Preferred Interfacial Alignment in the Pd@HKUST1 System and the Role of the MOF to Affect Charge Transfer to Pd Nanoparticles

RF Heden and P Clancy, JOURNAL OF PHYSICAL CHEMISTRY C, 126, 11709-11714 (2022).

DOI: 10.1021/acs.jpcc.2c00021

A well-studied material, designated as Pd@HKUST-1, has attracted considerable interest due to its exceptionally high uptake of hydrogen. Pd@HKUST-1 consists of large (10 nm diameter) palladium nanocrystals dispersed within a metal organic framework (MOF). This computational study uses molecular dynamics simulations to uncover the currently unknown structure of the interface between the Pd nanocubes and the surrounding HKUST-1 MOF, revealing significant preferences regarding which crystal planes of the MOF prefer to interact with the Pd. A complementary approach, density functional theory (DFT), is used to investigate how the interfacial structure of Pd@HKUST-1 leads to its superior hydrogen absorption ability. We observe that although the MOF withdraws electron density from the palladium, it also induces regions of negative charge that likely contribute to the system's high hydrogen absorption.

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