The high entropy alloy (HEA) possesses distinctive thermal stability and electronic characteristics, which exhibits substantial potential for diverse applications in electrocatalytic reactions. However, accurately controlling the size of HEA still remains a challenge, especially for the ultrasmall HEA nanoparticles. Herein, we firstly calculate and illustrate the size impact on the electronic structure of HEA and the adsorption energies of crucial intermediates in typical electrocatalytic reactions, such as the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), CO2 electroreduction (CO2RR) and NO3– electroreduction (NO3RR). Under the guidance of theoretical calculations, we synthesize a range of ultrasmall PtRuPdCoNi HEA nanoparticles with adjustable sizes (1.7, 2.3, 3.0, and 3.9 nm) using a one‐step spatially confined approach. Specifically, HEA nanoparticles with 1.7 nm size (HEA‐1.7) endows a 16 mV overpotential at current density of 10 mA cm−2, yielding a mass activity of 31.9 A mgNM‐1 of noble metal in HER, significantly outperforming commercial Pt/C catalyst. This strategy can also be easily applicable to other reduction reactions attributed to the richness of metal components and size adjustability, presenting a promising platform for various electrocatalytic applications as advanced catalysts.

中文翻译：

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尺寸可调的高熵合金纳米颗粒作为电催化的高效平台


高熵合金 （HEA） 具有独特的热稳定性和电子特性，在电催化反应中具有广阔的应用潜力。然而，准确控制 HEA 的大小仍然是一个挑战，尤其是对于超小的 HEA 纳米颗粒。在此，我们首先计算并说明了对高熵合金电子结构的尺寸影响以及典型电催化反应中关键中间体的吸附能，例如析氢反应 （HER）、氧还原反应 （ORR）、CO2 电还原 （CO2RR） 和 NO3– 电还原 （NO3RR）。在理论计算的指导下，我们使用一步空间限制方法合成了一系列尺寸可调（1.7、2.3、3.0 和 3.9 nm）的超小 PtRuPdCoNi HEA 纳米颗粒。具体来说，具有 1.7 nm 尺寸 （HEA-1.7） 的 HEA 纳米颗粒在 10 mA cm-2 的电流密度下产生 16 mV 的过电位，在 HER 中产生 31.9 A mgNM-1 的贵金属质量活性，明显优于商业 Pt/C 催化剂。由于金属组分的丰富性和尺寸可调性，该策略也可以很容易地应用于其他还原反应，为各种电催化应用作为高级催化剂提供了一个有前途的平台。