Mason Jarrett L, Huizenga Caleb D, Ray Manisha, Kafader Jared O, Jarrold Caroline Chick
Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405, United States.
J Phys Chem A. 2023 Aug 17;127(32):6749-6763. doi: 10.1021/acs.jpca.3c03738. Epub 2023 Aug 2.
Beyond the now well-known strong catalyst-support interactions reported for ceria-supported platinum catalysts, intermetallic Ce-Pt compounds exhibit fascinating properties such as heavy fermion behavior and magnetic instability. Small heterometallic Ce-Pt clusters, which can provide insights into the local features that govern bulk phenomena, have been less explored. Herein, the anion photoelectron spectra of three small mixed Ce-Pt clusters, CeOPt, CePt, and CePt, are presented and interpreted with supporting density functional theory calculations. The calculations, which are readily reconciled with the experimental spectra, suggest the presence of numerous close-lying spin states, including states in which the Ce 4 electrons are ferromagnetically coupled or antiferromagnetically coupled. The Pt center is consistently in a nominal -2 charge state in all cluster neutrals and anions, giving the Ce-Pt bond ionic character. Ce-Pt bonds are stronger than Ce-Ce bonds, and the O atom in CeOPt coordinates only with the Ce centers. The energy of the singly occupied Ce-local 4 orbitals relative to the Pt-local orbitals changes with cluster composition. Discussion of the results includes potential implications for Ce-rich intermetallic materials.
除了目前已知的氧化铈负载的铂催化剂所具有的强烈的催化剂-载体相互作用外，金属间化合物Ce-Pt还表现出迷人的特性，如重费米子行为和磁不稳定性。小型异金属Ce-Pt团簇能够为支配整体现象的局部特征提供见解，但目前对其研究较少。在此，我们给出了三种小型混合Ce-Pt团簇CeOPt、CePt和CePt的阴离子光电子能谱，并通过支持性的密度泛函理论计算对其进行了解释。这些计算结果与实验光谱很容易吻合，表明存在大量紧密相邻的自旋态，包括Ce 4电子呈铁磁耦合或反铁磁耦合的状态。在所有团簇中性体和阴离子中，Pt中心始终处于名义上的-2电荷状态，赋予Ce-Pt键离子特性。Ce-Pt键比Ce-Ce键更强，并且CeOPt中的O原子仅与Ce中心配位。相对于Pt局部轨道，单占据的Ce局部4轨道的能量随团簇组成而变化。结果讨论包括对富Ce金属间材料的潜在影响。
