d–sp orbital hybridization: a strategy for activity improvement of transition metal catalysts

Chen, Hui; Wu, Qiannan; Wang, Yanfei; Zhao, Qinfeng; Shen, Ya‐Ching; Zou, Xiaoxin

doi:10.1039/d2cc02299k

Cited by 68 publications

(34 citation statements)

References 116 publications

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“…At the same time, the PDOS of the catalyst active sites and the adsorbate elements connected to active sites in adsorption configurations (Figure ) were investigated. For NH 3 adsorption (Figure ), d-sp hybridization occurred between N and Mn elements (Figure a, c, e, and g), which can establish a channel for electron transport between NH 3 and the active sites, enhance the transfer of charges, and promote further diffusion and reaction of NH 3 . Furthermore, Mn on T1 contributed more electrons than Mn on T3 and was closer to the Fermi level, which leads to strong bonding and the delocalization of electrons.…”

Section: Resultsmentioning

confidence: 99%

Rational Regulation of Reducibility and Acid Site on Mn–Fe–BTC to Achieve High Low-Temperature Catalytic Denitration Performance

Song

Guo

et al. 2023

ACS Appl. Mater. Interfaces

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Selective catalytic reduction with ammonia is the mainstream technology of flue gas denitration (de-NO x ). The reducibility and acid site are two important factors affecting the de-NO x performance, and effective regulation between them is the key to obtain a highly efficient de-NO x catalyst. Herein, a series of Mn−Fe−BTC with different ratios of Mn and Fe are synthesized, among which 2Mn-1Fe-BTC with 2:1 molar ratio of Mn and Fe has excellent low-temperature (LT) de-NO x performance (above 90% NO conversion between 60 and 270 °C) and good tolerance to H 2 O and SO 2 poisoning (88% NO conversion at 150 °C with 100 ppm of SO 2 and/or 6% H 2 O). It is revealed that the reducibility properties and acid sites of Mn−Fe− BTC can be flexibly tuned by the ratio of Mn and Fe. The difference in electronegativity between Fe and Mn leads to the redistribution of valence electrons, which enables the controllable reducibility of Mn−Fe−BTC. Furthermore, different amounts of Mn and Fe lead to different electron transport, which determines the type and number of acid sites. The synergistic effect of Mn and Fe endows Mn−Fe−BTC with enhanced surface molecular adsorption capacity and enables the catalyst to selectively chemisorb NH 3 and NO at different active sites. This research provides guidance for the flexible regulation of reducibility and acid site of LT de-NO x catalyst.

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Section: Resultsmentioning

confidence: 99%

Rational Regulation of Reducibility and Acid Site on Mn–Fe–BTC to Achieve High Low-Temperature Catalytic Denitration Performance

Song

Guo

et al. 2023

ACS Appl. Mater. Interfaces

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“…The corresponding dissociation energy was −5.591 eV on Rh 38 , significantly lower than that on Rh 13 (−4.032 eV) and Rh 55 (−3.637 eV). The higher d orbital center of Rh 38 leads to less occupation of antibonding states for the adsorbate and thus stronger binding strength 55 (Table S2). This is in line with the experimental observations that the subnanometer Rh NC with an average diameter of 0.9 nm possessed the highest ability in H 2 O 2 activation to generate • OH radicals, which accounts for the highest site-specific reactivity in methane conversion.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Controlled-Release Mechanism Regulates Rhodium Migration and Size Redistribution Boosting Catalytic Methane Conversion

Shen

Xiao

et al. 2023

ACS Catal.

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The migration of Rh atoms under a gas/reactive environment has a great impact on the dynamic restructuring and size redistribution of Rh catalysts in a variety of structure-sensitive catalytic reactions. To date, regulating the size distribution of active Rh species via controlled atomic migration remains challenging. Here, we show a controlled-release mechanism to regulate Rh atom migration through two-dimensional (2D) zeolite nanosheets, enabling quasi-continuous size redistribution of active Rh species from a single atom to nanoparticles with reversibility. Utilizing state-of-the-art in situ characterizations, a reversible aggregation/redispersion of Rh catalysts in/out of the 2D zeolite was directly observed under H2 or CO environment. The interplay between gas environment and support confinement was disclosed that substantially restrained the dynamic migration of Rh species and enabled a quasi-continuous control of Rh size distribution over a wide temperature window and size range. The catalytic testing for mild oxidation of methane demonstrated a volcano correlation of methanol activity with increasing particle size. The sub-nanometer Rh clusters with an average diameter of 0.9 nm exhibited the highest methanol activity of 39.7 molCH3OOH·molRh –1·h–1 with remarkable selectivity as high as 73.2%, far beyond that of single atom species and larger particles. Density functional theory calculations and electron paramagnetic resonance spectroscopy further revealed that this size dependency is related to the preferential formation of •OH radicals on Rh clusters with different sizes, which acts as a key initiator for methane activation. Our results thus provide a practical approach to synthesize size-specific metal catalysts via controlled atomic migration.

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“…The synergetic interaction among them can potentially enhance the intrinsic activity of metal sites and stability of electrocatalysts, such as in the case of the Ni 2 Fe(CN) 6 electrocatalyst where an enhanced urea oxidation and limited transformation of catalysts were explained by the synergetic effect of Ni and Fe sites . Therefore, a collective effect of metal–metal sites, namely correlated SACs (C-SACs), has attracted increasing attention. , This synergetic interaction can readily adjust their electronic structures by changing the level of orbital hybridization and antiorbital filling, which are highly related to the intrinsic electrocatalytic activity. , For example, Ir C-SACs were synthesized with the integration of Ir atoms into the framework of the cobalt oxide host offering great corrosion resistance and OER activity . Including the metal–support interaction, an Ir–Ir short-range order can be identified by HAADF-STEM and pair distribution function analysis.…”

Section: Tailoring Strategies On Active Sites Via a Synergistic Effec...mentioning

confidence: 99%

“… 140 , 141 This synergetic interaction can readily adjust their electronic structures by changing the level of orbital hybridization and antiorbital filling, which are highly related to the intrinsic electrocatalytic activity. 142 , 143 For example, Ir C-SACs were synthesized with the integration of Ir atoms into the framework of the cobalt oxide host offering great corrosion resistance and OER activity. 141 Including the metal–support interaction, an Ir–Ir short-range order can be identified by HAADF-STEM and pair distribution function analysis.…”

Section: Tailoring Strategies On Active Sites Via a Synergistic Effec...mentioning

confidence: 99%

Tailoring of Active Sites from Single to Dual Atom Sites for Highly Efficient Electrocatalysis

et al. 2022

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Single atom catalysts (SACs) have been attracting extensive attention in electrocatalysis because of their unusual structure and extreme atom utilization, but the low metal loading and unified single site induced scaling relations may limit their activity and practical application. Tailoring of active sites at the atomic level is a sensible approach to break the existing limits in SACs. In this review, SACs were first discussed regarding carbon or non-carbon supports. Then, five tailoring strategies were elaborated toward improving the electrocatalytic activity of SACs, namely strain engineering, spin-state tuning engineering, axial functionalization engineering, ligand engineering, and porosity engineering, so as to optimize the electronic state of active sites, tune d orbitals of transition metals, adjust adsorption strength of intermediates, enhance electron transfer, and elevate mass transport efficiency. Afterward, from the angle of inducing electron redistribution and optimizing the adsorption nature of active centers, the synergistic effect from adjacent atoms and recent advances in tailoring strategies on active sites with binuclear configuration which include simple, homonuclear, and heteronuclear dual atom catalysts (DACs) were summarized. Finally, a summary and some perspectives for achieving efficient and sustainable electrocatalysis were presented based on tailoring strategies, design of active sites, and in situ characterization.

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d–sp orbital hybridization: a strategy for activity improvement of transition metal catalysts

Abstract: Orbital hybridization to regulate the electronic structures and surface chemisorption properties of transition metals has been extensively investigated for researching high-performance catalysts toward various reactions. Unlike conventional d−d hybridization, the...

Cited by 68 publications

References 116 publications

Rational Regulation of Reducibility and Acid Site on Mn–Fe–BTC to Achieve High Low-Temperature Catalytic Denitration Performance

Rational Regulation of Reducibility and Acid Site on Mn–Fe–BTC to Achieve High Low-Temperature Catalytic Denitration Performance

Controlled-Release Mechanism Regulates Rhodium Migration and Size Redistribution Boosting Catalytic Methane Conversion

Tailoring of Active Sites from Single to Dual Atom Sites for Highly Efficient Electrocatalysis

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