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• L-Pheand Zn(NO 3) 2 are efficient hybrid inhibitor for Mg alloys in NaCl solution. • Appropriate concentration and ratio between them are critical for inhibition effect. • The film is formed on metal surface including complicate composition. • Inhibition mechanism is proposed according to XPS and theoretical calculation. L-Phenylalanine (L-Phe) is a promising eco-friendly alternative to replace the conventional toxic inhibitors for magnesium alloys in NaCl solution. However, its inhibitory performance is not satisfied. The addition of slight amount Zn(NO 3) 2 would greatly refine the inhibitory efficiency. The inhibitory performance of hybrid inhibitor is explored by scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and various electrochemical measurements. The highest inhibitory efficiency of 93.2% is achieved for 0.30 mM L -Phe + 0.07 mM Zn(NO 3) 2. The amount of each inhibitor and the suitable match of two inhibitors are carefully determined, which are both critical items for the final performance. The possible inhibitory mechanism is conjectured by the XRD and XPS measurements along with the quantum chemical calculations. [Display omitted] [ABSTRACT FROM AUTHOR]

• Orange peel extracts effectively retard the corrosion for Mg alloys in NaCl solution. • The protective film is formed self-assembly after long time immersion in extracts. • Adsorption behavior follows Langmuir adsorption model. • Extracts present the better inhibition efficiency than single synthesized compound. Performance of orange peel extracts (OPE) to retard the magnesium alloys corrosion is thoroughly evaluated by Electrochemical impedance spectra (EIS) and potentiodynamic polarization curves. OPE would be an effective inhibitor with the efficiency of 85.7% at very low concentration of 0.030 g L −1. The inhibition effect of selected three pure components including in OPE is much inferior or comparable with that of OPE, whereas the cost of pure compounds is too expensive to be afforded. The protective self-assembly film would be formed on the magnesium surface by immersion in OPE. Structure characterization is performed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffractometer (XRD). The adsorption of OPE on magnesium surface follows the Langmuir adsorption rule with both chemical and physical interactions. The interaction between three selected pure compounds and magnesium alloys is further calculated by density functional theory (DFT). Moreover, the possible inhibition mechanism is constructed on the basis of above results along with the FTIR measurements. The low cost and green inhibitor is explored in this work, which would replace the expensive inhibitors with the similar or better performance. [ABSTRACT FROM AUTHOR]

Multifunctional composite coatings have been extensively used to protect metal substrates from corrosion. However, the use of ionic liquids (ILs) to modify the micro-arc oxidation/layered double hydroxides (MAO/LDHs) composite coating, to our best knowledge, has not been reported for the corrosion protection on metal substrates. It is thus necessary to prepare the ILs-modified MAO/LDHs composite coatings and understand in depth their corrosion resistance and active anticorrosive mechanism. Herein, a composite coating is constructed by introducing the MgAl-LDH modified by a choline 3-morpholinopropanesulfonate [Ch][MOPS] ionic liquid on an MAO film (CM-LDH/MAO). It is found that the CM-LDH/MAO composite coating shows the optimal corrosion protection on magnesium alloy, with a corrosion current density of 8.38 × 10−10 A cm−2, clearly lower than those of the MAO and LDH/MAO coatings. More importantly, a small pitting appears at the edge of the CM-LDH/MAO film only after long-term exposure of 216 h in 3.5 wt% NaCl solution. Such an improvement of corrosion resistance can be ascribed to the synergetic mechanism including the physical barrier of the composite coating, the self-repairing ability of the LDH nanosheets on the microporous flaws of the MAO film, as well as the formation effect of the Mg-based chelates by the adsorption of the [Ch]+ cations and the re-adsorption of the [MOPS]– anions released from the LDH interlayers. [ABSTRACT FROM AUTHOR]

Hydrogen storage is an essential technology for the development of a sustainable energy system. Magnesium (Mg) and its alloys have been identified as promising materials for hydrogen storage due to their high hydrogen storage capacity, low cost, and abundance. However, the use of Mg alloys in hydrogen storage materials requires a thorough understanding of the material properties and their behavior under different conditions. In this study, we established a database of Mg alloys properties and their hydrogen storage performance, which was then used to train various machine learning (ML) regression models with maximum hydrogen storage (Ab_max) and maximum hydrogen release (De_max) as outputs. These models possess excellent prediction accuracy. The GBR model for Ab_max and MLP model for De_max present highest accuracy with the R2 of the test set reaching 0.947 and 0.922, respectively. The Shapley additive explanations (SHAP) algorithm was then used to interpret the best ML models, and the critical values of important descriptors were obtained to guide the design of hydrogen storage materials. Finally, based on the best ML models, the Ab_max and De_max were predicted for the Mg-based binary alloys with other 16 metal elements and Mg–Ni-based ternary alloys with other 15 metal elements, respectively. Among them, 96Mg-4Sm and 95Mg–1Ni-4Sm have higher Ab_max and De_max of 6.31 wt% and 5.69 wt%, 6.64 wt% and 5.63 wt%, respectively, meeting the requirement of high Ab_max/De_max at the operating temperature below 300 °C. [Display omitted] • A database of Mg-based hydrogen storage materials was constructed. • High-precision machine learning models of maximum hydrogen storage/release were established. • The critical factors affecting hydrogen storage property of Mg alloys were revealed. • Potential excellent binary and ternary Mg alloys for hydrogen storage were predicted. [ABSTRACT FROM AUTHOR]

A new ionic liquid, benzyl triphenyl phosphonium bis(trifluoromethylsulfonyl)amide ([BPP][NTf 2 ]), for magnesium alloy is synthesized. The potential of [BPP][NTf 2 ] to be inhibitor is firstly estimated as compared with [P 6,6,6,14 ][NTf 2 ] by theoretical calculations. Then, the inhibition of AZ31B Mg alloy in 0.05 wt% NaCl solution is evaluated by [BPP][NTf 2 ] is investigated by Tafel linear polarization method, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The most optimum inhibitor efficiency of [BPP][NTf 2 ] is 91.4% at room temperature. The adsorption of [BPP][NTf 2 ] on the surface of AZ31B Mg alloy obeys Langmuir isotherm with predominantly chemical adsorption. The corresponding result is further analyzed by the theory. The corrosive product is detected by Fourier transform infrared spectrum (FTIR). The possible inhibition mechanism is proposed, in which the effect of cation on inhibition is proposed in addition to the influence of anion. Image 1 • Inhibitor behavior of [BPP][NTf 2 ] for Mg alloy is studied by combination of experiment and theory. • [BPP][NTf 2 ] is easy to be synthesized with cheap raw materials. • Inhibitor efficiency of [BPP][NTf 2 ] is as high as 91.4% in 0.05 wt% NaCl. • The adsorption of [BPP][NTf 2 ] obeys the Langmuir adsorption model. • The possible inhibition mechanism is proposed. [ABSTRACT FROM AUTHOR]

Electrophoretic deposition (EPD) is a coating technique which is widely applied to improve the biocompatibility and anticorrosive performance of medical metal alloys. In this paper EPD was employed to deposit bioactive glasses(BGs)-chitosan(CS) coating loaded with model drug tetracycline(TCH) on AZ31B magnesium alloy to enhance its anti-inflammation, anti-bacteria, anticorrosion and osteogenic induction properties. The electrochemical test showed that the corrosion current density of CS-BGs-1.0 TCH coating was 2 orders of magnitude lower than that of bare AZ31B. In vitro biological activity revealed that after 3 d of immersion in simulated body fluid, the surface of the coating was covered with a layer of hydroxyapatite. In vitro drug release test showed that the drug in CS-BGs-1.0 TCH could be effectively released for 504 h, providing resistance to the formation of bacterial film in a long time. In vitro antibacterial tests indicated that the coating significantly improved the antibacterial activity of magnesium alloy against E.coli. As a result, the prepared coating had better corrosion resistance, antibacterial and biological activity. This coating has good potential in the application of medical devices and bone implant materials. • The coating increases the corrosion resistance of magnesium alloys. • Tetracycline can be released continuously for a long time (504 h). • The coating loading tetracycline has obvious antibacterial effect on E.coli. • Hydroxyapatite formed on coating surface after 1 d in simulated body fluid. [ABSTRACT FROM AUTHOR]

[Display omitted] • The corrosion inhibition behavior of three dicationic ionic liquids were studied experimentally. • [DMBAB][Trp] 2 presents the best corrosion protection ability on AZ91D Mg alloy. • [DMBAB][Trp] 2 still has relatively high polarization resistance after 24 h of immersion in 0.5 wt% NaCl solution. Quaternary ammonium based ionic liquids (ILs) are considered as good corrosion inhibitors to protect substrates of metals such as carbon steel, copper and aluminum alloys against corrosion. However, studies applying them to the corrosion protection of magnesium (Mg) alloys still remain scarce. Herein, in this work, three quaternary ammonium based dicationic ILs, namely [DMBAB][MOPS] 2 , [DMBAB][Phe] 2 and [DMBAB][Trp] 2 were synthesized and applied as corrosion inhibitors to improve the corrosion protection ability on AZ91D Mg alloy in 0.5 wt% NaCl solution. Their corrosion inhibition performances were evaluated by electrochemical measurements, and the relevant corrosion results were investigated by extensive characterizations including scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Results show that the [DMBAB][Trp] 2 obtains an 88.8 % inhibition efficiency for AZ91D Mg alloy in 0.5 wt% NaCl solution, clearly higher than those of [DMBAB][Phe] 2 (80.4 %) and [DMBAB][MOPS] 2 (81.7 %). This suggests that [DMBAB][Trp] 2 presents the best corrosion protection ability on AZ91D Mg alloy among these ILs considered here, which is associated with the largest steric body and the most active adsorption sites of [DMBAB][Trp] 2 in comparison with other two compounds, hence resulting in a highest surface coverage. The present work offers a guidance for understanding the structure–property relationship of quaternary ammonium based dicationic ILs through a convenient, economical and effective way with a promising application in the field of material protection. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) coating has been widely applied for the magnesium alloys to resist the corrosion. However, the defaults on the PEO surface greatly weaken its long-term anti-corrosion performance. To fill the micropores is an efficient and feasible strategy to refine the compactness and anti-corrosion of PEO coating and achieve the additional function. Although various sealing pathways are reported in past decades, the leakage of filler and long-term anti-corrosion performance are still the perplexing issues. The corrosion inhibitor 1-methyl-3-(carboxyundecyl)imidazolium bis(trifluoromethylsulfonyl)imide ([MCIM][NTf 2 ], MN), is grafted on the clinochrysotile-like magnesium silicate nanotubes (MSNTs) by the post-synthesis method, then, the MSNTs@MN is filled into the micropores on the PEO surface by the post-sealing process to form PEO/MSNTs@MN. According to the electrochemical results in 3.5 wt% NaCl solution, the log |Z| 0.01Hz is increased by 1.26 times after the sealing. After immersion in 3.5 wt% NaCl solution for 120 h, the log |Z| 0.01Hz of PEO/MSNTs@MN is still the 1.56 times larger than that of PEO. The PEO coating filled by the MSNTs@MN offers the consistently superior corrosion resistance up to 336 h of salt spray tests with 5.0 wt% NaCl solution. The superior anti-corrosion performance of PEO/MSNTs@MN is associated with the cooperation of physical barrier of PEO coating and protection from MSNTs@MN. The grafted corrosion inhibitor would not leak easily, which is favorable to achieve the long-term anti-corrosion performance. The immobilized MN provides the active anti-corrosion in the initial corrosion stage achieving the self-healing function. Moreover, the release of corrosion inhibitor, MN, does not rely on the smart trigger, which broadens the scope of immobilized materials. This work introduces a facile and one-step strategy to seal the pores on the PEO surface with the self-healing function and improved anti-corrosion capability. [Display omitted] • Novel hybrid coating PEO/MSNTs@MN with self-healing and long-term anti-corrosion • A simple one-step strategy is introduced to seal the pores on the PEO surface. • The immobilized MSNTs@MN provides the active anti-corrosion functionalization. • Anti-corrosion feature is kept after 336 h salt spray tests in 5 wt% NaCl. [ABSTRACT FROM AUTHOR]

Smart coatings play crucial roles in realizing excellent corrosion protection on metals and alloys. However, the preparation of smart composite coatings exhibiting self-reporting and self-healing dual function still remains a challenge. Herein, a novel smart composite coating was successfully fabricated by incorporating the ionic liquid grafted carboxylated carbon nanotube and phenolphthalein into a micro-arc oxidation coating (MAO/PP/CCNT-IL) for AZ31B Mg alloy protection. The electrochemical tests including potentiodynamic polarization and electrochemical impedance spectroscopy reveal that the MAO/PP/CCNT-IL composite coating shows the best corrosion protection on the AZ31B Mg substrate among all coatings prepared in this work. In addition, the salt spray experiment in 5 wt% NaCl solution suggests that the occurrence of conspicuous pink within only 12 min can rapidly warn microdamage and microsurface damage, exhibiting a self-reporting effect. Meanwhile, the smart coating also presents outstanding healing property by reacting CCNT-IL with Mg ions from the substrates to generate the chelates to be covered on the damaged area. Such a smart coating offers a feasible strategy for prolonging the service lifetime of Mg alloys through a convenient, economical and effective way with a promising application in the field of material protection. [Display omitted] • A smart composite coating MAO/PP/CCNT-IL are prepared on the AZ31B Mg substrate. • The MAO/PP/CCNT-IL shows the best corrosion protection on the AZ31B Mg substrate. • The MAO/PP/CCNT-IL presents a dual function of self-reporting and self-healing. • The PP can rapidly identify the early stage of corrosion via the color change. • The CCNT-IL is covered on the exposed Mg substrate by forming CCNT-IL/Mg2+ chelate. [ABSTRACT FROM AUTHOR]

Anti-corrosion inorganic-organic hybrid coating with the self-healing feature is still scare for the Mg alloys. The adhesion between various compositions is one troublesome problem. On the other hand, the incorporation of corrosion inhibitor would destroy the feature of organic film leading to the inferior anti-corrosion performance. The hybrid coating, PEO/IN/QSE, with the self-healing feature is firstly fabricated on Mg alloys, in which the corrosion inhibitor of imidazolium-based ionic liquid (IN) is embedded in the plasma electrolytic oxidation (PEO) pores and the superhydrophobic film (QSE) is covered on the top. The IN embedded in the pores of PEO layer does not destroy the feature of QSE film and improve the anti-corrosion performance of PEO layer. And it affords the self-healing function, which is determined by the anti-corrosion test with the scratched samples. More important, it strengthens the adhesion between QSE and PEO coating as a bridge. This work provides a feasible strategy to prepare the inorganic-organic composite film with the promising applications for the anti-corrosion of the Mg alloys. [Display omitted] • Composite coating PEO/IN/QSE with self-healing and superhydrophobic feature • Adhesion between PEO and QSE layer is strengthened by IN. • The pores of PEO are taken as the container for IN corrosion inhibitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel hybrid coating is fabricated with superhydrophobic and self-healing features. • Anti-corrosion feature is maintained for 80 days immersion in 3.5 wt% NaCl. • Incorporation of [OTP][NTf 2 ] offers the self-healing as well as anti-corrosion. • Synergistic cooperation of various constituents results in the outstanding feature. Although Magnesium (Mg) alloys have many distinct advantages, they are vulnerable to the corrosion even in the neutral environment. Effective and feasible anti-corrosion strategies are desirable for the wide application of Mg alloys. A novel anti-corrosion composite coating, MAO (micro-arc oxidation)/[OTP][NTf 2 ] (octadecyl triphenyl phosphonium bis(trifluoromethylsulfonyl)amide)/PSE (superhydrophobic silica/epoxy resin), is fabricated for Mg alloys by combination of MAO, ionic liquid, and superhydrophobic coating. The employed [OTP][NTf 2 ] is incorporated into the pores of MAO coating rather than doped in the PSE coating. The successful preparation of composite coating is characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-corrosion feature is measured by potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5 wt% NaCl solution. The composite coatings maintain excellent corrosive resistance after 80 days immersion in 3.5 wt% NaCl solution. It is attributed to the synergistic effect of the superhydrophobic feature, the corrosion inhibition of [OTP][NTf 2 ], and the physical barrier of the MAO coating. Even if the coating is scratched, it still exhibits the excellent anti-corrosion performance after immersion in 3.5 wt% NaCl solution for 25 days due to the repair ability of [OTP][NTf 2 ]. The incorporation of [OTP][NTf 2 ] not only offers the self-healing feature but also seals the pores on the MAO surface, which is favorable to enhance the overall anti-corrosion performance of composite coating. [ABSTRACT FROM AUTHOR]

Fabricating layered double hydroxides (LDHs) coatings intercalated with corrosion inhibitors is considered an effective strategy for improving the corrosion resistance of metal substrates. However, to our best knowledge, studies applying LDHs coatings modified with ionic liquids (ILs) as environmentally friendly corrosion inhibitors to corrosion protection of metals and alloys have not been reported. In this contribution, two kinds of MgAl-LDHs coatings modified with imidazolium based dicationic ILs, namely LDH-C 6 (m 2 im) 2 -I and IL@LDH-C 6 (m 2 im) 2 -I, were successfully prepared on AZ31B magnesium alloy. The LDH-C 6 (m 2 im) 2 -I coating intercalated with C 6 (m 2 im) 2 -I ionic liquid was synthesized by the co-precipitation method and hydrothermal treatment, followed by a facile immersion experiment in a dimethyl sulfoxide solution containing C 6 (m 2 im) 2 -PF 6 ionic liquid to produce the IL@LDH-C 6 (m 2 im) 2 -I composite coating. The surface morphologies and anti-corrosion properties of the two MgAl-LDHs coatings immersed in 3.5 wt% NaCl solution were investigated. The present results reveal that the LDH-C 6 (m 2 im) 2 -I coating exhibits a uniform and dense petal-like nanoflowers structure, while the IL@LDH-C 6 (m 2 im) 2 -I composite coating contains a compact C 6 (m 2 im) 2 -PF 6 IL film and a lamellar-structured LDH-C 6 (m 2 im) 2 -I, which provides a double corrosion protection to the Mg alloy. As a result, the corrosion current density of IL@LDH-C 6 (m 2 im) 2 -I is only thirty-eighth of that of LDH-C 6 (m 2 im) 2 -I and 4 orders of magnitude lower than that of bare AZ31B Mg alloy. More importantly, the surface of samples coated with IL@LDH-C 6 (m 2 im) 2 -I is still compact without being destroyed after 168 h of immersion, which can be ascribed to the synergistic effect of excellent self-healing and durable corrosion resistance. This work opens a new way of preparing MgAl-LDHs coatings modified with ionic liquids to remarkably enhance the anti-corrosion performance of Mg alloys. [Display omitted] • IL@LDH-C 6 (m 2 im) 2 -I contains compact C 6 (m 2 im) 2 -PF 6 IL film and lamellar-structured LDH-C 6 (m 2 im) 2 -I. • The IL@LDH-C 6 (m 2 im) 2 -I coating shows better corrosion resistance on AZ31B Mg alloy than the LDH-C 6 (m 2 im) 2 -I coating. • The surface of samples coated with IL@LDH-C 6 (m 2 im) 2 -I remains continuous and complete after 168 h of immersion. [ABSTRACT FROM AUTHOR]

[Display omitted] • This statement is highlight for this manuscript as following. • Three imidazolium ionic liquids as green inhibitors were studied experimentally and theoretically. • Their corrosion inhibition behavior for the AZ31B Mg alloy was evaluated. • The possible corrosive products were estimated and inhibition mechanism was proposed. The corrosion inhibition behavior for the AZ31B Mg alloy in 0.5 wt% NaCl solution by three imidazolium-based ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [EMIm][NTf 2 ], 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [HMIm][NTf 2 ], and 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [DMIm][NTf 2 ] was explored by using electrochemical measurements coupled with theoretical computations. Scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used for the evaluation of the corrosion results. The present results reveal that the inhibition efficiency of three ILs on the Mg alloy follows the order: [DMIm][NTf 2 ] > [HMIm][NTf 2 ] > [EMIm][NTf 2 ]. This indicates that [DMIm][NTf 2 ] exhibits the best inhibition performance among these ILs studied, which may be ascribed to the largest steric body of [DMIm][NTf 2 ] with respect to other two analogues, thus leading to a highest surface coverage. In addition, adsorptions of all studied ILs obey the Langmuir isotherm with the character of dominantly chemical adsorption. Finally, the possible corrosive products were estimated and the inhibition mechanism was suggested. [ABSTRACT FROM AUTHOR]

In this contribution, walnut green husk extract (WGHE) is explored to be inhibitor for the magnesium alloys in the NaCl solution. According to the electrochemical measurements, the optimal inhibition efficiency is only 44.8% with 1.0 g L−1 WGHE. Moreover, it could not be further improved by increasing the concentration of WGHE. If the magnesium alloys samples are immersed in 1.0 g L−1 WGHE solution for 48 h, the inhibition efficiency is enhanced to 92.5% under the same corrosive environment. The menadione, one of components in WGHE, makes the major contribution for the corrosion resistance. The elements and chemical groups included in the corrosive products are confirmed by the X-ray diffractometer (XRD), fourier transform infrared spectrometer (FT-IR), and X-ray photoelectron spectroscopy (XPS) along with the molecular dynamics simulations and first principle calculations. The improved corrosion resistance is attributed to the complicate items including the adsorption of WGHE, the rupture of WGHE, and other reactions. This work is helpful to discover the green and biodegradable inhibitor from the agricultural waste for the magnesium alloys. [Display omitted] • Walnut green husk extract retard the corrosion of Mg alloys in NaCl solution. • Immersion can effectively improve the corrosion inhibition efficiency. • Menadione make a main contribution in the corrosion resistance. • Corrosion inhibition mechanisms are conjecture by both theoretical and experimental studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Environmentally adaptable ionic liquids protect Mg alloys in different environments. • The corrosion effect has good persistance and it can last for 7 days. • The ionic liquids can spontaneously form a dense film on the surface of Mg alloys. • The inhibition mechanism is studied by experiment and theoretical calculation. The influence of pyrazolium ionic liquid 1- n -butyl-2-decylpyrazole bistrifluoromethanesulfonimide ([BDePz][NTf 2 ]) on the corrosion behavior of AZ91D magnesium alloys in NaCl solution with three different concentrations and ASTM D1384-87 corrosive solution was explored by electrochemical measurements and SEM, AFM. Results revealed that as the concentration of Cl− increases, the corrosion inhibition performance of magnesium alloy inhibitor is slightly lower, but still good. The maximum corrosion inhibition efficiency is 90.4% in 0.05 wt% NaCl and 82.0% in ASTM D1384-87 corrosive solution. After soaking in the inhibitor-ethanol solution, the surface of the magnesium alloy is still relatively smooth after soaking in the four corrosion solutions for 7 d. The possible inhibition mechanism is proposed according to the XPS and XRD results as well as the molecular dynamics simulations and quantum chemical calculations. [ABSTRACT FROM AUTHOR]

The corrosion inhibition of Benzyltriphenylphosphonium chloride (BPP), l -Histidine (L-His), and mixed of them on magnesium alloys in 0.05 wt% NaCl is investigated by electrochemical measurements. The inhibition efficiency exceeds 90% with the suitable concentration as well as the ratio between BPP and L-His. Moreover, the inhibition effect would be kept even after the long term immersion in NaCl. It is attributed to the formation of inhibitor-coating film, which is further supported by the scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffractometer (XRD). Finally, the possible inhibited mechanism is proposed according to X-ray photoelectron spectroscopy (XPS) analysis and the density functional theory calculation. Image 1 • Synergistic effect of two inhibitors on Mg alloys corrosion is investigated. • Both concentration and ratio of inhibitors are critical for retarding the corrosion. • High inhibition efficiency would be kept even after long time immersion in NaCl. • Protective film is formed on the Mg alloys surface by adsorbed inhibitors. • Inhibition mechanism is proposed according to XPS and theoretical calculation. [ABSTRACT FROM AUTHOR]

• Inhibition behavior of three novel ionic liquids for Mg alloy is studied. • The highest inhibition efficiency is 91.9% for [OTP][NTf 2 ] in 0.05 wt.% NaCl. • The inhibition efficiency is improved with the substituted elogation of alkyl chain. • The possible inhibition mechanism is proposed by theoretical and XPS result. Three ionic liquids, decyl triphenyl phosphonium bis(trifluoromethylsulfonyl)amide ([DTP][NTf 2 ]), tetradecyl triphenyl phosphonium bis(trifluoromethylsulfonyl)amide ([TTP][NTf 2 ]), and octadecyl triphenyl phosphonium bis(trifluoromethylsulfonyl)amide ([OTP][NTf 2 ]), are firstly synthesized and their corrosion inhibition for AZ31B magnesium alloys in 0.05 wt.% NaCl solution is measured by electrochemical tests. The surface morphology is determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which testifies the formation of protective films on Mg alloy surface. The inhibition mechanism is further elucidated by X-ray photoelectron spectroscopy (XPS), first principle calculation along with molecular dynamics (MD). Possible inhibited mechanism is proposed finally. The highest inhibition efficiency is 91.9% by addition of 0.30 mM [OTP][NTf 2 ] in corrosive media. [ABSTRACT FROM AUTHOR]