Designing Sites in Heterogeneous Catalysis: Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts?

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(9), P. 8594 - 8757

Published: March 3, 2022

A critical review of different prominent nanotechnologies adapted to catalysis is provided, with focus on how they contribute the improvement selectivity in heterogeneous catalysis. Ways modify catalytic sites range from use reversible or irreversible adsorption molecular modifiers immobilization tethering homogeneous catalysts and development well-defined solid surfaces. The latter covers methods for dispersion single-atom within supports as well complex nanostructures, it includes post-modification materials via processes such silylation atomic layer deposition. All these methodologies exhibit both advantages limitations, but all offer new avenues design specific applications. Because high cost most fact that resulting may limited thermal chemical stability, be best aimed at improving selective synthesis value-added chemicals, incorporated organic schemes, other applications are being explored address problems energy production, instance, greener processes. details each approaches discussed, representative examples provided. We conclude some general remarks future this field.

Language: Английский

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Single-Atom (Iron-Based) Catalysts: Synthesis and Applications

Chemical Reviews, Journal Year: 2021, Volume and Issue: 121(21), P. 13620 - 13697

Published: Oct. 13, 2021

Supported single-metal atom catalysts (SACs) are constituted of isolated active metal centers, which heterogenized on inert supports such as graphene, porous carbon, and oxides. Their thermal stability, electronic properties, catalytic activities can be controlled via interactions between the center neighboring heteroatoms nitrogen, oxygen, sulfur. Due to atomic dispersion amount required for catalysis decreased, thus offering new possibilities control selectivity a given transformation well improve catalyst turnover frequencies numbers. This review aims comprehensively summarize synthesis Fe-SACs with focus anchoring single atoms (SA) carbon/graphene supports. The characterization these advanced materials using various spectroscopic techniques their applications in diverse research areas described. When applicable, mechanistic investigations conducted understand specific behavior Fe-SACs-based highlighted, including use theoretical models.

Language: Английский

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Carbon nitride based materials: more than just a support for single-atom catalysis

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 52(15), P. 4878 - 4932

Published: Jan. 1, 2023

Recently, the missing link between homogeneous and heterogeneous catalysis has been found it was named single-atom (SAC). However, SAC field still faces important challenges, one of which is controlling bonding/coordination single atoms support in order to compensate for increase surface energy when particle size reduced due atomic dispersion. Excellent candidates meet this requirement are carbon nitride (CN)-based materials. Metal can be firmly trapped nitrogen-rich coordination sites CN materials, makes them a unique class hosts preparing catalysts (SACs). As most promising two-dimensional supports stabilize isolated metal atoms, materials have increasingly employed SACs. Herein, we will cover recent advances single-atoms supported by In review, characterization techniques challenges faced topic discussed, commonly synthetic methods delineated different Finally, catalytic performance SACs based on nitrides reviewed with special focus their photocatalytic applications. particular, prove as non-innocent support. The relationship two-way, where change electronic properties support, while features matrix tune activity reactions. highlight frontiers field, including analytical method development, truly controlled methods, allowing fine control loading multi-element synthesis, how understanding two-way exchange behind push next level.

Language: Английский

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Coordination modulation of iridium single-atom catalyst maximizing water oxidation activity

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: Jan. 10, 2022

Abstract Single-atom catalysts (SACs) have attracted tremendous research interests in various energy-related fields because of their high activity, selectivity and 100% atom utilization. However, it is still a challenge to enhance the intrinsic specific activity SACs. Herein, we present an approach fabricate surface distribution density iridium (Ir) SAC on nickel-iron sulfide nanosheet arrays substrate (Ir 1 /NFS), which delivers water oxidation activity. The Ir /NFS catalyst offers low overpotential ~170 mV at current 10 mA cm −2 turnover frequency 9.85 s −1 300 1.0 M KOH solution. At same time, exhibits stability performance, reaching lifespan up 350 hours 100 . First-principles calculations reveal that electronic structures atoms are significantly regulated by substrate, endowing energetically favorable reaction pathway. This work represents promising strategy single-atom with durability for electrochemical splitting.

Language: Английский

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Recent Developments of Microenvironment Engineering of Single‐Atom Catalysts for Oxygen Reduction toward Desired Activity and Selectivity

Advanced Functional Materials, Journal Year: 2021, Volume and Issue: 31(45)

Published: Aug. 7, 2021

Abstract Oxygen reduction reaction (ORR) is an essential process for sustainable energy supply and sufficient chemical production in modern society. Single‐atom catalysts (SACs) exhibit great potential on maximum atomic efficiency, high ORR activity, stability, making them attractive candidates pursuing next‐generation catalysts. Despite substantial efforts being made building diversiform single‐atom active sites (SAASs), the performance of obtained still unsatisfactory. Fortunately, microenvironment regulation SACs provides opportunities to improve activity selectivity ORR. In this review, first, mechanism pathways N‐coordinated SAAS, electrochemical evaluation, characterization SAAS are displayed. addition, recent developments tuning systematically summarized, especially, strategies modulation introduced detail boosting intrinsic 4e − /2e selectivity. Theoretical calculations cutting‐edge techniques united discussed fundamental understanding synthesis–construction–performance correlations. Furthermore, their comprehensively overviewed acquire outstanding SACs. Lastly, by proposing perspectives remaining challenges infant engineering, future directions other analogous procedures pointed out.

Language: Английский

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Silver nanomaterials: synthesis and (electro/photo) catalytic applications

Chemical Society Reviews, Journal Year: 2021, Volume and Issue: 50(20), P. 11293 - 11380

Published: Jan. 1, 2021

In view of their unique characteristics and properties, silver nanomaterials (Ag NMs) have been used not only in the field nanomedicine but also for diverse advanced catalytic technologies. this comprehensive review, light is shed on general synthetic approaches encompassing chemical reduction, sonochemical, microwave, thermal treatment among preparative methods syntheses Ag-based NMs applications. Additionally, some latest innovative such as continuous flow integrated with MW other benign emphasized that ultimately pave way sustainability. Moreover, potential applications emerging Ag NMs, including sub single atoms, liquid-phase catalysis, photocatalysis, electrocatalysis well a positive role reactions are meticulously summarized. The scientific interest synthesis lies benefits activity, selectivity, stability, recovery. Therefore, rise journey NM-based catalysts will inspire new generation chemists to tailor design robust can effectively tackle major environmental challenges help replace noble metals This overview concludes by providing future perspectives research into arena photocatalysis.

Language: Английский

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Advanced Strategies for Stabilizing Single-Atom Catalysts for Energy Storage and Conversion

Electrochemical Energy Reviews, Journal Year: 2022, Volume and Issue: 5(3)

Published: Sept. 1, 2022

Well-defined atomically dispersed metal catalysts (or single-atom catalysts) have been widely studied to fundamentally understand their catalytic mechanisms, improve the efficiency, increase abundance of active components, enhance catalyst utilization, and develop cost-effective effectively reduce usage noble metals. Such relatively higher selectivity activity with maximum atom utilization due unique characteristics high dispersion a low-coordination environment. However, freestanding single atoms are thermodynamically unstable, such that during synthesis reactions, they inevitably tend agglomerate system energy associated large surface areas. Therefore, developing innovative strategies stabilize catalysts, including mass-separated soft landing, one-pot pyrolysis, co-precipitation, impregnation, atomic layer deposition, organometallic complexation, is critically needed. Many types supporting materials, polymers, commonly used in these fabrication techniques. Herein, we review stabilization catalyst, different methods, specific metals carriers, advantages disadvantages. In particular, this focuses on application polymers functions as carriers for atoms, synthetic templates, encapsulation agents, protection agents process. The technical challenges currently faced by summarized, perspectives related future research directions enhancement loading content, large-scale implementation proposed realize practical applications. Single-atom characterized dispersibility, weak coordination environments, selectivity, highest utilization. free area, individual usually unstable prone agglomeration reactions. researchers developed strategies, sedimentation, coprecipitation, step reduction, precipitation, This article summarizes from aspects support types, reaction its focus preparation role manufacturing main feature polymer-derived materials contain abundant heteroatoms, N, possess lone-pair electrons. These electrons can anchor through strong interactions. environment facilitate formation because enlarge average distance precursor adsorbed polymer matrix. Polymers nitrogen groups favorable candidates dispersing weakening tendency aggregation redistributing charge densities around performance. provides summary analysis current directions, mechanism sufficiently loading, implementation.

Language: Английский

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Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

ACS Nano, Journal Year: 2022, Volume and Issue: 16(6), P. 8557 - 8618

Published: May 31, 2022

Direct conversion of methane (CH4) to C1–2 liquid oxygenates is a captivating approach lock carbons in transportable value-added chemicals, while reducing global warming. Existing approaches utilizing the transformation CH4 fuel via tandemized steam reforming and Fischer–Tropsch synthesis are energy capital intensive. Chemocatalytic partial oxidation remains challenging due negligible electron affinity, poor C–H bond polarizability, high activation barrier. Transition-metal stoichiometric catalysts harsh oxidants reaction conditions perform poorly with randomized product distribution. Paradoxically, which active enough break also promote overoxidation, resulting CO2 generation reduced carbon balance. Developing can bonds selectively make useful chemicals at mild vital commercialization. Single atom (SACs) specifically coordinated metal centers on support have displayed intrigued reactivity selectivity for oxidation. SACs significantly reduce induced electrostatic polarization facilitate accelerated rate low temperature. The distinct metal–support interaction stabilize intermediate prevent overoxidation products. present review accounts recent progress field selective oxygenates. chemical nature catalytic sites, effects interaction, stabilization species minimize thoroughly discussed forward-looking perspective improve performance.

Language: Английский

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Atomic manganese coordinated to nitrogen and sulfur for oxygen evolution

Nano Research, Journal Year: 2022, Volume and Issue: 15(7), P. 6019 - 6025

Published: April 25, 2022

Language: Английский

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Single-atom catalysts for photocatalytic hydrogen evolution: A review

International Journal of Hydrogen Energy, Journal Year: 2022, Volume and Issue: 47(40), P. 17583 - 17599

Published: April 15, 2022

Language: Английский

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