No abstract

Applying metal–organic frameworks (MOFs) on the surface of other materials to form multifunctional materials has recently attracted great attention; however, directing the MOF overgrowth is challenging due to the orders of magnitude differences in structural dimensions. In this work, we developed a universal strategy to mediate MOF growth on the surface of metal nanoparticles (NPs), by taking advantage of the dynamic nature of weakly adsorbed capping agents. During this colloidal process, the capping agents gradually dissociate from the metal surface, replaced in situ by the MOF. The MOF grows to generate a well-defined NP-MOF interface without a trapped capping agent, resulting in a uniform core–shell structure of one NP encapsulated in one single-crystalline MOF nanocrystal with specific facet alignment. The concept was demonstrated by coating ZIF-8 and UiO-66-type MOFs on shaped metal NPs capped by cetyltrimethylammonium surfactants, and the formation of the well-defined NP-MOF interface was monitored by spectroscopies. The defined interface outperforms ill-defined ones generated via conventional methods, displaying a high selectivity to unsaturated alcohols for the hydrogenation of an α,β-unsaturated aldehyde. This strategy opens a new route to create aligned interfaces between materials with vastly different structural dimensions.

No abstract

Encapsulating metal nanoparticles (NPs) in metal− organic frameworks (MOFs) to control catalytic selectivity has recently attracted great attention; however, an understanding of the NP−MOF interface is lacking. In this work, we used spectroscopy to investigate the interfacial structure and then demonstrate its impact on selectivity. Metal NPs were encapsulated in MOFs using three approaches, impregnation, coating, and one-pot methods. Chemical interactions at the interface were probed through IR and Raman spectroscopy. The fine differences between the interfacial structures generated by the three methods affected their selectivity for the hydrogenation of crotonaldehyde. The direct interface generated by the one-pot method provides the highest selectivity toward the desired crotyl alcohol. This work provides a spectroscopic protocol to study hybrid interfaces and sheds light on their design for effective NP−MOF catalysts.

Hydrothermal synthesis and characterization of titanosilicate ETS-10 was used as a means to prepare students for a research-focused independent term project as part of a 200-level descriptive inorganic chemistry course. Students spent the first 7 weeks of the course learning synthesis and characterization techniques that are common for metal oxide systems. In the second half of the semester, students led their own independent term projects as part of this research integrated laboratory course. All students successfully synthesized their materials and characterized their products independently. At the completion of the course, students submitted a journal-style report as well as presented their findings at a department poster session. The students were assessed through Student Assessment of their Learning Gains (SALG) surveys which showed enhancement in understanding and all-around research skills. The feasibility of learning advanced instrumentation that is not typically used in an undergraduate lab setting was demonstrated through this course.