Tailoring the Coordination Micro-Environment in Nanotraps for Efficient Platinum/Palladium Separation.

Recovering platinum group metals from secondary resources is crucial to meet the growing demand for high-tech applications. Various techniques have been explored, and adsorption using porous materials has emerged as a promising technology due to its efficient performance and environmental beingness. However, the challenge lies in effectively recovering and separating individual PGMs given their similar chemical properties. Herein, we present a breakthrough approach by sophisticatedly tailoring the coordination micro-environment in a series of aminopyridine-based porous organic polymers, which enables the creation of platinum-specific nanotraps for efficient separation of binary PGMs (platinum/palladium). The newly synthesized POP-o2NH2-Py demonstrated record uptakes and selectivity towards platinum over palladium, with the amino groups adjacent to the pyridine moieties being vital in improving platinum binding performance. Further breakthrough experiments underlined its remarkable ability to separate platinum and palladium. Spectroscopic analysis reveals that POP-o2NH2-Py offers a more favorable coordination fashion to platinum ions compared to palladium ions owing to the greater interaction between N and Pt4+ and stronger intramolecular hydrogen bonding between the amino groups and four coordinating chlorines at platinum. These findings underscore the importance of fine-tuning the coordination micro-environment of nanotraps through subtle modifications that can greatly enhance the selectivity towards the desired metal ions. This article is protected by copyright. All rights reserved.