scholarly journals Acceptorless dehydrogenation and hydrogenation of N- and O-containing compounds on Pd3Au1(111) facets

2020 ◽  
Vol 6 (27) ◽  
pp. eabb3831 ◽  
Author(s):  
Xinjiang Cui ◽  
Zhangjun Huang ◽  
Antoine P. van Muyden ◽  
Zhaofu Fei ◽  
Tao Wang ◽  
...  
Keyword(s):  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Unmet Need ◽  
Multiwall Carbon Nanotubes ◽  
Density Functional Theory Calculations ◽  
High Catalytic Activity ◽  
Catalytic Dehydrogenation ◽  
Transmission Electron Microscopy Analysis ◽  
Molar Ratios ◽  
Highly Active

Catalytic dehydrogenation and hydrogenation of amines and alcohols are important in the synthesis of fine chemicals. Despite several efficient homogeneous catalysts having been identified, highly active heterogeneous catalysts remain elusive, although they would meet an unmet need. Here, we show that bimetallic Pd-Au nanoparticles with Pd-to-Au molar ratios of 3:1 immobilized on multiwall carbon nanotubes (Pd3Au1/CNT) display high catalytic activity in the oxidant-free and acceptorless dehydrogenation and hydrogenation of N- and O-containing heterocyclic compounds, amines/imines, and alcohols/ketones. Transmission electron microscopy analysis demonstrates the preferential exposure of Pd3Au1(111) facets on the Pd3Au1/CNT catalyst. Mechanistic insights combining experimental data with density functional theory calculations reveal that the Pd3Au1(111) surface enhances both dehydrogenation and hydrogenation reactions and provides a rationale for the observed enhancements.

scholarly journals Highly active and selective oxygen reduction to H2O2 on boron-doped carbon for high production rates

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yang Xia ◽  
Xunhua Zhao ◽  
Chuan Xia ◽  
Zhen-Yu Wu ◽  
Peng Zhu ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Density Functional ◽  
High Selectivity ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Production Rates ◽  
Practical Applications ◽  
Highly Active ◽  
Boron Doped ◽  
Oxidized Carbon

AbstractOxygen reduction reaction towards hydrogen peroxide (H2O2) provides a green alternative route for H2O2 production, but it lacks efficient catalysts to achieve high selectivity and activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm−2) while maintaining high H2O2 selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H2O2 activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H2O2 solutions with high selectivity (up to 95%) and high H2O2 partial currents (up to ~400 mA cm−2), illustrating the catalyst’s great potential for practical applications in the future.

Towards highly active heterogeneous catalysts via a sequential noncovalent bonding strategy

2021 ◽  
Author(s):  
Ruixue Wang ◽  
Ying Yue ◽  
Huiying Wei ◽  
Jinxin Guo ◽  
Yanzhao Yang
Keyword(s):  
Catalytic Activity ◽  
Heterogeneous Catalysts ◽  
High Catalytic Activity ◽  
Synthetic Route ◽  
Surface Ligands ◽  
Highly Active ◽  
Noncovalent Bonding ◽  
Excellent Stability

Here, a novel synthetic route of ceria-based nanocatalysts with high catalytic activity and excellent stability was constructed by utilizing function groups from surface ligands. The surface of ceria nanorods were...

scholarly journals Role of hydroxylation for the atomic structure of a non-polar vicinal zinc oxide

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Elin Grånäs ◽  
Michael Busch ◽  
Björn Arndt ◽  
Marcus Creutzburg ◽  
Guilherme Dalla Lana Semione ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Density Functional ◽  
Chemical Properties ◽  
Density Functional Theory Calculations ◽  
Atomic Scale ◽  
Water Dissociation ◽  
Oxide Surface ◽  
Highly Active ◽  
Potential Applications ◽  
Physical And Chemical

AbstractFrom the catalytic, semiconducting, and optical properties of zinc oxide (ZnO) numerous potential applications emerge. For the physical and chemical properties of the surface, under-coordinated atoms often play an important role, necessitating systematic studies of their influence. Here we study the vicinal ZnO($$10\bar{1}4$$ 10 1 ¯ 4 ) surface, rich in under-coordinated sites, using a combination of several experimental techniques and density functional theory calculations. We determine the atomic-scale structure and find the surface to be a stable, long-range ordered, non-polar facet of ZnO, with a high step-density and uniform termination. Contrary to an earlier suggested nano-faceting model, a bulk termination fits much better to our experimental observations. The surface is further stabilized by dissociatively adsorbed H2O on adjacent under-coordinated O- and Zn-atoms. The stabilized surface remains highly active for water dissociation through the remaining under-coordinated Zn-sites. Such a vicinal oxide surface is a prerequisite for future adsorption studies with atomically controlled local step and terrace geometry.

scholarly journals Confined catalysis under two-dimensional materials

2017 ◽  
Vol 114 (23) ◽  
pp. 5930-5934 ◽  
Author(s):  
Haobo Li ◽  
Jianping Xiao ◽  
Qiang Fu ◽  
Xinhe Bao
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Catalyst Surface ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Surface Reactivity ◽  
Monolayer Graphene ◽  
2D Material ◽  
2D Space

Confined microenvironments formed in heterogeneous catalysts have recently been recognized as equally important as catalytically active sites. Understanding the fundamentals of confined catalysis has become an important topic in heterogeneous catalysis. Well-defined 2D space between a catalyst surface and a 2D material overlayer provides an ideal microenvironment to explore the confined catalysis experimentally and theoretically. Using density functional theory calculations, we reveal that adsorption of atoms and molecules on a Pt(111) surface always has been weakened under monolayer graphene, which is attributed to the geometric constraint and confinement field in the 2D space between the graphene overlayer and the Pt(111) surface. A similar result has been found on Pt(110) and Pt(100) surfaces covered with graphene. The microenvironment created by coating a catalyst surface with 2D material overlayer can be used to modulate surface reactivity, which has been illustrated by optimizing oxygen reduction reaction activity on Pt(111) covered by various 2D materials. We demonstrate a concept of confined catalysis under 2D cover based on a weak van der Waals interaction between 2D material overlayers and underlying catalyst surfaces.

scholarly journals The nature of active sites for carbon dioxide electroreduction over oxide-derived copper catalysts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongfang Cheng ◽  
Zhi-Jian Zhao ◽  
Gong Zhang ◽  
Piaoping Yang ◽  
Lulu Li ◽  
...  
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Density Functional Theory Calculations ◽  
Copper Catalysts ◽  
Functional Theory ◽  
Surface Models ◽  
Cu Catalysts ◽  
Intense Debate

AbstractThe active sites for CO2 electroreduction (CO2R) to multi-carbon (C2+) products over oxide-derived copper (OD-Cu) catalysts are under long-term intense debate. This paper describes the atomic structure motifs for product-specific active sites on OD-Cu catalysts in CO2R. Herein, we describe realistic OD-Cu surface models by simulating the oxide-derived process via the molecular dynamic simulation with neural network (NN) potential. After the analysis of over 150 surface sites through NN potential based high-throughput testing, coupled with density functional theory calculations, three square-like sites for C–C coupling are identified. Among them, Σ3 grain boundary like planar-square sites and convex-square sites are responsible for ethylene production while step-square sites, i.e. n(111) × (100), favor alcohols generation, due to the geometric effect for stabilizing acetaldehyde intermediates and destabilizing Cu–O interactions, which are quantitatively demonstrated by combined theoretical and experimental results. This finding provides fundamental insights into the origin of activity and selectivity over Cu-based catalysts and illustrates the value of our research framework in identifying active sites for complex heterogeneous catalysts.

scholarly journals Water-Involved Methane Selective Catalytic Oxidation by Dioxygen over Copper-Zeolites

2020 ◽  
Author(s):  
Lanlan Sun ◽  
Yu Wang ◽  
Chuanming Wang ◽  
Zaiku Xie ◽  
Naijia Guan ◽  
...  
Keyword(s):  
Catalytic Oxidation ◽  
Selective Oxidation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
High Catalytic Activity ◽  
Oxidation Of Methane ◽  
Selective Catalytic Oxidation ◽  
Catalyst Temperature ◽  
Temperature Programmed ◽  
Space Time Yield

<p>The selective oxidation of methane to methanol is a dream reaction of direct methane functionalization, which remains a key challenge in catalysis and a hot issue of controversy. Herein, we report the water-involved methane selective catalytic oxidation by dioxygen over copper-zeolites. At 573 K, a state-of-the-art methanol space-time yield of 543 mmol/mol<sub>Cu</sub>/h with methanol selectivity of 91 % is achieved with Cu-CHA catalyst. Temperature-programmed surface reactions with isotope labelling determine water as the dominating oxygen and hydrogen source of hydroxyl in methanol while dioxygen participates in the reaction <a></a><a>through reducing to water</a>. Spectroscopic analyses reveal the fast redox cycle of Cu<sup>2+</sup>-Cu<sup>+</sup>-Cu<sup>2+</sup> during methane selective oxidation, which is closely related to the high catalytic activity of Cu-CHA. Density functional theory calculations suggest that both CuOH monomer and dimer in Cu-CHA can catalyze the selective oxidation of methane to methanol with Cu-OOH as the key reaction intermediate, and meanwhile, various copper sites undergo interconversion under reaction conditions.<br></p>

Enhanced Nucleophilicity and Depressed Electrophilicity of Peroxide by Zinc(II), Aluminum(III) and Lanthanum(III) Ions

2001 ◽  
Vol 56 (1-2) ◽  
pp. 138-143 ◽  
Author(s):  
Satoshi Nishino ◽  
Teruyuki Kobayashi ◽  
Hideaki Matsushima ◽  
Tadashi Tokii ◽  
Yuzo Nishid
Keyword(s):  
Dna Cleavage ◽  
Density Functional ◽  
Thiobarbituric Acid ◽  
Density Functional Theory Calculations ◽  
Thiobarbituric Acid Reactive Substance ◽  
Cleavage Reaction ◽  
Functional Theory ◽  
Reactive Substance ◽  
Highly Active ◽  
Hydrolytic Mechanism

Abstract The binuclear zinc(II) complex, [Zn2 (HPTP)(CH3 COO)]2+ was found highly active to cleave DNA (double-strand super-coiled DNA, pBR322 and φχ174) in the presence of hy­drogen peroxide. However, no TBARS (2-thiobarbituric acid reactive substance) formation was detected in a solution containing 2 -deoxyribose (or 2′-deoxyguanosine, etc); where (HPTP) represents N,N,N′-N′-tetrakis(2-pyridylmethyl)-1,3-diamino-2-propanol. These facts imply that DNA cleavage reaction by the binuclear Zn(II)/H2O2 system should be due to a hydrolytic mechanism, which may be attributed to the enhanced nucleophilicity but depressed electrophilicity of the peroxide ion coordinated to the zinc(II) ion. DFT (density-functional theory) calculations on the peroxide adduct of monomeric zinc(II) have supported the above consideration. Similar DFT calculations on the peroxide adducts of the Al(III) and La(III) compounds have revealed that electrophilicity of the peroxide ion in these com­ pounds is strongly reduced. This gives an important information to elucidate the fact that La3+ can enhance the growth of plants under certain conditions.

scholarly journals Methane Conversion over C2N-Supported Fe2 Dimers

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 973
Author(s):  
Haihong Meng ◽  
Bing Han ◽  
Fengyu Li ◽  
Jingxiang Zhao
Keyword(s):  
Density Functional ◽  
Value Added ◽  
Density Functional Theory Calculations ◽  
Catalytic Conversion ◽  
High Energy ◽  
Raw Material ◽  
Oxidation Reactions ◽  
Highly Active ◽  
Hydrocarbon Resource ◽  
Conversion Of Methane

Methane is a vast hydrocarbon resource around the globe that has the potential to replace petroleum as a raw material and energy source. Therefore, the catalytic conversion of methane into high value-added chemicals is significantly important for the utilization of this hydrocarbon resource. However, this is a great challenge due to the high-energy input required to overcome the reaction barrier. Herein, a highly active catalytic conversion process of methane on an iron dimer anchored on a two-dimensional (2D) C2N monolayer (Fe2@C2N) is reported. Density functional theory calculations reveal that the superior properties of Fe2@C2N can be attributed to the formation of the Fe-O-Fe intermediate with H2O2 as the O-donor molecule, which facilitates the formation of methyl radicals and promotes the conversion of methane. This finding could pave the way toward highly efficient non-precious metal catalysts for methane oxidation reactions.

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