Xu Xiang, Guo Yang, Bloom Brian P, Wei Jianjun, Li Haoyang, Li Hailong, Du Yankun, Zeng Zheng, Li Liqing, Waldeck David H
School of Energy Science and Engineering, Central South University, Changsha 410083, China.
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
ACS Nano. 2020 Dec 22;14(12):17704-17712. doi: 10.1021/acsnano.0c09470. Epub 2020 Dec 7.
High entropy alloy nanoparticles (HEA-NPs) are expanding their influence in many fields. To explore the electronic structures in such multielemental systems, HEA-NPs were synthesized on two different carbon substrates through carbothermal shock and reduction methods. The relationship between the apparent core level energy shifts (negative or positive) and the electron density changes among the components of quinary-metal HEA-NPs was investigated by X-ray photoelectron spectroscopy (XPS) analysis and first-principles electronic structure calculations. It was found that Cu displays a negative core level shift while Fe, Co, Mg, Cr, and Mn display a positive core level shift. While experiments show an apparent positive core level shift for Ni, electronic structure calculations reveal that this arises from shifts in the Fermi level and that the electron density redistribution in Ni behaves more like Cu than the other elements. The findings show that the electron density redistribution in the NPs occurs from less electronegative elements to more electronegative ones. This work should guide the design of HEA-NPs to expand their potential applications in mechanical structures, medicine, catalysis, and energy storage/conversion.
高熵合金纳米颗粒（HEA-NPs）正在许多领域扩大其影响力。为了探索此类多元素体系中的电子结构，通过碳热冲击和还原方法在两种不同的碳基底上合成了HEA-NPs。通过X射线光电子能谱（XPS）分析和第一性原理电子结构计算，研究了五元金属HEA-NPs各组分之间表观芯能级能量位移（负或正）与电子密度变化之间的关系。发现Cu显示出负的芯能级位移，而Fe、Co、Mg、Cr和Mn显示出正的芯能级位移。虽然实验表明Ni有明显的正芯能级位移，但电子结构计算表明，这是由费米能级的位移引起的，并且Ni中的电子密度重新分布的行为比其他元素更类似于Cu。研究结果表明，NPs中的电子密度重新分布是从电负性较小的元素向电负性较大的元素发生的。这项工作应指导HEA-NPs的设计，以扩大其在机械结构、医学、催化和能量存储/转换方面的潜在应用。
