Laboratory of Nanochemistry for Energy (LNCE), Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Sion CH-1950, Switzerland.
Institute of Chemical Science and Engineering (ISIC), École Polytechnique Fédérale de Lausanne, Sion CH-1950, Switzerland.
J Am Chem Soc. 2022 Oct 12;144(40):18286-18295. doi: 10.1021/jacs.2c05792. Epub 2022 Sep 29.
The compositional and structural diversity of bimetallic nanocrystals (NCs) provides a superior tunability of their physico-chemical properties, making them attractive for a variety of applications, including sensing and catalysis. Nevertheless, the manipulation of the properties-determining features of bimetallic NCs still remains a challenge, especially when moving away from noble metals. In this work, we explore the galvanic replacement reaction (GRR) of In NCs and a copper molecular precursor to obtain Cu-In bimetallic NCs with an unprecedented variety of morphologies and distribution of the two metals. We obtain spherical CuIn intermetallic and patchy phase-segregated Cu-In NCs, as well as dimer-like Cu-CuIn and Cu-In NCs. In particular, we find that segregation of the two metals occurs as the GRR progresses with time or with a higher copper precursor concentration. We discover size-dependent reaction kinetics, with the smaller In NCs undergoing a slower transition across the different Cu-In configurations. We compare the obtained results with the bulk Cu-In phase diagram and, interestingly, find that the bigger In NCs stabilize the bulk-like Cu-CuIn configuration before their complete segregation into Cu-In NCs. Finally, we also prove the utility of the new family of Cu-In NCs as model catalysts to elucidate the impact of the metal elemental distribution on the selectivity of these bimetallics toward the electrochemical CO reduction reaction. Generally, we demonstrate that the GRR is a powerful synthetic approach beyond noble metal-containing bimetallic structures, yet that the current knowledge on this reaction is challenged when oxophilic and poorly miscible metal pairs are used.
双金属纳米晶体 (NCs) 的组成和结构多样性提供了对其物理化学性质的卓越可调性，使它们在各种应用中具有吸引力，包括传感和催化。然而，操纵双金属 NCs 的特性决定因素仍然是一个挑战，特别是当远离贵金属时。在这项工作中，我们探索了 In NCs 和铜分子前体的电置换反应 (GRR)，以获得具有前所未有的多种形态和两种金属分布的 Cu-In 双金属 NCs。我们获得了球形 CuIn 金属间化合物和斑驳的相分离 Cu-In NCs，以及类似二聚体的 Cu-CuIn 和 Cu-In NCs。特别是，我们发现随着 GRR 的进行，随着时间的推移或铜前体浓度的增加，两种金属的分离会发生。我们发现了尺寸依赖的反应动力学，较小的 In NCs 经历较慢的转变，跨越不同的 Cu-In 构型。我们将获得的结果与大块 Cu-In 相图进行了比较，有趣的是，我们发现较大的 In NCs 在完全分离成 Cu-In NCs 之前稳定了类似于块状的 Cu-CuIn 构型。最后，我们还证明了新型 Cu-In NCs 作为模型催化剂的实用性，以阐明金属元素分布对这些双金属电化学 CO 还原反应选择性的影响。总的来说，我们证明了 GRR 是一种超越含贵金属的双金属结构的强大合成方法，但当使用亲氧和不易混溶的金属对时，当前对这种反应的认识受到了挑战。
