scholarly journals Highly porous Co-doped NiO nanorods: facile hydrothermal synthesis and electrocatalytic oxygen evolution properties

2021 ◽  
Vol 8 (9) ◽  
pp. 202352
Author(s):  
Nguyen Duc Cuong ◽  
Tien D. Tran ◽  
Quyen T. Nguyen ◽  
Ho Van Minh Hai ◽  
Tran Thai Hoa ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Oxygen Evolution ◽  
Alkaline Medium ◽  
Active Sites ◽  
High Specific Surface Area ◽  
High Porosity ◽  
Metal Oxide Nanostructures ◽  
Highly Porous ◽  
Co Doped

Highly porous 3d transition metal oxide nanostructures are opening up the exciting area of oxygen evolution reaction (OER) catalysts in alkaline medium thanks to their good thermal and chemical stability, excellent physiochemical properties, high specific surface area and abundant nanopores. In this paper, highly porous Co-doped NiO nanorods were successfully synthesized by a simple hydrothermal method. The porous rod-like nanostructures were preserved with the added cobalt dopant ranging from 1 to 5 at% but were broken into aggregated nanoparticles at higher concentrations of additional cobalt. The catalytic activity of Co-doped NiO nanostructures for OER in an alkaline medium was assayed. The 5%Co-NiO sample showed a drastically enhanced activity. This result could originate from the combination of advantageous characteristics of highly porous NiO nanorods such as large surface area and high porosity as well as the important role of Co dopant that could provide more catalytic active sites, leading to an enhanced catalytic activity of the nanocatalyst.

Interface modulation of a layer-by-layer electrodeposited FexCo(1−x)P/NiP@CC heterostructure for high-performance oxygen evolution reaction

2020 ◽  
Vol 4 (4) ◽  
pp. 1863-1874 ◽  
Author(s):  
Bezawit Z. Desalegn ◽  
Harsharaj S. Jadhav ◽  
Jeong Gil Seo
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Oxygen Evolution ◽  
Alkaline Medium ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
High Performance ◽  
Layer By Layer ◽  
Interface Modulation

Heterostructuring assisted trimetallic transition metal phoshide with in situ generated active sites, exhibits superior catalytic activity towards oxygen evolution reaction in alkaline medium.

Bifunctional electrocatalysts of MOF-derived Co–N/C on bamboo-like MnO nanowires for high-performance liquid- and solid-state Zn–air batteries

2018 ◽  
Vol 6 (20) ◽  
pp. 9716-9722 ◽  
Author(s):  
Ya-Nan Chen ◽  
Yibo Guo ◽  
Huijuan Cui ◽  
Zhaojun Xie ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Solid State ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
High Performance ◽  
High Specific Surface Area ◽  
Bifunctional Electrocatalysts ◽  
Nanowire Structure

MnO@Co–N/C composites were fabricated with excellent bifunctional catalytic activity and outstanding performance for both liquid- and solid-state Zn–air batteries. The excellent electrocatalytic activities are attributed to the unique 1D nanowire structure with abundant Co–Nx active sites and a high specific surface area.

scholarly journals Study of deactivation in mesocellular foam carbon (MCF-C) catalyst used in gas-phase dehydrogenation of ethanol

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yoottapong Klinthongchai ◽  
Seeroong Prichanont ◽  
Piyasan Praserthdam ◽  
Bunjerd Jongsomjit
Keyword(s):  
Catalytic Activity ◽  
Pore Size ◽  
Gas Phase ◽  
Surface Area ◽  
Active Sites ◽  
Operating Temperature ◽  
Coke Formation ◽  
Ethanol Conversion ◽  
Deactivation Of Catalyst ◽  
Dehydrogenation Of Ethanol

AbstractMesocellular foam carbon (MCF-C) is one the captivating materials for using in gas phase dehydrogenation of ethanol. Extraordinary, enlarge pore size, high surface area, high acidity, and spherical shape with interconnected pore for high diffusion. In contrary, the occurrence of the coke is a majority causes for inhibiting the active sites on catalyst surface. Thus, this study aims to investigate the occurrence of the coke to optimize the higher catalytic activity, and also to avoid the coke formation. The MCF-C was synthesized and investigated using various techniques. MCF-C was spent in gas-phase dehydrogenation of ethanol under mild conditions. The deactivation of catalyst was investigated toward different conditions. Effects of reaction condition including different reaction temperatures of 300, 350, and 400 °C on the deactivation behaviors were determined. The results indicated that the operating temperature at 400 °C significantly retained the lowest change of ethanol conversion, which favored in the higher temperature. After running reaction, the physical properties as pore size, surface area, and pore volume of spent catalysts were decreased owing to the coke formation, which possibly blocked the pore that directly affected to the difficult diffusion of reactant and caused to be lower in catalytic activity. Furthermore, a slight decrease in either acidity or basicity was observed owing to consumption of reactant at surface of catalyst or chemical change on surface caused by coke formation. Therefore, it can remarkably choose the suitable operating temperature to avoid deactivation of catalyst, and then optimize the ethanol conversion or yield of acetaldehyde.

The Influence of Fe/Al Molar Ratio on Microreactor-Based Catalyst Preparation and Carbon Nanotube Preparation

2021 ◽  
Vol 1036 ◽  
pp. 130-136
Author(s):  
Ting Qun Tan ◽  
Lei Geng ◽  
Yan Lin ◽  
Yan He
Keyword(s):  
Carbon Nanotubes ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Small Diameter ◽  
High Specific Surface Area ◽  
Detection Methods ◽  
Molar Ratio ◽  
High Catalytic Activity

In order to prepare carbon nanotubes with high specific surface area, small diameter, low resistivity, high purity and high catalytic activity, the Fe-Mo/Al2O3 catalyst was prepared based on the microreactor. The influence of different Fe/Al molar ratios on the catalyst and the carbon nanotubes prepared was studied through BET, SEM, TEM and other detection methods. Studies have shown that the pore structure of the catalyst is dominated by slit pores at a lower Fe/Al molar ratio. The catalytic activity is the highest when the Fe/Al molar ratio is 1:1, reaching 74.1%. When the Fe/Al molar ratio is 1:2, the catalyst has a higher specific surface area, the maximum pore size is 8.63 nm, and the four-probe resistivity and ash content of the corresponding carbon nanotubes are the lowest. The higher the proportion of aluminum, the higher the specific surface area of the catalyst and the carbon nanotubes, and the finer the diameter of the carbon nanotubes, which gradually tends to relax. The results show that when the Fe/Al molar ratio is 1:2, although the catalytic activity of the catalyst is not the highest, the carbon nanotubes prepared have the best performance.

scholarly journals Mononuclear Fe in N-doped carbon: computational elucidation of active sites for electrochemical oxygen reduction and oxygen evolution reactions

2020 ◽  
Vol 10 (4) ◽  
pp. 1006-1014 ◽  
Author(s):  
Rui Shang ◽  
Stephan N. Steinmann ◽  
Bo-Qing Xu ◽  
Philippe Sautet
Keyword(s):  
Oxygen Reduction ◽  
Oxygen Evolution ◽  
Electrostatic Potential ◽  
First Principles ◽  
Active Sites ◽  
High Potential ◽  
Major Influence ◽  
Co Doped ◽  
Electrochemical Oxygen

First principles simulations show that in Fe and N co-doped carbon, Fe coordination controls the activity for oxygen reduction and oxygen evolution reactions, and that including the electrostatic potential has a major influence at high potential.

scholarly journals Ultrathin Co–Fe hydroxide nanosheet arrays for improved oxygen evolution during water splitting

RSC Advances ◽  
2017 ◽  
Vol 7 (37) ◽  
pp. 22818-22824 ◽  
Author(s):  
Tingting Zhou ◽  
Zhen Cao ◽  
Heng Wang ◽  
Zhen Gao ◽  
Long Li ◽  
...  
Keyword(s):  
Surface Area ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Three Dimensional ◽  
Fe Doping ◽  
Nanosheet Arrays ◽  
Fe Hydroxide

The Fe-doping of hierarchical Co hydroxide nanosheet arrays (CoyFe1−y(OH)x NSAs) integrated on a three-dimensional electrode is shown to contribute to both increasing the available surface area and number of active sites.

scholarly journals Facile Synthesis of Carbon Cloth Supported Cobalt Carbonate Hydroxide Hydrate Nanoarrays for Highly Efficient Oxygen Evolution Reaction

2021 ◽  
Vol 9 ◽  
Author(s):  
Yubing Yan
Keyword(s):  
Electron Microscopy ◽  
Oxygen Evolution ◽  
Current Density ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Carbon Cloth ◽  
High Porosity ◽  
Cobalt Carbonate ◽  
Carbonate Hydroxide ◽  
Hydroxide Hydrate

Developing efficient and low-cost replacements for noble metals as electrocatalysts for the oxygen evolution reaction (OER) remain a great challenge. Herein, we report a needle-like cobalt carbonate hydroxide hydrate (Co(CO3)0.5OH·0.11H2O) nanoarrays, which in situ grown on the surface of carbon cloth through a facile one-step hydrothermal method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations demonstrate that the Co(CO3)0.5OH nanoarrays with high porosity is composed of numerous one-dimensional (1D) nanoneedles. Owing to unique needle-like array structure and abundant exposed active sites, the Co(CO3)0.5OH@CC only requires 317 mV of overpotential to reach a current density of 10 mA cm−2, which is much lower than those of Co(OH)2@CC (378 mV), CoCO3@CC (465 mV) and RuO2@CC (380 mV). For the stability, there is no significant attenuation of current density after continuous operation 27 h. This work paves a facile way to the design and construction of electrocatalysts for the OER.

scholarly journals Template-free synthesis of mesoporous manganese oxides with catalytic activity in the oxygen evolution reaction

2017 ◽  
Vol 1 (4) ◽  
pp. 780-788 ◽  
Author(s):  
Suoyuan Lian ◽  
Michelle P. Browne ◽  
Carlota Domínguez ◽  
Serban N. Stamatin ◽  
Hugo Nolan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Activity ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Water Oxidation ◽  
Manganese Oxides ◽  
Template Free ◽  
Highly Porous

Solvothermally synthesised MnCO3 leads to template-free formation of highly porous, defect-rich MnO2 with high activity in water oxidation.

scholarly journals Surface and Catalytic Properties of γ-Irradiated Cr2O3/Al2O3 Solids

1997 ◽  
Vol 15 (6) ◽  
pp. 465-476 ◽  
Author(s):  
G.A. El-Shobaky ◽  
A.M. Ghozza ◽  
G.M. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Surface Area ◽  
Pore Volume ◽  
Active Sites ◽  
Catalytic Properties ◽  
Total Pore Volume ◽  
Bet Surface Area ◽  
Two Samples ◽  
Γ Rays

Two samples of Cr2O3/Al2O3 were prepared by mixing a known mass of finely powdered Al(OH)3 with a calculated amount of CrO3 solid followed by drying at 120°C and calcination at 400°C. The amounts of chromium oxide employed were 5.66 and 20 mol% Cr2O3, respectively. The calcined solid specimens were then treated with different doses of γ-rays (20–160 Mrad). The surface and catalytic properties of the different irradiated solids were investigated using nitrogen adsorption at −196°C and the catalysis of CO oxidation by O2 at 300–400°C. The results revealed that γ-rays brought about a slight decrease in the BET surface area, SBET (15%), and in the total pore volume, Vp (20%), of the adsorbent containing 5.66 mol% Cr2O3. The same treatment increased the total pore volume, Vp (36%), and the mean pore radius, r̄ (43%), of the other adsorbent sample without changing its BET surface area. The catalytic activities of both catalyst samples were found to increase as a function of dose, reaching a maximum value at 80–160 Mrad and 40 Mrad for the solids containing 5.66 and 20 mol% Cr2O3, respectively. The maximum increase in the catalytic activity measured at 300°C was 59% and 100% for the first and second catalyst samples, respectively. The induced effect of γ-irradiation on the catalytic activity was an increase in the concentration of catalytically active sites taking part in chemisorption and in the catalysis of CO oxidation by O2 without changing their energetic nature. This was achieved by a progressive removal of surface hydroxy groups during the irradiation process.

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