Synthesis of Ultrathin Functional Boron Nitride Nanosheets and Their Application in Anticorrosion

Abstract

Hexagonal boron nitride (hBN) shows huge promise for metallic corrosion protection due to its excellent impermeability. However, the exfoliation and dispersion of hBN have proven to be very challenging, owing to the strong "lip−lip" interactions and inherent hydrophobic features. Herein, ultrathin IL-BN nanosheets were synthesized and simultaneously noncovalent functionalized by ionic liquid (IL) through a liquid ball milling strategy to achieve the good compatibility with epoxy (EP), which was characterized by scanning electron microscope (SEM), transmittance electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectronic spectroscopy (XPS), and UV−vis absorbance spectroscopy. Electrochemical measurements confirmed that the addition of 0.5 wt % IL-BN into the EP matrix significantly enhanced the anticorrosion capability of coatings. After 4 weeks of immersion in 3.5 wt % NaCl solution, the IL-BN-EP coating remained with a high coating resistance R c of 5.6 × 10 9 Ω cm 2 , 4 orders of magnitude higher than EP (4.9 × 10 5 Ω cm 2 ). SEM and Raman measurements also corroborated that the steel protected by IL-BN-EP was hardly corroded. Moreover, the passivation effect of IL-BN-EP coating was confirmed by potential polarization curve (PPC) tests at the coating defects. The superior anticorrosion performance of IL-BN-EP coating was mainly attributed to the synergistic effect of physical barrier and self-healing property endowed by the well-dispersed IL-BN hybrids.

Probing the Mechanically Stable Solid Electrolyte Interphase and the Implications in Design Strategies

“…We summarize the SEI thickness values evaluated from different techniques in Figure 6f. [ 9b,10a,26,27,29,31e,g,j,39a,40,42,65b,66b,69l,81,82,83a,c,91b,101,103,104 ] We note there could be large differences in the thickness determined by the F – d curve and cryo‐TEM, and usually the value obtained in the former is larger. In addition to the intrinsic differences of tested systems, the difference in mean values may also be influenced by the lower resolution of the F – d curves.…”

“…Using this method to determine the thickness of each layer of a multilayer SEI heightens this uncertainty even more. Another important category for determining SEI thickness is from various microscopy images, including cryo‐TEM, [ 31j,81,83c,101,103 ] SEM, [ 47,96a ] and optical images. [ 83b ] Issues to consider when using these methods are whether the magnification and resolution of the images are sufficiently high and the possible effects of electron radiation on SEI.…”

“…As we mentioned earlier, sometimes it is hard to decide whether Young's modulus or elastic strain limit plays a more important role in deciding the mechanical performance of SEI, the maximum elastic deformation energy ( U ) is proved to be a better indicator of the mechanical stability of SEI in various metal and metal‐ion batteries. [ 10,81,83c,d,103a ] U can reflect the combined effect of E and ε Y . The magnitude of U corresponds to the area under the force–displacement curve up to the elastic limit $$\[U = \mathop \smallint \limits_0^{{d_{\rm{c}}}} Fd\left( d \right)\]$$…”

Emerging Layered Materials and Their Applications in the Corrosion Protection of Metals and Alloys

“…Again, this good dispersion was attributed to strong π-π interactions between h-BN and the trimer. Poly(2-butyl aniline) (PBA) [58] and furfuryl methacrylate [179] have also been employed to give well-dispersed h-BN in epoxy coatings, while ionic liquids, with their conjugated structures and nitrogen atoms, facilitate π-π interactions with the h-BN nanoplatelets [180]. In addition, GO, with hydrophilic characteristics, was employed as an intercalator to exfoliated h-BN and enhanced its dispersion.…”

“…This relatively simple method was reported to provide good compatibility between the h-BN and the epoxy matrix, resulting in impressive corrosion-protective performance. These non-covalent and covalent modifications of h-BN enhance its dispersion in epoxy [58,178,180,181,183,185,187] and acrylic [186] coatings, giving rise to good corrosion-protective properties. The enhanced anticorrosive performance has normally been attributed to the homogeneously dispersed h-BN nanoplatelets, which provide very good water-and oxygen-barrier properties.…”