Designing highly efficient and durable electrocatalysts that accelerate sluggish oxygen reduction reaction kinetics for fuel cells and metal–air batteries are highly desirable but challenging. Herein, a facile yet robust strategy is reported to rationally design single iron active centers synergized with local S atoms in metal–organic frameworks derived from hierarchically porous carbon nanorods (Fe/N,S‐HC). The cooperative trithiocyanuric acid‐based coating not only introduces S atoms that regulate the coordination environment of the active centers, but also facilitates the formation of a hierarchically porous structure. Benefiting from electronic modulation and architectural functionality, Fe/N,S‐HC catalyst shows markedly enhanced ORR performance with a half‐wave potential (E1/2) of 0.912 V and satisfactory long‐term durability in alkaline medium, outperforming those of commercial Pt/C. Impressively, Fe/N,S‐HC‐based Zn–air battery also presents outstanding battery performance and long‐term stability. Both electrochemical experimental and density functional theoretical (DFT) calculated results suggest that the FeN4 sites tailored with local S atoms are favorable for the adsorption/desorption of oxygen intermediate, resulting in lower activation energy barrier and ultraefficient oxygen reduction catalytic activity. This work provides an atomic‐level combined with porous morphological‐level insights into oxygen reduction catalytic property, promoting rational design and development of novel highly efficient single‐atom catalysts for the renewable energy applications.
Mercury intrusion capillary pressure (MICP), nuclear magnetic resonance (NMR), routine core analysis, thin sections, and scanning electron microscope (SEM) analysis were used to gain insight into the pore structure of the Eocene Sha-3 (the third member of the Shahejie formation) low-permeability sandstones in the Raoyang sag, including pore type, pore geometry, and pore size. Quantitative NMR parameters and petrophysical properties were integrated to build up the relationship between microscopic pore structure and macroscopic performance. The pore systems of Sha-3 sandstones are dominantly of residual intergranular pores, intragranular dissolution pores, and intercrystallite micropores associated with authigenic clay minerals. The high threshold pressure and low mercury withdrawal efficiencies from MICP analysis indicate the poor pore connectivity and strong heterogeneous. Both uni-and bimodal transverse relaxation time (T 2 ) spectrum can be found because of the coexistence of small and large pores, and the T 2 of major pore size occurring at about 1.0 to 100 ms. The Sha-3 sandstones have a relatively high irreducible water content and short T 2 components in the T 2 range. Long T 2 components can only be observed in samples rich in large pores or microfractures. T 2gm (the geometric mean of the T 2 distribution) correlates well with irreducible water saturation and permeability. A methodology for pore structure classification is presented integrating NMR parameters of T 2gm , bulk volume of immovable fluid (BVI), and petrophysical parameters such as reservoir quality index (RQI) and permeability. Consequently, four types of pore structures (types A, B, C, and D) are identified, and characteristics of individual pore structure are summarized. The comprehensive analysis of NMR measurements combined with thin sections, SEM and MICP analysis is useful for describing microscopic pore structure, which is important to maintaining and enhancing petroleum recovery in low-permeability sandstone reservoirs.
(3D) hierarchical materials with
spatial compartmentalization of multiple catalytic functionalities
effectively facilitates the chemical processes’ intensification,
especially for bulky-molecule-involved cascade reaction. Herein, a
facile and novel core–shell colloidal crystal templating strategy
was developed to synthesize highly ordered arrays of integrated yolk–shelled
nanoreactor consisting of monolithically interconnected ZIF-8 shell
and sulfonated polystyrene yolks decorated with rhodium nanoparticles.
The obtained nanoreactor achieves efficient catalytic one-pot cascade
Knoevenagel condensation-hydrogenation reactions for larger molecules,
by taking advantage of the superior mass diffusion properties of the
hierarchical macro/microporous metal–organic framework (MOF)
skeleton, robust monolith nature, and spatially separated functionalities.
This work offers an important strategy for preparing MOF-based composites
with a hierarchical framework, accelerating various applications of
MOFs, such as electrochemical applications, photothermal conversion,
and heterogeneous catalysis.
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