Controlled Assembly of Hierarchical Metal Catalysts with Enhanced Performances

Abstract

Metal catalysts have been widely employed in chemical production, medicine manufacture, organic synthesis, and environmental cleaning, etc. Catalyst design plays a key role in enhancing efficiencies including activity, selectivity, and durability. Both theoretical predictions and experimental research has demonstrated that besides the composition, the morphology and/or the porous structure play key roles in determining catalytic performances. This review highlights the recent progress in the controlled synthesis of new metal catalysts with hierarchical structures mainly based on our research. First, we describe the metal catalysts with unique morphologies. Second, we show the metal catalysts with different porous structures. Finally, we summarize the metal catalysts with hierarchical structures. The catalytic performances of different catalysts are also included, and their correspondence to the catalyst structure is explored. This review might supply guidance for designing new and powerful metal catalysts for industrial applications.

Defect Dominated Hierarchical Ti‐Metal‐Organic Frameworks via a Linker Competitive Coordination Strategy for Toluene Removal

“…However, these methods usually result in limited pore size distribution, the introduction of impurities, or additional post‐treatment processes, like template removal, acid etching, high‐temperature annealing, and so on. [ 6,8–9,11 ] Therefore, the hierarchically porous MOFs with accurately customized pore size via a simple operation under relatively moderate conditions is highly desired. [ 12 ]…”

Encapsulating Mn3O4 Nanorods in a Shell of SiO2 Nanobubbles for Confined Fenton-Type Catalysis

“…24,25 Engineering the secondary architecture makes it possible to control the adsorption as well as the diffusion of reactants to the active sites and consequently the reaction performances. 26,27 Here, owing to the unique two-step process, a series of core−shell structured materials with adjustable secondary structures can be synthesized. First, the wellestablished Stober method 20 in the first step allows a facile The specific surface area of Mn 3 O 4 @SiO 2 NB-0.8 is 117 m 2 g −1 , which is significantly higher than that of pure Mn 3 O 4 (5 m 2 g −1 ) and Mn 3 O 4 @SiO 2 -0.8 (42 m 2 g −1 ).…”

“…It is acknowledged that the hierarchical structure of the nanomaterials has a significant influence on the catalytic, electronic, and sensing behaviors and optical properties. , Engineering the secondary architecture makes it possible to control the adsorption as well as the diffusion of reactants to the active sites and consequently the reaction performances. , Here, owing to the unique two-step process, a series of core–shell structured materials with adjustable secondary structures can be synthesized. First, the well-established Stöber method in the first step allows a facile regulation of the shell thickness by tuning the Si-to-Mn molar ratio.…”

Monodispersed Ruthenium Nanoparticles on Nitrogen-Doped Reduced Graphene Oxide for an Efficient Lithium–Oxygen Battery

“…A desirable solid catalyst for the Li–O 2 battery should fulfill the following criteria: (1) sufficient electrical conductivity; (2) superior stability against high operation voltage and nucleophilic attack by reactive oxygen species; (3) large surface area and/or porous structure for Li 2 O 2 accommodation; (4) pertinent binding energy toward discharge and charge reaction intermediates (e.g., O 2 •– , LiO 2 , and Li 2– x O 2 ); and (5) inertness to promote electrolyte degradation and efficacy to decompose side products (e.g., LiOH and Li 2 CO 3 ). According to Sabatier’s principle, noble metal catalysts are proposed to be the optimal choice as the heterogeneous catalysts for promoting the O 2 /Li 2 O 2 redox reaction, benefiting from the moderate binding energy between the noble metal and LiO 2 intermediates. − Among transitional metals, crystalline Pd locates near the apex of the “volcano plot”, indicating the proper interaction between LiO 2 and the metal surface for ORR in Li–O 2 batteries. ,, Whereas on carbon-based surfaces, such as glassy carbon and graphene, LiO 2 adsorption is very weak, which often results in the formation of randomly distributed Li 2 O 2 with a large crystal size and high polarization voltage. , The 3d metal of Co strongly bound to LiO 2 was recently shown to exhibit superior catalytic activity toward Li 2 O 2 formation and decomposition, attributable to the modulated electronic structure of Co sites on the N-doped carbon substrate. , This inspires us to further increase the efficacy of the metals for strengthening LiO 2 adsorption via interface engineering.…”