Tao Lu, Sun Mingzi, Zhou Yin, Luo Mingchuan, Lv Fan, Li Menggang, Zhang Qinghua, Gu Lin, Huang Bolong, Guo Shaojun
School of Materials Science and Engineering, Peking University, Beijing 100871, China.
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR China.
J Am Chem Soc. 2022 Jun 15;144(23):10582-10590. doi: 10.1021/jacs.2c03544. Epub 2022 Jun 2.
High-entropy alloys (HEAs) are attracting intensive attention due to their broad compositional tunability and interesting catalytic properties. However, precisely shaping the HEAs into suprathin low-dimensional nanostructures for achieving diverse applications remains an enormous challenge owing to their intrinsic thermodynamic instability. Herein we propose a new and general low-temperature method for incorporating up to eight metallic elements into one single-phase subnanometer ribbon to achieve the thinnest HEA metal materials in the world. We experimentally demonstrate that synthetic processes for suprathin HEA subnanometer ribbons (SNRs) include (1) different metal atom nucleation via galvanic exchange reaction between different metal precursors and Ag nanowire template, (2) co-reduction of different metal precursors on nanowire template, and (3) the removal of the inner Ag core. Density functional theory (DFT) calculations reveal that the crystallization and stabilization of HEA SNRs strongly depend on the "highly dynamic" Ag from the template, and the crystallization levels of HEA subnanometer ribbons are closely correlated with the concentration of Pt and Pd. We demonstrate that the present synthetic method enables the flexible control of components and concentrations in HEAs SNRs for achieving a library of HEA SNRs and also superior electrocatalytic properties. The well-designed HEA SNRs show great improvement in catalyzing the oxygen reduction reaction of fuel cells and also high discharge capacity, low charge overpotential, and excellent durability for Li-O batteries. DFT calculations reveal the superior electrochemical performances are attributed to the strong reduction capability from high-concentration reductive elements in HEAs, while the other elements guarantee the site-to-site efficient electron transfer.
高熵合金（HEAs）因其广泛的成分可调性和有趣的催化性能而备受关注。然而，由于其固有的热力学不稳定性，将高熵合金精确地加工成超薄低维纳米结构以实现各种应用仍然是一个巨大的挑战。在此，我们提出了一种新的通用低温方法，可将多达八种金属元素整合到单相亚纳米带中，以制备出世界上最薄的高熵合金金属材料。我们通过实验证明，超薄高熵合金亚纳米带（SNRs）的合成过程包括：（1）通过不同金属前驱体与银纳米线模板之间的电化交换反应实现不同金属原子的成核；（2）不同金属前驱体在纳米线模板上的共还原；（3）去除内部的银核。密度泛函理论（DFT）计算表明，高熵合金亚纳米带的结晶和稳定性强烈依赖于模板中“高度动态”的银，且高熵合金亚纳米带的结晶程度与铂和钯的浓度密切相关。我们证明，目前的合成方法能够灵活控制高熵合金亚纳米带中的成分和浓度，从而制备出一系列高熵合金亚纳米带，并具有优异的电催化性能。精心设计的高熵合金亚纳米带在催化燃料电池的氧还原反应方面有显著改善，同时在锂氧电池中也表现出高放电容量、低充电过电位和优异的耐久性。DFT计算表明，其优异的电化学性能归因于高熵合金中高浓度还原元素的强还原能力，而其他元素则保证了位点间高效的电子转移。
