The wide application of Mg Li alloys is limited by the poor corrosion resistance , which needs to be improved by surface treatment. Plasma electrolytic oxidation (PEO) method is one of the most promising methods for the formation of oxide coatings on Mg Li alloys. However, the conventional PEO technique with high energy consumption causes poor coating compactness and hampers efforts to enhance corrosion resistance . In this study, various concentrations of ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, BmimBF 4 ) are introduced into the concentrated alkaline electrolyte to facilitate the formation of a PEO coating on the surface of LA91 magnesium‑lithium (Mg Li) alloy. The influence of BmimBF 4 on PEO coatings has been investigated. The results indicate that a concentrated electrolyte significantly lowers the working voltage of PEO, thereby enhancing energy efficiency. Uneven adsorption on the substrate surface, resulting from the low concentration of BmimBF 4 (≤20 mL/L) in the electrolyte, induces partial discharge, leading to high surface roughness and the formation of large pores. However, when an excessive amount of BmimBF 4 (>20 mL/L) is present, it uniformly adsorbed onto the substrate surface during the initial stage of PEO process, forming a corrosion inhibitor layer. This leads to a consistent discharge on the surface of substrate throughout the entire PEO process, resulting in a reduction in both surface roughness and micropore size. Among these coatings, the one prepared in an electrolyte containing 20 mL/L BmimBF 4 exhibits the highest contact angle (66.8° ± 3.8°) and the best long-term corrosion resistance (hydrogen evolution rates <0.02 mL·cm −2 ·h −1 ). These properties can be attributed to the physical and chemical adsorption of BmimBF 4 , which contains hydrophobic long alkyl chains, as well as the maximum thickness with extended discharging channels. This study offers a guiding strategy for further reducing energy consumption and enhancing the corrosion resistance of PEO coatings.
Weifeng Ma,Chunjie Ding,Nasrullah Wazir,Xianshuang Wang,Denan Kong,An Li,Bingsuo Zou,Ruibin Liu
The methylammonium lead triiodide (CH3NH3PbI3)-based perovskite shows a great alluring prospect in areas of solar cells, lasers, photodetectors, and light emitting diodes owing to their excellent optical and electrical advantages. However, it is very sensitive to the surrounding oxygen and moisture, which limits its development seriously. It is urgent to spare no effort to enhance its optical and electrical stability for further application. In this paper, we synthesize the MAPbI3 perovskite film on the glass substrate with/without the ionic liquid (IL) of 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) by a simple two-step sequential solution method. The additive of BMIMBF4 can improve the quality of crystal structure. Moreover, the photo-luminescence (PL) intensity of MAPbI3 film with BMIMBF4 is much stronger than the pure MAPbI3 film after a week in the air, which is almost ten-fold of the pure one. Meanwhile, under the illumination of 405-nm continuous wave (CW) laser, the fluorescent duration of the MAPbI3 film with BMIMBF4 is approximately 2.75 min, while the pure MAPbI3 film is only about 6 s. In fact, ionic liquid of BMIMBF4 in the perovskite film plays a role of passivation, which prevents the dissolution of MAPbI3 into CH3NH3 and PbI2 and thus enhances the stability of environment. In addition, the ionic liquid of BMIMBF4 possesses high ionic conductivity, which accelerates the electron transport, so it is beneficial for the perovskite film in the areas of solar cells, photodetectors, and lasers. This interesting experiment provides a promising way to develop the perovskite's further application.
危险品化学品经营许可证（带存储）