High performance ozone decomposition spinel (Mn,Co)3O4 catalyst accelerating the rate-determining step

ABSTRACTOrganometallic precursors with low decomposition temperatures are essential in the fabrication of high performance mercury cadmium telluride (Hg1-xCdxTe) infrared detectors by pyrolytic and photolytic metal-organic chemical vapor deposition (MOCVD). Film growth temperature is governed by the relative stability and/or reactivity of the organotellurium precursor, which is determined by the strength of the Te-C bonds. Since the rate-determining step in the pyrolysis of organometallic compounds involves bond breaking and free radical formation, we have concentrated on the synthesis of a variety of organotellurium precursors with substituents that possess low activation energies for the formation of hydrocarbon free radicals. The synthesis, characterization, and properties of methylallyltelluride, ethylallyltelluride, isopropylallyltelluride, tertiarybutylallyl-telluride, methylbenzyltelluride, and methylpentadienyltelluride are reported. These unsymmetrical tellurides were characterized by 1H, 13 C, and 125Te NMR spectroscopy. The potential applicability of these organotellurium precursors to lower film-growth temperatures in MOCVD is discussed.

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

10.21203/rs.3.rs-878026/v1 ◽

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.

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Regulating oxygen vacancy in ultrathin δ-MnO2 nanosheets with superior activity for gaseous ozone decomposition

Environmental Science Nano ◽

10.1039/d1en00149c ◽

2021 ◽

Author(s):

Ranran Cao ◽

Lianxin Li ◽

Pengyi Zhang ◽

Lele Gao ◽

Shaopeng Rong

Keyword(s):

Oxygen Vacancy ◽

Human Health ◽

High Performance ◽

Environmental Problem ◽

Ground Level ◽

The Elderly ◽

Ozone Decomposition ◽

Ozone Pollution ◽

Mno2 Nanosheets ◽

Ground Level Ozone

Ground-level ozone pollution is an environmental problem worldwide, which is hazardous to human health, especially the elderly, the children and the sensitive. It is a tough challenge to develop high-performance...

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Alkali Cation Effect on CO2 Electroreduction to CO: A Local Colligative Property

10.21203/rs.3.rs-1157577/v1 ◽

2021 ◽

Author(s):

Seung-Jae Shin ◽

Hansol Choi ◽

Stefan Ringe ◽

Da Hye Won ◽

Chang Hyuck Choi ◽

...

Keyword(s):

Interface Design ◽

High Performance ◽

Effective Means ◽

Multiscale Simulation ◽

Reduction Reaction ◽

Cation Effect ◽

Cation Concentration ◽

Rate Determining Step ◽

First Order Kinetics ◽

Co2 Electroreduction

Abstract Converting carbon dioxide (CO2) into valuable products is one of the most important processes for a sustainable society. Especially, the electrochemical CO2 reduction reaction (CO2RR) offers an effective means, but its reaction mechanism is not yet fully understood. Here, we demonstrate that cation-coupled electron transfer (CCET) is a rate-determining step in the CO2RR to carbon monoxide. The first-principles-based multiscale simulation identifies a single cation that coordinates a CO2− intermediate adsorbed on Ag electrode. The CCET is experimentally verified by a collapse of the CO2RR polarization curves upon correcting Nernstianly for a bulk cation concentration. As further confirmation, a kinetic study shows that the CO2RR obeys first-order kinetics on a local cation concentration. Finally, this work unveils that the cation effect on CO2RR originates from the local colligative property, and further highlights the importance of ion-pairing tendency for electrochemical interface design to achieve high-performance CO2 electrolysis.

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High performance cobalt nanoparticle catalysts supported by carbon for ozone decomposition: the effects of the cobalt particle size and hydrophobic carbon support

New Journal of Chemistry ◽

10.1039/d0nj04876c ◽

2021 ◽

Author(s):

Dandan Li ◽

Bingheng Cen ◽

Chentao Fang ◽

Xingyue Leng ◽

Weiyue Wang ◽

...

Keyword(s):

Particle Size ◽

High Performance ◽

Carbon Support ◽

Ozone Decomposition ◽

High Humidity ◽

Cobalt Particle ◽

Nanoparticle Catalysts ◽

Significant Challenge ◽

Gaseous Ozone ◽

Cobalt Nanoparticle

Catalytic gaseous ozone decomposition under high humidity is not only an urgent need but also a significant challenge because of the low stability over the available catalysts.

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Three-Phase Heterojunction NiMo-Based Nano-Needle for Water Splitting at Industrial Alkaline Condition

Nano-Micro Letters ◽

10.1007/s40820-021-00744-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Guangfu Qian ◽

Jinli Chen ◽

Tianqi Yu ◽

Jiacheng Liu ◽

Lin Luo ◽

...

Keyword(s):

Water Splitting ◽

Active Sites ◽

High Performance ◽

Density Functional ◽

High Efficiency ◽

Density Functional Theory Calculations ◽

Intrinsic Activity ◽

Alkaline Condition ◽

Rate Determining Step ◽

Three Phase

AbstractConstructing heterojunction is an effective strategy to develop high-performance non-precious-metal-based catalysts for electrochemical water splitting (WS). Herein, we design and prepare an N-doped-carbon-encapsulated Ni/MoO2 nano-needle with three-phase heterojunction (Ni/MoO2@CN) for accelerating the WS under industrial alkaline condition. Density functional theory calculations reveal that the electrons are redistributed at the three-phase heterojunction interface, which optimizes the adsorption energy of H- and O-containing intermediates to obtain the best ΔGH* for hydrogen evolution reaction (HER) and decrease the ΔG value of rate-determining step for oxygen evolution reaction (OER), thus enhancing the HER/OER catalytic activity. Electrochemical results confirm that Ni/MoO2@CN exhibits good activity for HER (ƞ-10 = 33 mV, ƞ-1000 = 267 mV) and OER (ƞ10 = 250 mV, ƞ1000 = 420 mV). It shows a low potential of 1.86 V at 1000 mA cm−2 for WS in 6.0 M KOH solution at 60 °C and can steadily operate for 330 h. This good HER/OER performance can be attributed to the three-phase heterojunction with high intrinsic activity and the self-supporting nano-needle with more active sites, faster mass diffusion, and bubbles release. This work provides a unique idea for designing high efficiency catalytic materials for WS.

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Nickel Ferrocyanide as High-Performance Next Generation Electrocatalyst for Urea Oxidation

10.21203/rs.3.rs-67358/v1 ◽

2020 ◽

Author(s):

Shi-Kui Geng ◽

Yao Zheng ◽

Shan-Qing Li ◽

Xu Zhao ◽

Jun Hu ◽

...

Keyword(s):

Water Oxidation ◽

High Performance ◽

Environmental Science ◽

Supported Catalysts ◽

Reaction Pathway ◽

Next Generation ◽

Molecular Catalyst ◽

Rate Determining Step ◽

Catalytically Active ◽

Nickel Ferrocyanide

Abstract Urea oxidation, a key process in energy and environmental science, faces challenges because of the insufficient understanding of its mechanism and the lack of efficient catalysts. Here we demonstrate that nickel ferrocyanide (Ni2Fe(CN)6) molecular catalyst supported on Ni form can drive urea oxidation reaction (UOR) with the record electrochemical activity and stability among all supported catalysts reported so far. A combination of kinetics data, in-situ spectroscopic measurements and energy computations suggests a new UOR pathway that delivers such outstanding performance. Different from most studied Ni-based catalysts with NiOOH derivative as a real catalytically active site for UOR, Ni2Fe(CN)6 appears to be a next-generation catalyst able to directly facilitate a two-step reaction pathway involving a critical reaction of intermediate ammonia’s production (on Ni site) and oxidation (on Fe site). Due to the alternative rate-determining step with a more favorable thermal energetics, Ni2Fe(CN)6 broke the limiting activity of the reported so far UOR catalysts. As a result, the UOR process on Ni2Fe(CN)6 can replace conventional water oxidation process in various energy-saving systems for hydrogen and hydrogen peroxide production.

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A High Performance Energy Analyzer for Use in Electron Scanning Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061975 ◽

1969 ◽

Vol 27 ◽

pp. 14-15

Author(s):

A. V. Crewe ◽

M. Isaacson ◽

D. Johnson

Keyword(s):

High Performance ◽

Vertical Plane ◽

Median Plane ◽

Electron Gun ◽

Uniform Field ◽

Loss Mechanism ◽

Electron Scanning Microscopy ◽

Sector Type ◽

Double Focusing ◽

Electron Energy Loss

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).

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Vacuum System to Minimize the Specimen Contamination of High-Performance EM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077967 ◽

1977 ◽

Vol 35 ◽

pp. 68-69

Author(s):

N. Yoshimura ◽

K. Shirota ◽

T. Etoh

Keyword(s):

Electron Microscope ◽

High Speed ◽

High Performance ◽

High Vacuum ◽

Vacuum System ◽

Pump System ◽

Pumping System ◽

Diffusion Pump ◽

Almost All ◽

Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

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