Abstract:Silicon carbide (SiC) aerogels are promising thermal insulators that are lightweight and possess high thermal stability. However, their application is hindered by their brittleness. Herein, an air suction effect induction (ASEI) strategy is proposed to fabricate a super thermally insulating SiC aerogel (STISA). The ASEI strategy exploits the air suction effect to subtly regulate the directional flow of the SiO gas, which can induce directional growth and assembly of SiC nanowires to form a directional lamellar… Show more
“…The sample showed a compressive strength of 0.0761 MPa and a Young’s modulus of 3.52 MPa, with a satisfying ductility strain of 9.34%. The unit rupture work of R-TiO 2 /ZnWO 4 in compression was as high as 3100 J m −3 g −1 , outperforming previously reported advanced ceramic materials 32 – 34 . Fig.…”
Photoelectrochemical device is a versatile platform for achieving various chemical transformations with solar energy. However, a grand challenge, originating from mass and electron transfer of triphase—reagents/products in gas phase, water/electrolyte/products in liquid phase and catalyst/photoelectrode in solid phase, largely limits its practical application. Here, we report the simulation-guided development of hierarchical triphase diffusion photoelectrodes, to improve mass transfer and ensure electron transfer for photoelectrochemical gas/liquid flow conversion. Semiconductor nanocrystals are controllably integrated within electrospun nanofiber-derived mat, overcoming inherent brittleness of semiconductors. The mechanically strong skeleton of free-standing mat, together with satisfactory photon absorption, electrical conductivity and hierarchical pores, enables the design of triphase diffusion photoelectrodes. Such a design allows photoelectrochemical gas/liquid conversion to be performed continuously in a flow cell. As a proof of concept, 16.6- and 4.0-fold enhancements are achieved for the production rate and product selectivity of methane conversion, respectively, with remarkable durability.
“…The sample showed a compressive strength of 0.0761 MPa and a Young’s modulus of 3.52 MPa, with a satisfying ductility strain of 9.34%. The unit rupture work of R-TiO 2 /ZnWO 4 in compression was as high as 3100 J m −3 g −1 , outperforming previously reported advanced ceramic materials 32 – 34 . Fig.…”
Photoelectrochemical device is a versatile platform for achieving various chemical transformations with solar energy. However, a grand challenge, originating from mass and electron transfer of triphase—reagents/products in gas phase, water/electrolyte/products in liquid phase and catalyst/photoelectrode in solid phase, largely limits its practical application. Here, we report the simulation-guided development of hierarchical triphase diffusion photoelectrodes, to improve mass transfer and ensure electron transfer for photoelectrochemical gas/liquid flow conversion. Semiconductor nanocrystals are controllably integrated within electrospun nanofiber-derived mat, overcoming inherent brittleness of semiconductors. The mechanically strong skeleton of free-standing mat, together with satisfactory photon absorption, electrical conductivity and hierarchical pores, enables the design of triphase diffusion photoelectrodes. Such a design allows photoelectrochemical gas/liquid conversion to be performed continuously in a flow cell. As a proof of concept, 16.6- and 4.0-fold enhancements are achieved for the production rate and product selectivity of methane conversion, respectively, with remarkable durability.
“…Moreover, the oriented layered SiC aerogel showed excellent large strain elasticity (60%) and fatigue resistance for 10 000 compressions (Figure 11a). [64] Wan et al introduced directional 2D graphene into 3D ceramic substrates (alumina, silicon oxide, zirconia, etc.) to transform the catastrophic fracture failure mode of brittle ceramics into a stable crack propagation behavior, improving the mechanical toughness by 250-500% (Figure 11b).…”
Advanced ceramic materials and devices call for better reliability and damage tolerance. In addition to their strong bonding nature, there are examples demonstrating superior mechanical properties of nanostructure ceramics, such as damage‐tolerant ceramic aerogels that can withstand high deformation without cracking and local plasticity in dense nanocrystalline ceramics. The recent progresses shall be reviewed in this perspective article. Three topics including highly elastic nano‐fibrous ceramic aerogels, load‐bearing nanoceramics with improved mechanical properties, and implementing machine learning‐assisted simulations toolbox in understanding the relationship among structure, deformation mechanisms, and microstructure‐properties shall be discussed. It is hoped that the perspectives present here can help the discovery, synthesis, and processing of future structural ceramic materials that are insensitive to processing flaws and local damages in service.
“…Aerogels are a kind of ultralight materials with many unusual performances including high porosity, high specific surface area, low thermal conductivity, and high adsorption ability owing to their unique nanoporous structure. − Additionally, they have attracted considerable attention in the fields of supporters, adsorption, superthermal insulation, , acoustic insulation, separation, and so on. Based on the different compositions, aerogels can be basically divided into oxide aerogels, organic aerogels, carbon aerogels, ceramic aerogels, metal aerogels, , and other hybrid aerogels .…”
Silica aerogels have already been recognized as potential candidates in the fields of thermal insulation, sorption, and separation, but the intrinsic brittleness and cumbersome preparation process limit their broad applications. In this work, a simple self-catalyzed gelling strategy was applied to prepare organic−inorganic in situ hybrid aerogels (OIHAs) derived from bis [3-(triethoxysilyl)propyl]amine (BTPA) and methyltrimethoxysilane (MTES). The Si−CH 3 groups from MTES make it possible for OIHAs to be prepared through ambient drying and exhibit good hydrophobicity. Owing to the alkalinity of the amine groups from BTPA, self-catalyed hydrolyzation and condensation reactions occur between two silicon precursors to build a uniform pearl-chain nanoporous structure. The high specific surface area and amine groups existing on the nanoskeleton surface of the obtained OIHAs endow them with fascinating CO 2 capture ability up to 5.89 mmol/g at 298 K and 100 kPa, which are significantly higher than the values of other aerogels reported under the similar conditions. Furthermore, ultralow thermal conductivity (as low as 20.1 mW/(m•K) at 25 °C), high strength (up to 2.38 MPa), and great elasticity (fully recoverable elastic strain of 14%) are achieved together for the OIHAs due to the organic−inorganic in situ cross-linked architecture. The as-prepared OIHAs with versatile properties have great application prospects in the fields of building thermal insulation and CO 2 capture. The self-catalyzed gelling strategy provides an alternative routine for the simple preparation of silica-based aerogels.
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