Xiaobo Zhu,Qingqing Yan,Li Cheng,Hao Wu,Haichao Zhao,Liping Wang
Designing coatings with long term anticorrosion performance remains a great challenge. Herein, a newfangled cationic dopamine-reduced graphene oxide (DRGO + ) nanosheet is prepared as a filler for epoxy coating via simple dopamine oxidative self-polymerization and ionization reaction. DRGO + can be dispersed stably in commercial water-based cathodic epoxy emulsion for more than 45 days without precipitation. Due to the presence of –NH 3 + in DRGO + , it can be self-aligned parallel arrangement in the composite coating (DRGO + /EP coating) under the electric field. This highly parallel DRGO + nanosheets tremendously improve the physical barrier effect of the coating and prolong the penetration path of the corrosive medium. Electrochemical impedance spectroscopy (EIS) test showed that the initial low-frequency impedance modulus of 0.5%-DRGO + /EP coating is as high as 4.79 × 10 10 Ω cm 2 when the content of DRGO + is 0.5 wt%, which is an order of magnitude higher than that of pure epoxy coating (4.07 × 10 9 Ω cm 2 ), exhibiting extraordinary corrosion resistance. Finally, the protective mechanism of composite coating is revealed by the identification of corrosion products and local-EIS techniques. In view of the validity of DRGO + , this work highlights the potential route for the large-scale preparation of coatings with superior long-term anti-corrosion.
Jianglei Zhang,Yifan Yang,Weijun Li,Zigao Tang,Zhiying Hu,Haotong Wei,Junhu Zhang,Bai Yang
Patterned arrays of perovskite single crystals can avoid signal cross-talk in optoelectronic devices, while precise crystal distribution plays a crucial role in enhancing device performance and uniformity, optimizing photoelectric characteristics, and improving optical management. Here, we report a strategy of droplet-assisted self-alignment to precisely assemble the perovskite single-crystal arrays (PSCAs). High-quality single-crystal arrays of hybrid methylammonium lead bromide (MAPbBr3) and methylammonium lead chloride (MAPbCl3), and cesium lead bromide (CsPbBr3) can be precipitated under a formic acid vapor environment. The crystals floated within the suspended droplets undergo movement and rotation for precise alignment. The strategy allows us to deposit PSCAs with a pixel size range from 200 to 500 micrometers on diverse substrates, including indium tin oxide, glass, quartz, and poly(dimethylsiloxane), and the area can reach up to 10 centimeters by 10 centimeters. The PSCAs exhibit excellent photodetector performance with a large responsivity of 24 amperes per watt.
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