Metal–organic frameworks (MOFs) have attracted enormous research interest as precursors/templates to prepare catalytic materials. However, the effect of structural isomerism of MOFs on the catalytic performance has rarely been studied. In this contribution, two topologically different Ce‐benzene tricarboxylate (Ce‐BTC) based on the same ligands and metal centers (viz., “MOF isomers”) are prepared and used as porous supports to load Pt nanoparticles (NPs), which shows distinct differences in porosities and loading behaviors of Pt. Strikingly, an irreversible framework transformation from tetragonal Ce‐BTC to monoclinic isomer is observed during water soaking treatment. The results give clear evidence that Pt/CeO2 derived from tetragonal Ce‐BTC inclines to produce more Pt0 and smaller Pt NPs, which eventually improve the catalytic performance for CO oxidation (T100 = 80 °C). In situ diffuse reflectance infrared Fourier transform spectroscopy analyses demonstrate that the adsorbed CO–Pt0 is the dominant intermediate for CO oxidation, rather than CO–Ptσ+ at the low temperature. Furthermore, MOF isomers based on the same structural units are also found in other Ln‐MOFs, such as Er‐BTC, Eu‐BTC, Y‐BTC, and Ce/Y‐BTC. Overall, this study affords a fundamental understanding of the effect of MOF structural isomers on the catalytic performance of the derived composites.

No abstract

Hybrid metal oxides with multilayered structures exhibit unique physical and chemical properties, particularly important to heterogeneous catalysis. However, regulations of morphology, spatial location, and shell numbers of the hybrid metal oxides still remain a challenge. Herein, binary Co 3 O 4 /ZnO nanocages with multilayered structures (up to eight layers) are prepared via chemical transformation from diverse Matryoshka-type zeolitic imidazolate frameworks (ZIFs) via a straightforward and scalable calcination method. More importantly, the obtained ZIF-derived metal oxides (ZDMOs) with versatile layer numbers exhibit remarkable catalytic activity for both gas-phase CO oxidation and CO 2 hydrogenation reactions, which are directly related to the sophisticated shell numbers (i.e., Co 3 O 4 -terminated layers or ZnO-terminated layers). Particularly, in situ reflectance infrared Fourier transform spectroscopy (DRIFTS) results indicate that the promotional effects of the multilayered structures indeed exist in CO 2 hydrogenation, wherein the key reaction intermediates are quite different for five-layer and six-layer ZDMOs. For instance, *HCOO is the predominant intermediate over the six-layer ZDMO; on the contrary, *H 3 CO is the crucial species over the five-layer ZDMO. The ZnO/Co 3 O 4 interface should be the active sites for CO 2 hydrogenation to *HCOO and *H 3 CO species, which are ultimately converted to the products (CH 4 or methanol). Accordingly, the work here provides a convenient way to facilely engineer multilayered Co 3 O 4 /ZnO nanocomposites with precisely controlled shell numbers for heterogeneous catalysis applications.

No abstract

No abstract