Beyond the catalytic activity of nanocatalysts, the support with architectural design and explicit boundary could also promote the overall performance through improving the diffusion process, highlighting additional support for the morphology-dependent activity. To delineate this, herein, a novel mazelike-reactor framework, namely multi-voids mesoporous silica sphere (MVmSiO 2 ), is carved through a top-down approach by endowing core-shell porosity premade Stöber SiO 2 spheres. The precisely-engineered MVmSiO 2 with peripheral one-dimensional pores in the shell and interconnecting compartmented voids in the core region is simulated to prove combined hierarchical and structural superiority over its analogous counterparts. Supported with CuZn-based alloys, mazelike MVmSiO 2 nanoreactor experimentally demonstrated its expected workability in model gas-phase CO 2 hydrogenation reaction where enhanced CO 2 activity, good methanol yield, and more importantly, a prolonged stable performance are realized. While tuning the nanoreactor composition besides morphology optimization could further increase the catalytic performance, it is accentuated that the morphological architecture of support further boosts the reaction performance apart from comprehensive compositional optimization. In addition to the found morphological restraints and size-confinement effects imposed by MVmSiO 2 , active sites of catalysts are also investigated by exploring the size difference of the confined CuZn alloy nanoparticles in CO 2 hydrogenation employing both in-situ experimental characterizations and density functional theory calculations.

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Solid siliceous (silica/silicate) materials remain a handy tool in assisting the defossilization efforts under the aegis of carbon capture and utilization (CCU) for extracting chemicals from “air” rather than “ground”....

Cerium(IV) oxide (CeO 2 ), or ceria, is one of the most abundant rare-earth materials that has been extensively investigated for its catalytic properties over the past two decades. However, due to the global scarcity and increasing cost of rare-earth materials, efficient utilization of this class of materials poses a challenging issue for the materials research community. Thus, this work is directed toward an exploration of making ultrathin hollow ceria or other rare-earth metal oxides and mixed rare-earth oxides in general. Such a hollow morphology appears to be attractive, especially when the thickness is trimmed to its limit, so that it can be viewed as a two-dimensional sheet of organized nanoscale crystallites, while remaining three-dimensional spatially. This ensures that both inner and outer shell surfaces can be better utilized in catalytic reactions if the polycrystalline sphere is further endowed with mesoporosity. Herein, we have devised our novel synthetic protocol for making ultrathin mesoporous hollow spheres of ceria or other desired rare-earth oxides with a tunable shell thickness in the region of 10 to 40 nm. Our ceria ultrathin hollow spheres are catalytically active and outperform other reported similar nanostructured ceria for the oxidation reaction of carbon monoxide in terms of fuller utilization of cerium. The versatility of this approach has also been extended to fabricating singular or multicomponent rare-earth metal oxides with the same ultrathin hollow morphology and structural uniformity. Therefore, this approach holds good promise for better utilization of rare-earth metal elements across their various technological applications, not ignoring nano-safety considerations.

Achieving the desired catalytic activity and selectivity in CO2 hydrogenation to methanol remains a grand challenge using nonprecious metals. Herein, the well-known ternary Cu-ZnO-ZrO2 (CZZ) was spatially sequestered as fine, uniformly dispersed active interfaces onto an engineered mesoporous silica sphere (MSS), giving rise to Cu-ZnO-ZrO2/MSS (CZZ-MSS) with confined binary Cu-ZnO/Cu-ZrO2 and ternary interfaces that fostered methanol production under moderate conditions (30 bar and 200–280 °C). By systematically investigating the CZZ-MSS performance, we show that spatial confinement and optimization of the interfacial environment of the catalytically active interfaces inside well-fabricated mesoporous silica deliver a markedly enhanced specific methanol yield (2211 gMEOH·kgCu –1·h–1) compared to conventional supported catalysts including an industrial catalyst (368 gMEOH·kgCu –1·h–1) and a vast majority of reported catalysts. Besides, the strong metal–support interaction arising from interacting metallic Cu and metal oxides (ZnO and ZrO2) within the confined, ultrasmall nanoparticles (<3.0 nm) demotes the sintering of Cu NPs while retaining their H2 dissociation strength, resulting in superior and prolonged catalytic stability over 100 h. In situ DRIFTS of confined catalysts with monophasic, biphasic, and triphasic interfaces expectedly suggests the occurrence of different CO2 hydrogenation reaction paths over triphasic Cu-ZnO-ZrO2/MSS (formate pathway) compared to monophasic Cu/MSS (reverse water–gas shift (RWGS) pathway) and biphasic ZnO-ZrO2/MSS. From the appreciable insights gained herein, the rational support synthesis bringing the confinement effect to the robust ZnO-Cu-ZrO2 interface is the rationale behind the higher rate of methanol synthesis observed in the CO2 hydrogenation.