J Am Chem Soc. 2020 Aug 5;142(31):13345-13349. doi: 10.1021/jacs.0c06602. Epub 2020 Jul 28.
Cation exchange reactions of colloidal copper sulfide nanoparticles are widely used to produce derivative nanoparticles having unique compositions, metastable crystal structures, and complex heterostructures. The copper sulfide crystal structure plays a key role in the mechanism by which cation exchange occurs and the product that forms. Here, we show that digenite copper sulfide nanoparticles undergo a spontaneous phase transition to tetragonal chalcocite , prior to the onset of cation exchange. Room-temperature sonication of digenite (CuS) in trioctylphosphine, a Lewis base that drives cation exchange, extracts sulfur to produce tetragonal chalcocite (CuS). The subtle structural differences between digenite and tetragonal chalcocite are believed to influence the accessibility of cation diffusion channels and concomitantly the mechanism of cation exchange. Structural relationships in nanocrystal cation exchange are therefore dynamic, and intermediates generated must be considered.
胶体硫化铜纳米粒子的阳离子交换反应被广泛用于生产具有独特成分、亚稳晶体结构和复杂异质结构的衍生纳米粒子。硫化铜晶体结构在阳离子交换发生的机制和形成的产物中起着关键作用。在这里，我们表明，在阳离子交换开始之前，辉铜矿纳米粒子会自发地发生从斜方辉铜矿到四方蓝铜矿的相变。在三辛基膦中对辉铜矿（CuS）进行室温超声处理，三辛基膦是一种引发阳离子交换的路易斯碱，会提取硫来生成四方蓝铜矿（CuS）。人们认为，辉铜矿和四方蓝铜矿之间的细微结构差异会影响阳离子扩散通道的可及性，并相应地影响阳离子交换的机制。因此，纳米晶阳离子交换中的结构关系是动态的，必须考虑所生成的中间产物。
