Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
Sci Adv. 2023 May 10;9(19):eadf9931. doi: 10.1126/sciadv.adf9931.
High-entropy alloy (HEA) nanocrystals have attracted extensive attention in catalysis. However, there are no effective strategies for synthesizing them in a controllable and predictable manner. With quinary HEA nanocrystals made of platinum-group metals as an example, we demonstrate that their structures with spatial compositions can be predicted by quantitatively knowing the reduction kinetics of metal precursors and entropy of mixing in the nanocrystals under dropwise addition of the mixing five-metal precursor solution. The time to reach a steady state for each precursor plays a pivotal role in determining the structures of HEA nanocrystals with homogeneous alloy and core-shell features. Compared to the commercial platinum/carbon and phase-separated counterparts, the dendritic HEA nanocrystals with a defect-rich surface show substantial enhancement in catalytic activity and durability toward both hydrogen evolution and oxidation. This quantitative study will lead to a paradigm shift in the design of HEA nanocrystals, pushing away from the trial-and-error approach.
高熵合金（HEA）纳米晶体在催化领域引起了广泛关注。然而，目前还没有有效的方法可以对其进行可控和可预测的合成。本文以五元铂族金属 HEA 纳米晶体为例，证明了通过定量了解金属前驱体的还原动力学和纳米晶体中混合熵，在逐滴添加混合五金属前驱体溶液的情况下，可以预测其具有空间组成的结构。对于每个前驱体达到稳定状态的时间，在确定具有均匀合金和核壳特征的 HEA 纳米晶体结构方面起着关键作用。与商业的铂/碳和相分离对应物相比，具有缺陷丰富表面的枝晶 HEA 纳米晶体在析氢和氧化反应的催化活性和耐久性方面都有显著提高。这项定量研究将推动 HEA 纳米晶体的设计范式发生转变，从试错法转变为定量预测法。
