The properties of polycrystalline materials are often dominated by defects; two-dimensional (2D) crystals can even be divided and disrupted by a line defect. However, 2D crystals are often required to be processed into films, which are inevitably polycrystalline and contain numerous grain boundaries, and therefore are brittle and fragile, hindering application in flexible electronics, optoelectronics and separation. Moreover, similar to glass, wood and plastics, they suffer from trade-off effects between mechanical strength and toughness. Here we report a method to produce highly strong, tough and elastic films of an emerging class of 2D crystals: 2D covalent organic frameworks (COFs) composed of single-crystal domains connected by an interwoven grain boundary on water surface using an aliphatic bi-amine as a sacrificial go-between. Films of two 2D COFs have been demonstrated, which show Young's moduli and breaking strengths of 56.7 ± 7.4 GPa and 73.4 ± 11.6 GPa, and 82.2 ± 9.1 N m and 29.5 ± 7.2 N m, respectively. We predict that the sacrificial go-between guided synthesis method and the interwoven grain boundary will inspire grain boundary engineering of various polycrystalline materials, endowing them with new properties, enhancing their current applications and paving the way for new applications.
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http://dx.doi.org/10.1038/s41586-024-07505-x | DOI Listing |
Science
January 2025
Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA.
Accurately modeling the deformation of temperate glacier ice, which is at its pressure-melting temperature and contains liquid water at grain boundaries, is essential for predicting ice sheet discharge to the ocean and associated sea-level rise. Central to such modeling is Glen's flow law, in which strain rate depends on stress raised to a power of = 3 to 4. In sharp contrast to this nonlinearity, we found by conducting large-scale, shear-deformation experiments that temperate ice is linear-viscous ( 1.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Key Lab for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, School of Nanoscience and Materials Engineering, Collaborative Innovation Center of Nano Functional Materials and Applications, Henan University, Kaifeng, 475004, P. R. China.
Flexible perovskite solar cells (FPSCs) are a promising emerging photovoltaic technology, with certified power conversion efficiencies reaching 24.9 %. However, the frequent occurrence of grain fractures and interface delamination raises concerns about their ability to endure the mechanical stresses caused by temperature fluctuations.
View Article and Find Full Text PDFNature
January 2025
Department of Materials Engineering, Indian Institute of Science, Bangalore, India.
Piezoelectric materials directly convert between electrical and mechanical energies. They are used as transducers in applications such as nano-positioning and ultrasound imaging. Improving the properties of these devices requires piezoelectric materials capable of delivering a large longitudinal strain on the application of an electric field.
View Article and Find Full Text PDFJ Colloid Interface Sci
January 2025
College of Energy Engineering, Huanghuai University, Zhumadian 463000, China. Electronic address:
Herein, a novel liquid nitrogen quenching treatment is proposed to achieve multifaceted modulation involving morphological modulation, lattice tensile strain modulation, metal active centre coordination reconstruction and grain boundary construction within a series of intermetallic compounds modified on a carbon substrate (CoFe-550/C, CoNi-550/C and FeNi-550/C, where 550 refers to liquid nitrogen quenching temperature and C refers to the carbon substrate). Noteworthily, the optimising intermediate absorption/desorption process is achieved by multifaceted modulation. Consequently, CoFe-550/C, CoNi-550/C and FeNi-550/C demonstrate considerable overpotential for hydrogen evolution reaction (59.
View Article and Find Full Text PDFPLoS One
January 2025
Department of Physics, Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh.
High dielectric constants with less dielectric loss composites is highly demandable for technological advancements across various fields, including energy storage, sensing, and telecommunications. Their significance lies in their ability to enhance the performance and efficiency of a wide range of devices and systems. In this work, the dielectric performance of graphene oxide (GO) reinforced plasticized starch (PS) nanocomposites (PS/GO) for different concentrations of GO nanofiller was studied.
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