Beating Thermal Coarsening in Nanoporous Materials via High-Entropy Design
Beating Thermal Coarsening in Nanoporous Materials via High-Entropy Design
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DOI：
10.1002/adma.201906160
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发表时间：
2019-12-04
影响因子：
29.4
通讯作者：
Okulov, Ilya, V
中科院分区：
文献类型：
--
作者：
Joo, Soo-Hyun;Bae, Jae Wung;Okulov, Ilya, V
控制3D双连续纳米多孔（3DNP）材料的特征尺寸对于它们在催化、传感、能源系统等中的高级应用是必不可少的，需要高的比表面积。然而，纳米多孔材料的固有粗化自然降低了它们的表面能，导致物理性质随时间的劣化，即使在环境温度下也是如此。通过高熵合金（HEA）设计，报道了一种新型的3DNP材料，该材料克服了热粗化的普遍关系。在新开发的TiVNbMoTa 3DNP HEAs中，由于通过最大化配置熵和抑制表面扩散来增强相稳定性，纳米多孔结构由固溶体相的非常精细的纳米级韧带构造。在873 K下合成的3DNP HEA的最小尺寸约为10 nm，比常规多孔材料的最小尺寸小一个数量级。更重要的是，即使在热暴露之后，3DNP HEA中的韧带的屈服强度也接近其相应HEA合金的理论强度G/2 pi。这一发现表明了高熵设计在纳米多孔材料中的关键优势-尺寸相关物理性质的异常稳定性。因此，这种高熵策略应该为开发针对其环境的超稳定纳米材料提供新的机会。
Controlling the feature sizes of 3D bicontinuous nanoporous (3DNP) materials is essential for their advanced applications in catalysis, sensing, energy systems, etc., requiring high specific surface area. However, the intrinsic coarsening of nanoporous materials naturally reduces their surface energy leading to the deterioration of physical properties over time, even at ambient temperatures. A novel 3DNP material beating the universal relationship of thermal coarsening is reported via high-entropy alloy (HEA) design. In newly developed TiVNbMoTa 3DNP HEAs, the nanoporous structure is constructed by very fine nanoscale ligaments of a solid-solution phase due to enhanced phase stability by maximizing the configuration entropy and suppressed surface diffusion. The smallest size of 3DNP HEA synthesized at 873 K is about 10 nm, which is one order of magnitude smaller than that of conventional porous materials. More importantly, the yield strength of ligament in 3DNP HEA approaches its theoretical strength of G/2 pi of the corresponding HEA alloy even after thermal exposure. This finding signifies the key benefit of high-entropy design in nanoporous materials-exceptional stability of size-related physical properties. This high-entropy strategy should thus open new opportunities for developing ultrastable nanomaterials against its environment.