Rational confinement engineering of MOF-derived carbon-based electrocatalysts toward CO2 reduction and O2 reduction reactions
14 Oct 2021-
About: The article was published on 2021-10-14 and is currently open access. It has received 36 citations till now. The article focuses on the topics: Electrocatalyst & Carbon.
Citations
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TL;DR: In this paper , a simple strategy to regulate the components and coordination of Co-N-C catalysts at the atomic level by adjusting the Zn/Co ratio of bimetallic zeolitic imidazolate frameworks (ZnxCo1-ZIFs) was developed.
Abstract: Single oxygen-based advanced oxidation processes (1O2-AOPs) exhibit great prospects in selective degradation of organic pollutants. However, efficient production of 1O2 via tailored design of catalysts to achieve selective oxidation of contaminants remains challenging. Herein, we develop a simple strategy to regulate the components and coordination of Co-N-C catalysts at the atomic level by adjusting the Zn/Co ratio of bimetallic zeolitic imidazolate frameworks (ZnxCo1-ZIFs). Zn4Co1-C demonstrates 98% selective removal of phenol in the mixed phenol/benzoic acid (phenol/BA) solutions. Density functional theory calculations and experiments reveal that more active CoN4 sites are generated in Zn4Co1-C, which are beneficial to peroxymonosulfate activation to generate 1O2. Furthermore, the correlation between the origin of selectivity and well-defined catalysts is systematically investigated by the electron paramagnetic resonance test and quenching experiments. This work may provide novel insights into selective removal of target pollutants in a complicated water matrix.
70 citations
01 Jan 2015
TL;DR: The synergism of large surface area, multiscale porous structure, and good conductivity endows hierarchical carbon nanocages with high-level supercapacitive performances as mentioned in this paper.
Abstract: The synergism of large surface area, multiscale porous structure, and good conductivity endows hierarchical carbon nanocages with high-level supercapacitive performances. Further nitrogen doping greatly improves the hydrophilicity, which boosts the supercapacitive performances to an ultrahigh specific capacitance of up to 313 F g(-1) at 1 A g(-1).
68 citations
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TL;DR: In this article , the authors reveal the mechanism, thermodynamics and kinetics determining the HER/NRR efficiency on the state-of-the-art NRR electrocatalyst, Ru-N4, using grand canonical ensemble density functional theory (GCE-DFT).
Abstract: Electrochemical N2 reduction (NRR) to ammonia is seriously limited by the competing hydrogen evolution reaction (HER), but atomic-scale factors controlling HER/NRR competition are unknown. Herein we unveil the mechanism, thermodynamics, and kinetics determining the HER/NRR efficiency on the state-of-the-art NRR electrocatalyst, Ru-N4, using grand canonical ensemble density functional theory (GCE-DFT). We show that NRR/HER intermediates coadsorb on the catalyst where NRR intermediates suppress HER and selectivity is determined by the initial step forming *NNH or *H. Our results provide crucial insight into the complex NRR/HER competition, show the necessity of using GCE-DFT calculations, and suggest ways to improve NRR selectivity.
56 citations
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TL;DR: In this paper , the authors reveal the mechanism, thermodynamics and kinetics determining the HER/NRR efficiency on the state-of-the-art NRR electrocatalyst, Ru-N4, using grand canonical ensemble density functional theory (GCE-DFT).
Abstract: Electrochemical N2 reduction (NRR) to ammonia is seriously limited by the competing hydrogen evolution reaction (HER) but atomic-scale factors controlling HER/NRR competition are unknown. Herein we unveil the mechanism, thermodynamics, and kinetics determining the HER/NRR efficiency on the state-of-the-art NRR electrocatalyst, Ru-N4, using grand canonical ensemble density functional theory (GCE-DFT). We show that NRR/HER intermediates coadsorb on the catalyst where NRR intermediates suppress HER and selectivity is determined by the initial step forming *NNH or *H. Our results provide crucial insight into the complex NRR/HER competition, show the necessity of using GCE-DFT calculations, and suggest ways to improve NRR selectivity.
43 citations
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TL;DR: In this article , a general in situ topological transformation strategy for the integration of uniform Co-based species to fabricate a series of multishelled superstructures (MSSs) for CO2 photocatalytic conversion is demonstrated.
Abstract: Solar-driven conversion of CO2 is considered an efficient way to tackle the energy and environmental crisis. However, the photocatalytic performance is severely restricted due to the insufficient accessible active sites and inhibited electron transfer efficiency. This work demonstrates a general in situ topological transformation strategy for the integration of uniform Co-based species to fabricate a series of multishelled superstructures (MSSs) for CO2 photocatalytic conversion. Thorough characterizations reveal the obtained MSSs feature ultrathin Co-based nanosheet assembled polyhedral structures with tunable shell numbers, inner cavity sizes, and compositions. The superstructures increase the spatial density of Co-based active sites while maintaining their high accessibility. Further, the ultrathin nanosheets also facilitate the transfer of photogenerated electrons. As a result, the ZnCo bimetallic hydroxide featuring an ultrathin nanosheet assembled quadruple-shell hollow structure (ZnCo-OH QUNH) exhibits high photocatalytic efficiency toward CO2 reduction with a CO evolution rate of 134.2 μmol h-1 and an apparent quantum yield of 6.76% at 450 nm. The quasi in situ spectra and theoretical calculations disclose that Co sites in ZnCo-OH QUNH act as highly active centers to stabilize the COOH* intermediate, while Zn species play the role of adsorption sites for the [Ru(bpy)3]2+ molecules.
33 citations
References
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TL;DR: Metal-organic frameworks are porous materials that have potential for applications such as gas storage and separation, as well as catalysis, and methods are being developed for making nanocrystals and supercrystals of MOFs for their incorporation into devices.
Abstract: Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.
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TL;DR: An overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.
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TL;DR: Recent advances in preparation, characterization, and catalytic performance of SACs are highlighted, with a focus on single atoms anchored to metal oxides, metal surfaces, and graphene, offering the potential for applications in a variety of industrial chemical reactions.
Abstract: Supported metal nanostructures are the most widely used type of heterogeneous catalyst in industrial processes. The size of metal particles is a key factor in determining the performance of such catalysts. In particular, because low-coordinated metal atoms often function as the catalytically active sites, the specific activity per metal atom usually increases with decreasing size of the metal particles. However, the surface free energy of metals increases significantly with decreasing particle size, promoting aggregation of small clusters. Using an appropriate support material that strongly interacts with the metal species prevents this aggregation, creating stable, finely dispersed metal clusters with a high catalytic activity, an approach industry has used for a long time. Nevertheless, practical supported metal catalysts are inhomogeneous and usually consist of a mixture of sizes from nanoparticles to subnanometer clusters. Such heterogeneity not only reduces the metal atom efficiency but also frequent...
3,051 citations
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TL;DR: This Review will compare the results obtained from different systems and try to give a picture on how different types of metal species work in different reactions and give perspectives on the future directions toward better understanding of the catalytic behavior of different metal entities in a unifying manner.
Abstract: Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...
2,700 citations
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01 Jun 2018TL;DR: A review of single-atom catalysts can be found in this paper, where the authors discuss the utility of SACs in a broad scope of industrially important reactions and highlight the advantages these catalysts have over those presently used.
Abstract: Single-atom catalysis has arguably become the most active new frontier in heterogeneous catalysis. Aided by recent advances in practical synthetic methodologies, characterization techniques and computational modelling, we now have a large number of single-atom catalysts (SACs) that exhibit distinctive performances for a wide variety of chemical reactions. This Perspective summarizes recent experimental and computational efforts aimed at understanding the bonding in SACs and how this relates to catalytic performance. The examples described here illustrate the utility of SACs in a broad scope of industrially important reactions and highlight the advantages these catalysts have over those presently used. SACs have well-defined active centres, such that unique opportunities exist for the rational design of new catalysts with high activities, selectivities and stabilities. Indeed, given a certain practical application, we can often design a suitable SAC; thus, the field has developed very rapidly and afforded promising catalyst leads. Moreover, the control we have over certain SAC structures paves the way for designing base metal catalysts with the activities of noble metal catalysts. It appears that we are entering a new era of heterogeneous catalysis in which we have control over well-dispersed single-atom active sites whose properties we can readily tune. Single-atom catalysts are heterogeneous materials featuring active metals sites atomically dispersed on a surface. This Review describes methods by which we prepare and characterize these materials, as well as how we can tune their catalytic performance in a variety of important reactions.
2,306 citations