Rising of MXenes: Novel 2D-functionalized nanomaterials as a new milestone in corrosion science - a critical review

Functionalized MXene composites for protection on metals in electric power

Metals used in electric power suffer from icing, wear, and corrosion problems, resulting in high energy consumption, economic losses, security risks, and increased CO2 emission. To address these problems, researchers have turned to two-dimensional (2D) transition metal carbide or nitride (MXene) materials, which possess strong near-infrared adsorption, photothermal conversion, shear ability, low friction coefficient, and impermeability. These properties make MXene a promising candidate for surface protection on metals in electric power, including anti-icing, anti-wear, and anti-corrosion applications. However, the comprehensively protective ability and the promising application of MXene in electric power have not yet been reported. In this review, recent progress in MXene-based composites for anti-icing, anti-wear, and anti-corrosion in electric power is summarized to understand the protective mechanisms and the promising applications. First, the chemical and structure of MXene are briefly introduced, followed by a summary of its intrinsic properties. Next, the latest research on deicing MXene composite coatings, anti-wear MXene-based composites and coatings, and anti-corrosive MXene coatings, along with the corresponding mechanisms, is discussed. Finally, the challenges and opportunities of MXene-based composites in electric power are highlighted. This review provides guidance for understanding the comprehensively protective abilities of MXene and rationally designing MXene-based materials used in electric power.

Ti3C2Tx MXene/MoS2 hybrid nanocomposites for synergistic smart corrosion protection of epoxy coatings

MXene nanosheets have recently become a focus of research for corrosion protection due to their two-dimensional, sheet-like structure and distinct physicochemical characteristics. Nevertheless, their susceptibility to restacking and oxidation restricts their practical applications. To address this, the study proposes a custom hybrid structure by growing molybdenum disulfide (MoS2) nanoparticles on the Ti3C2 MXene nanosheets (MX/MS) to prevent oxidation and restacking. This innovative structural design is essential for corrosion-protective coatings, as the sheet-like configuration enhances the barrier properties. The manufacturing of the MX/MS nanoparticles was verified by their characterization employing field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The barrier properties and self-healing functions of the nanoparticle-filled epoxy coatings were evaluated using electrochemical impedance spectroscopy (EIS) and salt spray tests. The epoxy resin including 0.5 wt% MX/MS nanoparticles exhibited outstanding corrosion resistance, with an impedance value (|Z|0.01Hz) of 23.77 GΩ.cm2 after 70 days of immersion. After 48 h of immersion, the coatings also showed a high impedance value (log|Z|0.01Hz = 4.24) and excellent self-healing capabilities in the scratched areas. Additionally, after 42 days, the filled nanohybrid coatings showed the least amount of rust and corrosion product according to salt spray analysis. The results of cathodic delamination and pull-off tests indicated that in comparison to the neat epoxy (11 mm and 70 %), the filled coatings containing the synthesized nanofiller had the lowest cathodic delamination radius (1.7 mm) and lowest adhesion loss (46 %). This study highlights the effectiveness of Ti3C2/MoS2 hybrid in enhancing the anticorrosive performance of organic coatings, offering a novel approach for designing high-performance additives with promising applications in various fields requiring corrosion protection.

Emerging two dimensional MXene for corrosion protection in new energy systems: Design and mechanisms

With the development of new and clean energy (offshore wind power, fuel cells, aqueous zinc ion batteries, lithium-ion batteries, etc.), the corrosion and security problems in special environments of the new energy system have attracted much attention. Corrosion protection on the metals applied in new energy system can reduce the economic loss, security risk, and energy consumption, as well as guarantee the efficiency of energy system. Traditional coatings face challenges in agglomeration of nano fillers, structural control, environmental issues, and poor conductivity, which limits the applications. With features in controllable surface chemistry and composition, rich surface terminations, better conductivity than graphene oxide, high aspect-ratio, strong impermeability, and low friction coefficient, the two-dimensional (2D) MXene presents potential for applications in corrosion protection in new energy systems. Despite progress has been made in the MXene for corrosion protection, there is still a lack of comprehensive review regarding the design and mechanisms of anti-corrosive MXene-based materials for corrosion protection in new energy system. In this review, a brief induction of MXene and the specially four corrosive environments (offshore wind power at deep sea, bipolar plates in PEMFC environments, zinc anode in AZIBs, and current collectors in Li-ion battery) are presented. Importantly, the design strategies and mechanisms of the MXene-based anti-corrosive coatings on metals used in the special environments are discussed in detail. Finally, the challenges and research trends in the MXene-based coatings for new energy systems are prospected. This review provides further understanding of corrosion in new energy and would expand the application prospects of MXene.

Self-Healing Superhydrophobic Coatings with Multiphase Repellence Property

Developing versatile, scalable, and durable coatings that repel various matters in different service environments is of great importance for engineered materials applications but remains highly challenging. Here, the mesoporous silica microspheres (HMS) fabricated by the hard template method were utilized as micro-nanocontainers to encapsulate the hydrophobic agent of perfluorooctyltriethoxysilane (F13) and the corrosion inhibitor of benzotriazole (BTA), forming the functional microsphere of F-HMS(BTA). Moreover, the synthesized organosilane-modified silica sol adhesive (SMP) and F-HMS(BTA) were further employed as the binder and functional filler to construct a superhydrophobic self-healing coating of SMP@F-HMS(BTA) on various engineering metals through scalable spraying. The prepared coating exhibits good mechanical durability and strong resistance to accretion of multiphase substances including large molecule compounds, liquids, and ice crystals, demonstrating good antifouling and anti-icing properties. Moreover, the coatings possess hydrophobic and anticorrosion self-healing properties owing to the self-migration release of the functional additives in the micro-nanocontainers, showing the "active-passive" synergistic properties mechanism. At a frequency of 0.01 Hz, the charge transfer resistance Rct and the constant phase element Ccpe were measured to be 2.62 × 109 Ω cm2 and 9.63 × 10-10 F cm2, respectively. In addition, the corrosion current density was reduced by 3-5 orders of magnitude, indicating superior corrosion resistance. This work provides a feasible strategy to prepare functional protective coatings for a wide range of applications in addressing adhesion and corrosion issues.

2D materials for Tribo-corrosion and -oxidation protection: A review

The recent rise of 2D materials has extended the opportunities of tuning a variety of properties. Tribo-corrosion, the complex synergy between mechanical wear and chemical corrosion, poses significant challenges across numerous industries where materials are subjected to both tribological stressing and corrosive environments. This intricate interplay often leads to accelerated material degradation and failure. This review critically assesses the current state of utilizing 2D nanomaterials to enhance tribo-corrosion and -oxidation behavior. The paper summarizes the fundamental knowledge about tribo-corrosion and -oxidation mechanisms before assessing the key contributions of 2D materials, including graphene, transition metal chalcogenides, hexagonal boron nitride, MXenes, and black phosphorous, regarding the resulting friction and wear behavior. The protective roles of these nanomaterials against corrosion and oxidation are investigated, highlighting their potential in mitigating material degradation. Furthermore, we delve into the nuanced interplay between mechanical and corrosive factors in the specific application of 2D materials for tribo-corrosion and -oxidation protection. The synthesis of key findings underscores the advancements achieved through integrating 2D nanomaterials. An outlook for future research directions is provided, identifying unexplored avenues, and proposing strategies to propel the field forward. This analysis aims at guiding future investigations and developments at the dynamic intersection of 2D nanomaterials, tribo-corrosion, and -oxidation protection.

2D Nanomaterials Reinforced Organic Coatings for Marine Corrosion Protection: State of the Art, Challenges, and Future Prospectives

2D nanomaterials, with extraordinary physical and chemical characteristics, have long been regarded as promising nanofillers in organic coatings for marine corrosion protection. The past decade has witnessed the high-speed progress of 2D nanomaterial-reinforced organic composite coatings, and plenty of breakthroughs have been achieved as yet. This review covers an in-depth and all-around outline of the up-to-date advances in 2D nanomaterial-modified organic coatings employed for the marine corrosion protection realm. Starting from a brief introduction to 2D nanomaterials, the preparation strategies and properties are illustrated. Subsequently, diverse protection models based on composite coatings for marine corrosion protection are also introduced, including physical barrier, self-healing, as well as cathodic protection, respectively. Furthermore, computational simulations and critical factors on the corrosion protection properties of composite coatings are clarified in detail. Finally, the remaining challenges and prospects for marine corrosion protection based on 2D nanomaterials reinforced organic coatings are highlighted.

Bio-inspired Ti3C2Tx MXene composite coating for enhancing corrosion resistance of aluminum alloy in acidic environments

Aluminum alloy (Al alloy) suffers from severe corrosion in acidic solution. Two-dimensional (2D) MXene-based composite coatings show great prospects for corrosion protection on metals used in special conditions. The composite coatings still face challenges in complex functionalization and orientation control. In harsh conditions, the long-term ability and roles of MXene in corrosion protection are still not clear. Here, a bio-inspired myristic-calcium chloride-Ti3C2Tx MXene (MA + CaCl2 + MXene) composite coating is successfully prepared on aluminum alloy (Al alloy) by electrodeposition process. Electrochemical tests, surface morphology, and chemical composition are analyzed to investigate the corrosion resistance and protection mechanism of the MXene coating in acidic solution (0.5 M H2SO4 + 2 ppm HF). As a result, the incorporation of MXene can significantly reduce corrosion current density (7.498 × 10-8 A/cm2) by ∼ 5 orders of magnitude and impedance modulus at 0.01 Hz (|Z|0.01 Hz) value of the composite coating is 196.8 Ω·cm2, which is over 4 times higher than that of bare Al alloy (40.74 Ω·cm2) after immersion test for 72 h. Furthermore, the in-situ corrosion test confirms the enhanced corrosion resistance of the MA + CaCl2 + MXene composite coating. The MXene can increase coating thickness to 23.6 ± 0.4 μm, reduce porosity to (5.845 ± 1) × 10-5, decrease the diffusion coefficients of H+ to (1.587 ± 0.3) × 10-9 cm2/s, and enhance the adhesion of the coating to the substrate (the delamination time exceeds 5 h), thus providing improved anti-corrosion ability. This strategy opens up new prospects for construction of 2D MXene-based anti-corrosion coatings.

Advanced materials for smart protective coatings: Unleashing the potential of metal/covalent organic frameworks, 2D nanomaterials and carbonaceous structures

The detrimental impact of corrosion on metallic materials remains a pressing concern across industries. Recently, intelligent anti-corrosive coatings for safeguarding metal infrastructures have garnered significant interest. These coatings are equipped with micro/nano carriers that store corrosion inhibitors and release them when triggered by external stimuli. These advanced coatings have the capability to elevate the electrochemical impedance values of steel by 2-3 orders of magnitude compared to the blank coating. However, achieving intelligent, durable, and reliable anti-corrosive coatings requires careful consideration in the design of these micro/nano carriers. This review paper primarily focuses on investigating the corrosion inhibition mechanism of various nano/micro carriers/barriers and identifying the challenges associated with using them for achieving desired properties in anti-corrosive coatings. Furthermore, the fundamental aspects required for nano/micro carriers, including compatibility with the coating matrix, high specific surface area, stability in different environments, stimuli-responsive behavior, and facile synthesis were investigated. To achieve this aim, we explored the properties of micro/nanocarriers based on oxide nanoparticles, carbonaceous and two-dimensional (2D) nanomaterials. Finally, we reviewed recent literature on the application of state-of the art nanocarriers based on metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs). We believe that the outcomes of this review paper offer valuable insights for researchers in selecting appropriate materials that can effectively enhance the corrosion resistance of coatings.

Prospective applications of two-dimensional materials beyond laboratory frontiers: A review

The development of nanotechnology has been advancing for decades and gained acceleration in the 21st century. Two-dimensional (2D) materials are widely available, giving them a wide range of material platforms for technological study and the advancement of atomic-level applications. The design and application of 2D materials are discussed in this review. In order to evaluate the performance of 2D materials, which might lead to greater applications benefiting the electrical and electronics sectors as well as society, the future paradigm of 2D materials needs to be visualized. The development of 2D hybrid materials with better characteristics that will help industry and society at large is anticipated to result from intensive research in 2D materials. This enhanced evaluation might open new opportunities for the synthesis of 2D materials and the creation of devices that are more effective than traditional ones in various sectors of application.

Sulfonated Polyaniline-Grafted Two-Dimensional Ti3C2-MXene (SPANI-MXene) Nanoplatform for Designing an Advanced Smart Self-Healable Coating System

MXene nanosheets (MXenes), a brand-new classification of two-dimensional (2D) nanomaterials, are assumed to be highly functional components in anticorrosion polymeric systems. In general, MXenes possess many advantageous features that can be utilized to improve the polymeric matrices' anticorrosion performance. In this work, zinc ions (Zn) were deposited on the sulfonated polyaniline (SPANI) that was polymerized on Ti₃C₂-MXene surfaces (MXP-Zn) in order to achieve a high-performance anticorrosion nanofiller for epoxy coating (EP-MXP-Zn). Field-emission scanning electron microscopy-transmission electron microscopy images, Fourier transform infrared, Raman, X-ray diffraction, UV-vis, derivative thermogravimetry, and thermogravimetric analysis have evidenced the successful characterization of the MXP-Zn nanocomposite. Likewise, the excellent barrier properties of SPANI, in conjunction with the cathodic protection of Zn, resulted in a novel nanocomposite that could mitigate the negative consequences of destructive ions' attack on the metal surface in an aggressive media. Quantitative and qualitative anticorrosion measurements verified the outstanding anticorrosion performance of EP-MXP-Zn over time in severe conditions. According to the electrochemical impedance spectroscopy assessments, the |Z_0.01 Hz| value for EP-MXP-Zn was 10^10.04 Ω cm², which was over 10⁵ times greater than that of neat EP (10^4.66 Ω cm²) over a 6-week period of immersion in a 3.5 wt % NaCl solution.