scholarly journals Single-atom nanozymes

2019 ◽  
Vol 5 (5) ◽  
pp. eaav5490 ◽  
Author(s):  
Liang Huang ◽  
Jinxing Chen ◽  
Linfeng Gan ◽  
Jin Wang ◽  
Shaojun Dong
Keyword(s):  
Active Sites ◽  
Synergistic Effects ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Size Composition ◽  
Underlying Mechanism ◽  
Catalytic Performance ◽  
Axial Ligand ◽  
Single Atom ◽  
Active Centers

Conventional nanozyme technologies face formidable challenges of intricate size-, composition-, and facet-dependent catalysis and inherently low active site density. We discovered a new class of single-atom nanozymes with atomically dispersed enzyme-like active sites in nanomaterials, which significantly enhanced catalytic performance, and uncovered the underlying mechanism. With oxidase catalysis as a model reaction, experimental studies and theoretical calculations revealed that single-atom nanozymes with carbon nanoframe–confined FeN5 active centers (FeN5 SA/CNF) catalytically behaved like the axial ligand–coordinated heme of cytochrome P450. The definite active moieties and crucial synergistic effects endow FeN5 SA/CNF with a clear electron push-effect mechanism, as well as the highest oxidase-like activity among other nanozymes (the rate constant is 70 times higher than that of commercial Pt/C) and versatile antibacterial applications. These suggest that the single-atom nanozymes have great potential to become the next-generation nanozymes.

scholarly journals Platinum–copper single atom alloy catalysts with high performance towards glycerol hydrogenolysis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xi Zhang ◽  
Guoqing Cui ◽  
Haisong Feng ◽  
Lifang Chen ◽  
Hui Wang ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Value Added ◽  
Catalytic Performance ◽  
Single Atom ◽  
Glycerol Hydrogenolysis ◽  
Single Atom Alloy

AbstractSelective hydrogenolysis of biomass-derived glycerol to propanediol is an important reaction to produce high value-added chemicals but remains a big challenge. Herein we report a PtCu single atom alloy (SAA) catalyst with single Pt atom dispersed on Cu nanoclusters, which exhibits dramatically boosted catalytic performance (yield: 98.8%) towards glycerol hydrogenolysis to 1,2-propanediol. Remarkably, the turnover frequency reaches up to 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1, which is to our knowledge the largest value among reported heterogeneous metal catalysts. Both in situ experimental studies and theoretical calculations verify interface sites of PtCu–SAA serve as intrinsic active sites, in which the single Pt atom facilitates the breakage of central C–H bond whilst the terminal C–O bond undergoes dissociation adsorption on adjacent Cu atom. This interfacial synergistic catalysis based on PtCu–SAA changes the reaction pathway with a decreased activation energy, which can be extended to other noble metal alloy systems.

scholarly journals Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanming Cai ◽  
Jiaju Fu ◽  
Yang Zhou ◽  
Yu-Chung Chang ◽  
Qianhao Min ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Active Sites ◽  
Theoretical Calculations ◽  
High Energy ◽  
Single Atom ◽  
Faradaic Efficiency ◽  
High Energy Barrier ◽  
Catalytic Sites ◽  
Electron Reduction ◽  
First Time

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

scholarly journals Dynamic Structural Changes in Nickel Single-Atom Catalysts During Electrochemical Reduction of CO2 to CO

2021 ◽  
Author(s):  
Bingbao Mei ◽  
Changzhi Ai ◽  
Lushan Ma ◽  
Cong Liu ◽  
Shuai Yang ◽  
...  
Keyword(s):  
Active Sites ◽  
Structural Changes ◽  
Theoretical Calculations ◽  
Reduction Reaction ◽  
Single Atom ◽  
Structure Evolution ◽  
Potential Range ◽  
Dynamic Configuration ◽  
Carbon Abatement ◽  
Reduction Of Co2

Abstract Electrochemical CO2 reduction reaction (ECO2RR) is an important route for global carbon abatement. However, a comprehensive picture of the structure evolution of metal active sites is currently lacked in ECO2RR. Here, we present the first full view of Ni single-atom catalyst for ECO2RR over a broad potential range. Comprehensive X-ray absorption spectroscopy (XAS) analyses confirmed the Ni coordinated with pyrrole nitrogen in the form of Ni-N4 attached with an axial O2 ligand. Operando XAS revealed the precise structure of the Ni single-atom catalyst that dynamically changes with the shift of applied potentials. Such changes ultimately contributed to the CO selectivity variation ranging from 20%-99%. Interestingly, the Ni center was found to move toward the N4 plane during the ECO2RR, which played a crucial role of reaching near-unity CO selectivity. Together with theoretical calculations, a clear quantitative correlation between the dynamic configuration and the catalytic properties was established.

scholarly journals A Mini Review of the Preparation and Photocatalytic Properties of Two-Dimensional Materials

2020 ◽  
Vol 8 ◽  
Author(s):  
Shuhua Hao ◽  
Xinpei Zhao ◽  
Qiyang Cheng ◽  
Yupeng Xing ◽  
Wenxuan Ma ◽  
...  
Keyword(s):  
Active Sites ◽  
2D Materials ◽  
Chemical Properties ◽  
Metal Sulfide ◽  
Catalytic Performance ◽  
Theoretical Research ◽  
Single Atom ◽  
Preparation Methods ◽  
Two Dimensional Materials ◽  
Physical And Chemical

The successful preparation and application of graphene shows that it is feasible for the materials with a thickness of a single atom or few atomic layers to exist stably in nature. These materials can exhibit unusual physical and chemical properties due to their special dimension effects. At present, researchers have made great achievements in the preparation, characterization, modification, and theoretical research of 2D materials. Because the structure of 2D materials is often similar, it has a certain degree of qualitative versatility. Besides, 2D materials often carry good catalytic performance on account of their more active sites and adjustable harmonic electronic structure. In this review, taking 2D materials as examples [graphene, boron nitride (h-BN), transition metal sulfide and so on], we review the crystal structure and preparation methods of these materials in recent years, focus on their photocatalyst properties (carbon dioxide reduction and hydrogen production), and discuss their applications and development prospects in the future.

Effects of Lanthanum on the Structure and the Catalytic Performance of Ni/Al2O3 Catalysts for the Hydrotreating of Crude 2-Ethylhexanol

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Renchun Yang ◽  
Xiaogang Li ◽  
Junsheng Wu ◽  
Xin Zhang ◽  
Zhihua Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Performance ◽  
Deposition Method ◽  
Active Centers ◽  
Hydrothermal Deposition ◽  
H2 Chemisorption ◽  
Ni Content ◽  
Dispersion Degree ◽  
Catalytic Active Sites

To study the effects of La modifier on Ni/γ-Al2O3 catalysts for the hydrotreating of crude 2-ethylhexanol, four samples with various La contents were prepared by the hydrothermal deposition method and characterized by ICP–AES, XRD, XPS, TPR, and H2 chemisorption. It was found that the number of catalytic active sites of the four samples with a similar Ni loading follows the order: Ni/La0/Al (13.2μmol gcat-1) < Ni/La0.5/Al (15.1μmol gcat-1) < Ni/La2.0/Al (15.8μmol gcat-1) < Ni/La1.0/Al (17.1μmol gcat-1). The results indicate that the catalyst modified by an appropriate La can obtain more active centers and higher hydrogenation performance because it possesses a higher surface Ni content and an appropriate Ni dispersion degree.

scholarly journals Highly-efficient RuNi single-atom alloy catalysts toward chemoselective hydrogenation of nitroarenes

2021 ◽  
Author(s):  
Wei Liu ◽  
Yusen Yang ◽  
Haisong Feng ◽  
Yiming Niu ◽  
Lei Wang ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
High Performance ◽  
Heterogeneous Catalysts ◽  
Theoretical Calculations ◽  
Single Atom ◽  
Structure Property ◽  
Active Centers ◽  
Preferential Cleavage ◽  
Rate Determining Step ◽  
Single Atom Alloy

Abstract The design and exploitation of high-performance catalysts as well as understanding the structure-property correlation have gained considerable attention in selective hydrogenation reactions, but remain a huge challenge. Herein, we report a RuNi single atom alloy (SAA) in which Ru single atoms are anchored onto Ni nanoparticle surface via Ru–Ni coordination accompanied with electron transfer from sub-surface Ni to Ru. The optimal catalyst 0.4% RuNi SAA exhibits simultaneously improved activity (TOF value: 4293 h− 1) and chemoselectivity toward selective hydrogenation of 4-nitrostyrene to 4-aminostyrene (yield: >99%), which is, to the best of our knowledge, the highest level compared with reported heterogeneous catalysts. In situ experimental researches based on XAFS, FT-IR measurements and theoretical calculations reveal that the Ru–Ni interfacial sites as intrinsic active centers facilitate the preferential cleavage of N–O bond in nitro group with a decreased energy barrier by 0.35 eV. In addition, the Ru–Ni synergistic catalysis promotes the formation of intermediates (C8H7NO* and C8H7NOH*) and accelerates the rate-determining step (hydrogenation of C8H7NOH*), resulting in the extraordinary activity and chemoselectivity toward nitroarenes hydrogenation.

scholarly journals A general strategy for preparing pyrrolic-N4 type single-atom catalysts via pre-located isolated atoms

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junjie Li ◽  
Ya-fei Jiang ◽  
Qi Wang ◽  
Cong-Qiao Xu ◽  
Duojie Wu ◽  
...  
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Rational Design ◽  
Catalytic Performance ◽  
Single Atom ◽  
General Strategy ◽  
New Findings ◽  
Synthesis Strategy ◽  
Structure Density ◽  
Application Fields

AbstractSingle-atom catalysts (SACs) have been applied in many fields due to their superior catalytic performance. Because of the unique properties of the single-atom-site, using the single atoms as catalysts to synthesize SACs is promising. In this work, we have successfully achieved Co1 SAC using Pt1 atoms as catalysts. More importantly, this synthesis strategy can be extended to achieve Fe and Ni SACs as well. X-ray absorption spectroscopy (XAS) results demonstrate that the achieved Fe, Co, and Ni SACs are in a M1-pyrrolic N4 (M= Fe, Co, and Ni) structure. Density functional theory (DFT) studies show that the Co(Cp)2 dissociation is enhanced by Pt1 atoms, thus leading to the formation of Co1 atoms instead of nanoparticles. These SACs are also evaluated under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and the nature of active sites under HER are unveiled by the operando XAS studies. These new findings extend the application fields of SACs to catalytic fabrication methodology, which is promising for the rational design of advanced SACs.

scholarly journals Single-atom catalyst: a rising star for green synthesis of fine chemicals

2018 ◽  
Vol 5 (5) ◽  
pp. 653-672 ◽  
Author(s):  
Leilei Zhang ◽  
Yujing Ren ◽  
Wengang Liu ◽  
Aiqin Wang ◽  
Tao Zhang
Keyword(s):  
Green Synthesis ◽  
Active Sites ◽  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Catalytic Performance ◽  
Research Area ◽  
Single Atom ◽  
Metal Species ◽  
Future Research ◽  
Fine Chemicals

Abstract The green synthesis of fine chemicals calls for a new generation of efficient and robust catalysts. Single-atom catalysts (SACs), in which all metal species are atomically dispersed on a solid support, and which often consist of well-defined mononuclear active sites, are expected to bridge homogeneous and heterogeneous catalysts for liquid-phase organic transformations. This review summarizes major advances in the SAC-catalysed green synthesis of fine chemicals in the past several years, with a focus on the catalytic activity, selectivity and reusability of SACs in various organic reactions. The relationship between catalytic performance and the active site structure is discussed in terms of the valence state, coordination environment and anchoring chemistry of single atoms to the support, in an effort to guide the rational design of SACs in this special area, which has traditionally been dominated by homogeneous catalysis. Finally, the challenges remaining in this research area are discussed and possible future research directions are proposed.

scholarly journals Engineering the Coordination Sphere of Isolated Active Sites to Explore the Intrinsic Activity in Single-Atom Catalysts

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Xin Wu ◽  
Huabin Zhang ◽  
Shouwei Zuo ◽  
Juncai Dong ◽  
Yang Li ◽  
...  
Keyword(s):  
Metallic Nanoparticles ◽  
Active Sites ◽  
Catalytic Performance ◽  
Research Field ◽  
Single Atom ◽  
Intrinsic Activity ◽  
Future Research ◽  
Structure Property ◽  
Coordination Spheres ◽  
Further Development

AbstractReducing the dimensions of metallic nanoparticles to isolated, single atom has attracted considerable attention in heterogeneous catalysis, because it significantly improves atomic utilization and often leads to distinct catalytic performance. Through extensive research, it has been recognized that the local coordination environment of single atoms has an important influence on their electronic structures and catalytic behaviors. In this review, we summarize a series of representative systems of single-atom catalysts, discussing their preparation, characterization, and structure–property relationship, with an emphasis on the correlation between the coordination spheres of isolated reactive centers and their intrinsic catalytic activities. We also share our perspectives on the current challenges and future research promises in the development of single-atom catalysis. With this article, we aim to highlight the possibility of finely tuning the catalytic performances by engineering the coordination spheres of single-atom sites and provide new insights into the further development for this emerging research field.

scholarly journals Directing reaction pathways via in situ control of active site geometries in PdAu single-atom alloy catalysts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mengyao Ouyang ◽  
Konstantinos G. Papanikolaou ◽  
Alexey Boubnov ◽  
Adam S. Hoffman ◽  
Georgios Giannakakis ◽  
...  
Keyword(s):  
Active Site ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Bimetallic Catalyst ◽  
Theoretical Calculations ◽  
Atomic Scale ◽  
Single Atom ◽  
In Situ Control ◽  
Single Atom Alloy

AbstractThe atomic scale structure of the active sites in heterogeneous catalysts is central to their reactivity and selectivity. Therefore, understanding active site stability and evolution under different reaction conditions is key to the design of efficient and robust catalysts. Herein we describe theoretical calculations which predict that carbon monoxide can be used to stabilize different active site geometries in bimetallic alloys and then demonstrate experimentally that the same PdAu bimetallic catalyst can be transitioned between a single-atom alloy and a Pd cluster phase. Each state of the catalyst exhibits distinct selectivity for the dehydrogenation of ethanol reaction with the single-atom alloy phase exhibiting high selectivity to acetaldehyde and hydrogen versus a range of products from Pd clusters. First-principles based Monte Carlo calculations explain the origin of this active site ensemble size tuning effect, and this work serves as a demonstration of what should be a general phenomenon that enables in situ control over catalyst selectivity.

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