Controllable synthesis of ultrasmall atomically ordered intermetallic nanoparticles is a challenging task, owing to the high temperature commonly required for the formation of intermetallic phases. Here, a metal-organic framework (MOF)-confined co-reduction strategy is developed for the preparation of sub-2 nm intermetallic PdZn nanoparticles, by employing the well-defined porous structures of calcinated ZIF-8 (ZIF-8C) and an in situ co-reduction therein. HAADF-STEM, HRTEM, and EDS characterizations reveal the homogeneous dispersion of these sub-2 nm intermetallic PdZn nanoparticles within the ZIF-8C frameworks. XRD, XPS, and EXAFS measurements further confirm the atomically ordered intermetallic phase nature of these sub-2 nm PdZn nanoparticles. Selective hydrogenation of acetylene evaluation results show the excellent catalytic properties of the sub-2 nm intermetallic PdZn, which result from the energetically more favorable path for acetylene hydrogenation and ethylene desorption over the ultrasmall particles than over larger-sized intermetallic PdZn as revealed by density functional theory (DFT) calculations. Moreover, this protocol is also extendable for the preparation of sub-2 nm intermetallic PtZn nanoparticles and is expected to provide a novel methodology in synthesizing ultrasmall atomically ordered intermetallic nanomaterials by rationally functionalizing MOFs.

High‐performance, fully atomically dispersed single‐atom catalysts (SACs) are promising candidates for next‐generation industrial catalysts. However, it remains a great challenge to avoid the aggregation of isolated atoms into nanoparticles during the preparation and application of SACs. Here, the evolution of Pd species is investigated on different crystal facets of CeO2, and vastly different behaviors on the single‐atomic dispersion of surface Pd atoms are surprisingly discovered. In situ X‐ray photoelectron spectroscopy (XPS), in situ near‐ambient‐pressure‐XPS (NAP‐XPS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X‐ray absorption spectroscopy (XAS) reveal that, in a reducing atmosphere, more oxygen vacancies are generated on the (100) facet of CeO2, and Pd atoms can be trapped and thus feature atomic dispersion; by contrast, on the CeO2 (111) facet, Pd atoms will readily aggregate into clusters (Pdn). Furthermore, Pd1/CeO2(100) gives a high selectivity of 90.3% for the catalytic N‐alkylation reaction, which is 2.8 times higher than that for Pdn/CeO2(111). This direct evidence demonstrates the crucial role of crystal‐facet effects in the preparation of metal‐atom‐on‐metal‐oxide SACs. This work thus opens an avenue for the rational design and targeted synthesis of ultrastable and sinter‐resistant SACs.

The Well-defined multi-shelled intermetallic Ni3Ga hollow microspheres were firstly prepared with attractive properties.

No abstract

No abstract

Synthesis of crystalline mesoporous transition oxides is very challenging considering the crystallization of oxides is usually accompanied by the growth of crystalline grains that commonly results in pore collapse before crystallization. Here, we have developed a versatile template-free method and successfully realized general preparation of six mesoporous transition oxides such as CuO, CoO, and spinel MCo 2 O 4 (M = Co, Cu, Mn, and Zn). In addition, the mesoporous Co 3 O 4 is identified as surface-defect rich, which endows it with excellent catalaselike activity.

No abstract

No abstract