Assembly of lightweight engineering and functional materials with superb mechanical performance, such as high stiffness, super resilience, and stability, is highly demanded to pave ways for their practical applications. [1] However, how to simultaneously achieve both stiffness and resilience in a man-made material at low-density remains a challenging scientific and engineering issue. Biological materials have found their way to achieve outstanding mechanical properties at low density by assembling sophisticate hierarchical structures from microscopic to macroscopic scales, and thus provide inspirations for designing and manufacturing advanced biomimetic materials. [2] Plant materials, such as plant stem [3] and wood, [4] represent an important class of lightweight natural materials with superb mechanical properties. The slender grass stems of Elytrigia repens is a representative natural material with high mechanical performance and lightweight features owing to a specially evolved hierarchical architecture with a macroscopically hollow and microscopically cellular structure. The macroscopically hollow structure combined with the cellular microstructure serves as an excellent force-bearing structure that is conducive to the dispersion of strain and stress, and thus efficiently enhances the stiffness, and resilience and reduce the density, simultaneously. [5] In recent years, the constructions of biomimetic structures have attracted extensive attention because of their potential ability to achieve high mechanical properties and lightweight artificial engineering and functional materials. [6] Despite progresses in the construction of biomimetic structures, the poor mechanical properties at low density remain as a major bottleneck in artificial biomimetic materials, which are mainly due to the lack of appropriate structures at both macro-and microlevels at the same time.The ink-based 3D printing, as a powerful additive manufacturing technique for producing 3D structures both in microscopic and macroscopic scales, [6b,7] shows great potential to assembly materials into 3D hierarchical structures. Additionally, 3D printing displays distinct advantages of high degree of freedom in structure design, which enable the ability to design and construct versatile structures for realizing the Biological materials with hierarchical architectures (e.g., a macroscopic hollow structure and a microscopic cellular structure) offer unique inspiration for designing and manufacturing advanced biomimetic materials with outstanding mechanical performance and low density. Most conventional biomimetic materials only benefit from bioinspired architecture at a single length scale (e.g., microscopic material structure), which largely limits the mechanical performance of the resulting materials. There exists great potential to maxime the mechanical performance of biomimetic materials by leveraging a bioinspired hierarchical structure. An ink-based three-dimensional (3D) printing strategy to manufacture an ultralight biomimetic hierarchical g...
The morphology of Pt−Au bimetal nanostructures plays an important role in enhancing the catalytic capability, catalytic stability and utilization efficiency of the platinum. We designed and successfully prepared Au@Pt nanoparticles (NPs) through an economical, surfactant-free and efficient method of seed-mediated growth. The Au@Pt NPs displayed electrochemical performances superior to those of commercial Pt/C catalysts because their agglomeration was prevented and exhibited better long-term stability with respect to methanol oxidation in acidic media by efficiently removing intermediates. Among the obtained Au@Pt NPs, Au90@Pt10 NPs exhibited the most significantly enhanced catalytic performance for the methanol oxidation reaction (MOR). Their mass and electrochemically active surface area (ECSA)-normalized current densities are approximately 3.9 and 4.6 times higher than those of commercial Pt/C catalysts, respectively. The oxidation current densities of the Au90@Pt10 NPs are approximately 1.8 times higher than those of commercial Pt/C catalysts after 4000 s of continuous measurement because the small Pt NPs grown on the surface of the Au90@Pt10 NPs were effectively stabilized by the Au metal support. This approach may be a facile method for the synthesis of self-supported bimetallic nanostructures, which is of great significance for the development of high performance electrocatalysts and sensors.
The direct formic acid fuel cell (DFAFC), with its high energy conversion efficiency, high energy density, rapid startup at room temperature, and other excellent features, is considered one of the most promising sources of green energy. Here, corallike PdCu bimetallic nanoparticles with large surface areas were successfully designed and fabricated via a simple approach and were used as an efficient electrocatalyst for formic acid oxidation (FAO). Introduction of Cu atoms into coral-like PdCu bimetallic nanoparticles not only affects the d-band centers of active sites by enhancing the catalytic performance but can also adjust the morphology to provide increased specific surface area. In addition, the electrocatalytic activity of the obtained PdCu/C was well optimized in FAO by tuning the composition of the metallic elements and the ratio of catalyst supports. The optimal electrocatalyst has an electrochemically active area of 36.34 m 2 g −1 and a mass activity of 1.05 A g Pd −1 , which are approximately 2 and 3.5 times higher than the values from commercial Pd/C, respectively. Most importantly, the chronoamperometry curve remained above 60% after 400 s, which is dramatically increased compared with Pd/C (<2.5%), illustrating the high stability of the PdCu bimetallic nanoparticle catalyst.
Methanol is extremely harmful to human health, since it is oxidized slowly and can accumulate in the human body. Therefore, it is essential to develop a methanol gas sensing technology with high sensitivity and selectivity for use in environmental monitoring and healthcare. In this work, a simple and low‐cost sensor based on a Y2O3 multishelled hollow structure (YMSH) to selectively detect methanol with an ultrasensitive limit of detection (71 ppb) is developed. The unique multishelled hollow structure with a large surface area and exposed {222} facets makes an important contribution to the ultrasensitive detection of methanol, which is further confirmed by subsequent theoretical simulations. Moreover, in situ Fourier transform infrared spectra verify that CO2 is the final product, which indicates a high catalytic activity of the YMSHs toward methanol oxidation. Interestingly, the sensor can also be applied to liquor samples that are mixtures of ethanol, methanol, and water, which provides a facile way to detect methanol in wines. This sensor represents a unique and highly sensitive means to detect methanol, which has great promise for potential application in environmental monitoring and food safety inspection.
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