the formation of corrosive pits, underscoring its potential for corrosion protection in acidic environments.

The EDX analysis revealed differences in the elemental composition of the corrosion products between the blank sample and the sample treated with Prinivil (Kaya et al., 2023a; 2023b; Arifa Farzana et al., 2023; Sharma et al., 2023a; Dhonchak and Agnihotri, 2023). The EDX analysis depicted in Supplementary Figure S3 illustrates the elemental composition of mild steel samples subjected to different environments. In the sample immersed (a) in 1 M HCl solution, Fe dominates at 87.31 wt%, consistent with mild steel composition, accompanied by C at 6.19 wt% and O at 6.84 wt%, indicating surface oxidation typical of acidic environments. Conversely, in the sample treated (b) with 500 ppm Prinivil in 1 M HCl solution, iron remains dominant at 87.80 wt%, with increased carbon (8.01 wt%) and slightly reduced oxygen (5.44 wt%). Notably, nitrogen (4.04 wt%) is detected in the Prinivil-treated sample, indicating the presence of the inhibitor on the metal surface (same as mentioned in Table 6) (Thakur et al., 2022; 2023a; 2023b; Sharma et al., 2023b). This suggests adsorption or chemical bonding of Prinivil molecules, contributing to a protective layer that inhibits corrosion. The higher carbon and oxygen content in the treated sample may imply the formation of a more stable oxide layer, enhancing corrosion resistance.

The contact angle analysis is a crucial procedure for observing the surface attributes of materials and understanding their interactions with liquids. In this study, contact angle measurements were conducted following 6 h of dipping in 1M HCl media, both with and without the existence of a corrosion inhibitor. The sample (Supplementary Figure S4A) illustrates the contact angle measurement of the pristine polished metal before dipping into the blank solution with an angle of 98.24°. The sample dipped in 1M HCl media (Supplementary Figure S4B) exhibited a contact angle of 49.64°. This relatively low contact angle indicates a moderate wetting behavior, suggesting that the acid solution interacts relatively strongly with the surface of the material (Alotaibi et al., 2022; Naggar et al., 2022; Quadri et al., 2022). On the other hand, the sample immersed in 1M HCl media containing 500 ppm of the inhibitor (Supplementary Figure S5C) revealed a significantly higher contact angle of 84.27°. This substantial increase in contact angle indicates a pronounced change in surface properties, likely attributed to the existence of the corrosion inhibitor. The higher contact angle suggests improved hydrophobicity or reduced surface wettability in the inclusion of the inhibitor, indicating the emergence of a defensive coating upon the material’s surface. This observation aligns with the corrosion inhibition efficacy results attained from other analytical techniques in the study.

It is well documented in the literature that heteroatom-containing compounds such as nitrogen and oxygen in their molecular structures are often excellent corrosion inhibitors. Indeed, these compounds can be adsorbed by their free doublets onto the metallic surface, blockage of active sites and therefore reduction of corrosion rate. The efficiency of molecules is linked to their electronic properties: electron density on atoms and the character of HOMO and LUMO orbitals. According to Fukui’s theory, the HOMO and LUMO boundary molecular orbitals could be utilized to predict the reactivity of the inhibitor toward the metallic surface. This theory is based on the principle that only Frontier molecular orbitals are of real interest when studying a chemical reaction with Frontier control (Kalkhambkar and Rajappa, 2022; Swathi et al., 2022). HOMO energy is often linked to the molecule’s capacity to release electrons into available orbits. Conversely, LUMO offers details on the molecule’s ability to receive electrons. The gap between the inhibiting molecule’s HOMO and LUMO energy levels is another crucial metric since low energy gap values suggest effective inhibition. Figure 10 displays the electron density distributions of the HOMO and LUMO molecular orbitals prinivil (low pH) and prinivil inhibitors, as well as the molecular Frontier orbitals.

It could be observed that the electron density of the LUMO location was distributed almost throughout the molecule, because of the existence of oxygen, nitrogen, and carbon atoms, including multiple electrons of chemical configurations of inhibitors prinivil (low pH) and prinivil studied. Thus, the iron atom’s unoccupied orbit may receive electrons from inhibitory molecules to form coordination bonds. Inhibitory molecules may also accept electrons of the iron atom with its anti-binding orbitals to form bonding bounds in return (Burhagohain et al., 2022; Shao et al., 2022). ESP analysis is used as a fundamental tool to study the behavior of atoms and molecules; various non-covalent molecular interactions and properties have been well interpreted by ESP analysis. ESP mapping makes it easier to see where a molecule’s electron density is especially high or low, emphasizing the molecule’s reactive regions. Red represents the locations with the highest negative electrostatic potential, while blue indicates the regions with the highest positive electrostatic potential. As demonstrated by the ESP mappings of the chemical species under investigation in Figure 10. From the figure above, the most negative electrostatic potential is distinctly localized to atoms O and N, indicating that these atoms may be the main contributors to the coordination process with ions. The theoretical study of the prinivil (low pH) and prinivil inhibitors, allowed us to identify a number of structural and electronic parameters of the systems studied. The parameters are gathered in Table 7.

E _HOMO values evolve in the direction: prinivil > prinivil (low pH), which explains why the prinivil molecule has a higher electron-donating capacity than prinivil (low pH). While E _LUMO follows the order prinivil (low pH) <prinivil, this means that prinivil (low pH) has greater electron acceptor capacity than prinivil. Additionally, the prinivil (low pH) molecule is softer (σ = 0.444) and possesses the minimum ΔE value (4.506 eV), that facilitates its adsorption on the substrate and thus increases its, I.E.,%. Moreover, the theoretical value of iron (χ_Fe = 4.82 eV and η_Fe = 0) is utilized for calculating the proportion of inhibitor ΔN on the surface of MS(Kucharski et al., 2022; Said et al., 2022). The, I.E., % that results from electron donation is related to the ΔN values. Lukovit’s research indicates that when ΔN is less than 3.6, the, I.E., % rises along with the capacity to contribute electrons to the metallic surface. In our research, the prinivil (low pH) and prinivil presented values below 3.6 following the order prinivil (low pH) > prinivil and therefore, the latter are electron donating inhibitors and the metallic substrate is an acceptor.

The computed Mulliken charges of the atoms are displayed in Supplementary Figure S5. Examination of these results shows that negatively charged atoms with high electron density behave as nucleophilic sites when engaging with the substrate, while positively charged atoms can accept electrons from the metal (Mahadevaswamy et al., 2022; Priyanka and Nalini, 2022). The values in Supplementary Figure S5 show that all nitrogen and oxygen atoms exhibit a significant excess of negative charge. Some carbon atoms are also likely to be active sites for the adsorption of the inhibitors tested to the metallic surface. As a consequence, the corrosion rate is reduced.

Fukui model indices are employed to clarify the localized reactivity of several chemical inhibitors. It follows that the atoms whereby the metal’s surface adsorption process takes place could be assumed. Accordingly, the locations with an elevated f _k ⁺ value are those that the f _k ⁺ prefers, and the places with the lowest f _k ^–values are those that the f _k ^–finds attractive. Table 8 comprises the Fukui indices derived from the Mulliken charges technique for prinivil (low pH) and prinivil inhibitors forms (Hameed et al., 2021; Khiev et al., 2021; Lu et al., 2021). Table 8 could be used to identify appropriate sites for the f _k ⁺ and f _k ^–assault for the prinivil under investigation. This inhibitor is more effective in the instance of compound prinivil (low pH) than it is in the case of the prinivil inhibitor. The most effective sites are C, O and N atoms with an improved attack attribute, which are O (1), C (6), O (16), O (17) and O (26) for prinivil (low pH) and O (1), C (6), N (12) and O (26) for prinivil as listed in Table 8.

Monte Carlo (MC) and Molecular Dynamics (MD) simulations are broadly employed in scientific research to explore the interactions between inhibitory molecules and metallic surfaces. These computational techniques offer valuable insights into the equilibrium adsorption configurations of inhibitors on metal surfaces and their inhibitory effectiveness (Abdollahi et al., 2020; Ma et al., 2020; Raghavendra, 2020). In a specific case involving prinivil (low pH) and prinivil inhibitors on the Fe (1 1 0) surface, both MC and MD simulations reveal that the inhibitors adopt a nearly plane-parallel orientation upon adsorption (Figure 11). This orientation proves advantageous as it facilitates efficient adsorption onto the carbon steel surface, effectively blocking a maximum number of active sites. Consequently, this configuration enhances the inhibitory efficacy of the inhibitors by providing extensive surface coverage and minimizing the potential for corrosion or other detrimental processes. MC and MD simulations make a substantial contribution to the comprehension of corrosion inhibition processes and facilitate the development of more potent inhibitors by elucidating the behavior of inhibitory compounds on metallic surfaces. The adsorption energies for the prinivil (low pH) and prinivil compounds are displayed in Supplementary Figure S6. The energy produced during the adsorption of the relaxed components adsorbed onto the substrate is the cause of the E_ads. The adsorbent component’s stiff strain and adsorption energies add up to the E_ads. A higher interaction between an inhibitory molecule and a Fe (1 1 0) is indicated by high negative Eads values. These findings indicate that the inhibitory potency of the chosen chemicals is arranged as follows: prinivil (low pH) (E _ads = −287.35 kcal/mol) > prinivil (E _ads = −152.95 kcal/mol).

The radial distribution function (RDF) in MD simulations is a useful tool for surface-molecule interaction analysis. References demonstrate how extensively the RDF (shown in Figure 12), commonly referred to as “g,” has been studied in the literature (Chauhan et al., 2018; Soltaninejad and Shahidi, 2018). The RDF peak for physisorption is larger than 3.5 Å, while the pinnacle for chemisorption is between 1 and 3.5 Å. As demonstrated, the proximity of prinivil (low pH) and prinivil compounds to the metallic surface shows that both inhibitors and the metallic surface have a reasonably strong connection. This corroborates the inhibitors’ reflected inhibitory efficiency.