Effect of a Thermal Treatment on the Activity of Carbon-Supported Pt, Pt+W and Pt+Mo Electrocatalysts for Methanol Oxidation Reactions

2001 ◽  
Vol 56 (12) ◽  
pp. 1306-1314 ◽  
Author(s):  
Gülsün Gökağaç ◽  
Jean-Michel Leger
Keyword(s):  
Methanol Oxidation ◽  
Carbon Support ◽  
Hydrogen Gas ◽  
Methanol Oxidation Reaction ◽  
Oxidation Reactions ◽  
X Ray ◽  
In Situ Ftir Spectroscopy ◽  
Transmission Electron ◽  
Heat Treated ◽  
Thermally Treated

Abstract Previous studies on carbon supported Pt, Pt+W and Pt+Mo indicated that Pt+Mo was the most active electrocatalyst at low potentials and that Pt+W has similar properties as pure Pt in methanol oxidation. Those samples were thermally treated at 900 °C in a hydrogen gas atmosphere for 6 hours to observe the effect on metal particle sizes and on their distribution on carbon support. It was found that thermally treated Pt+Mo/XC-72 remains the most active catalyst at all potentials compared to the other heated samples. The heat treatment caused the sintering of small particles leading to a decrease in activity of the catalysts except Pt+Mo/XC-72. The heat treated samples were characterised by voltammetry, X-ray diffraction, transmission electron microscopy and energy dispersive X-ray analysis techniques. The methanol oxidation reaction was followed by in-situ FTIR spectroscopy to identify products and adsorbed species on the surface of electrode.

Carbon Supported Pt+Os Catalysts for Methanol Oxidation

2002 ◽  
Vol 57 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Gülsün Gökağaç ◽  
Brendan J. Kennedy
Keyword(s):  
Methanol Oxidation ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Carbon Support ◽  
Methanol Oxidation Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Metal Metal ◽  
Metal Support

11% Pt/C, 10% Pt + 1%Os/C, 9% Pt + 2%Os/C, 8% Pt + 3%Os/C, 7% Pt + 4%Os/C, 6% Pt + 5%Os/C and 5%Pt + 6% Os/C catalysts have been prepared for methanol oxidation reaction. Transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and cyclic voltammetry have been used to understand the nature of the species present in these catalysts. 7% Pt + 4% Os/C was the most active catalyst, while 8% Pt + 3% Os/C was the least active one. It is found that the metal particle size and distribution on the carbon support, the surface composition and the oxidation states of the metal particles, the metal-metal and metal support interactions are important parameters to define the activity of the catalyst.

A Comparative Study on Ternary Low-Platinum Catalysts with Various Constructions for Oxygen Reduction and Methanol Oxidation Reactions

NANO ◽  
2016 ◽  
Vol 11 (07) ◽  
pp. 1650081 ◽  
Author(s):  
Yan Ni Wu ◽  
Hai Fu Guo ◽  
Peng Hu ◽  
Xiao Peng Xiao ◽  
Zhao Wang Xiao ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Methanol Oxidation ◽  
Reduction Reaction ◽  
Methanol Oxidation Reaction ◽  
Core Shell ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
Structured Catalyst ◽  
Transmission Electron ◽  
One Step

Three types of ternary low-platinum nanocatalysts, alloy PdPtIr/C, core–shell PdPt@PtIr/C and Pd@PtIr/C, have been prepared, and their catalytic behaviors toward methanol oxidation reaction (MOR)/oxygen reduction reaction (ORR) are comparatively investigated via cyclic voltammetry and chronoamperometry analysis in an acidic medium. Through a two-step colloidal technique, the synthesized core–shell structured catalyst PtPd@PtIr/C with alloy core and alloy shell show the best catalytic activity toward MOR and the best poisoning tolerance. The alloy PdPtIr/C catalyst prepared via a one-step colloidal technique exhibits the best performance toward ORR among the three catalysts. All the three catalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and other characterization techniques.

scholarly journals Facile solvothermal synthesis of Pt-Cu nanocatalyst with improved electrocatalytic activity toward methanol oxidation

2019 ◽  
Vol 84 (10) ◽  
pp. 1155-1167
Author(s):  
Muhammad Mehmood ◽  
Muhammad Tariq ◽  
Ayaz Hassan ◽  
Abdul Raziq ◽  
Abdur Rahim ◽  
...  
Keyword(s):  
Methanol Oxidation ◽  
Current Density ◽  
Particle Surface ◽  
Metal Catalyst ◽  
Methanol Oxidation Reaction ◽  
Peak Current Density ◽  
Initial Current ◽  
X Ray ◽  
Binary Metal ◽  
Transmission Electron

A binary metal nanocatalyst of platinum and copper was synthesized using a facile solvothermal process (polyol method). The synthesized catalyst was characterized using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performance of the synthesized carbon supported binary metal catalyst, Pt?Cu/?, toward methanol oxidation reaction was checked and then compared with the commercial Pt/C (ETEK) catalyst, using cyclic voltammetry and chronoamperometric techniques. The Pt?Cu/C catalyst was found to be cubic in shape with indentations on the particle surface, having platinum to copper atomic composition of 4:1, i.e., (Pt4Cu). The peak current density for Pt?Cu/C catalyst recorded as 2.3 mA cm-2 at 0.7 V (vs Ag/AgCl) and 50 mV s-1, was two times higher than the current density of the commercially available Pt/C catalyst (1.16 mA cm-2 at 0.76 V). Moreover, the Pt?Cu/C catalyst was found to be more durable than the commercial Pt/C catalyst, as the Pt?Cu/C retained 89 % of its initial current density, while the commercial Pt/C catalyst retained 65 % of its initial current density after 300 potential cycles.

Direct Observation of Crystalline Ordering In Naturally Graphitized Carbon Produced by Low Grade Metamorphism

1977 ◽  
Vol 35 ◽  
pp. 162-163
Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck
Keyword(s):  
Crystallite Size ◽  
Sedimentary Rocks ◽  
Carbonaceous Material ◽  
Low Grade ◽  
X Ray ◽  
Graphitized Carbon ◽  
Transmission Electron ◽  
Heat Treated ◽  
Commercial Carbon ◽  
Metamorphic Zone

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

scholarly journals Ruling Factors in Cinnamaldehyde Hydrogenation: Activity and Selectivity of Pt-Mo Catalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 362
Author(s):  
Marta Stucchi ◽  
Maela Manzoli ◽  
Filippo Bossola ◽  
Alberto Villa ◽  
Laura Prati
Keyword(s):  
Photoelectron Spectroscopy ◽  
Pt Nanoparticles ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Hydrogenation Catalysts ◽  
Cinnamaldehyde Hydrogenation ◽  
Transmission Electron ◽  
Heat Treated ◽  
Heating Treatment

To obtain selective hydrogenation catalysts with low noble metal content, two carbon-supported Mo-Pt bimetallic catalysts have been synthesized from two different molybdenum precursors, i.e., Na2MoO4 and (NH4)6Mo7O24. The results obtained by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) combined with the presence and strength of acid sites clarified the different catalytic behavior toward cinnamaldehyde hydrogenation. After impregnating the carbon support with Mo precursors, each sample was used either as is or treated at 400 °C in N2 flow, as support for Pt nanoparticles (NPs). The heating treatment before Pt deposition had a positive effect on the catalytic performance. Indeed, TEM analyses showed very homogeneously dispersed Pt NPs only when they were deposited on the heat-treated Mo/C supports, and XPS analyses revealed an increase in both the exposure and reduction of Pt, which was probably tuned by different MoO3/MoO2 ratios. Moreover, the different acid properties of the catalysts resulted in different selectivity.

Trimetallic PtNiCo branched nanocages as efficient and durable bifunctional electrocatalysts towards oxygen reduction and methanol oxidation reactions

2021 ◽  
Author(s):  
hengrui Ma ◽  
Zhiping Zheng ◽  
Hongsheng Zhao ◽  
Cong Shen ◽  
Hanming Chen ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Methanol Oxidation ◽  
Oxidation Reaction ◽  
Reduction Reaction ◽  
Great Promise ◽  
Methanol Oxidation Reaction ◽  
Oxidation Reactions ◽  
Bifunctional Electrocatalysts ◽  
Composition And Structure

Engineering the composition and structure of Pt-based alloy electrocatalysts has exhibited great promise for enhancing activity and durability in oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). However, it...

Magnetization and XRD Studies of Laser Heat Treated SmCo5 Powders

2021 ◽  
Vol 1016 ◽  
pp. 1299-1304
Author(s):  
Naidu Seetala ◽  
Deidre Henderson ◽  
Jumel Jno-Baptiste ◽  
Hao Wen ◽  
Sheng Min Guo
Keyword(s):  
Heat Treatment ◽  
Hydrogen Gas ◽  
Vacuum Furnace ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Particles ◽  
Laser Heat ◽  
Heat Treated ◽  
Xrd Studies ◽  
Hydride Phases

The microstructure and magnetization of SmCo5 micro-particles may be used as feedstock for 3D printing to make miniature strong magnets. Thus, the magnetic response and microstructures of commercially available SmCo5 micro-particles were studied under various heat treatments using a high wattage laser. The magnetization of laser heat treated powders at 50-watt showed an increase in magnetization, while the 75-watt melt showed a little to no change. Unfortunately, the coercivity of both laser heat treated samples decreased significantly. Oxidation during the heat treatment is suspected to result in low coercivity. Purging with argon-gas prior to laser heating showed improved coercivity. To further minimize the oxidation problem a set of SmCo5 powder was reduced prior to laser heat treatment using a constant flow of hydrogen gas while being heated at various temperatures from 100 oC to 400 oC for a period of ~4 hours. The results show that the magnetization generally increases with the temperature, while the coercivity decreases significantly. Another set of SmCo5 was annealed in a vacuum furnace for one hour at temperatures between 200 oC and 400 oC in order to confirm that no hydride phases were formed during reduction. The magnetization and coercivity showed similar variations with annealing temperature to those for the reduced powders confirming that these variations may be due to change in crystal structure rather than formation of hydrides. X-ray Diffraction (XRD) studies were performed to identify the changes in crystal phases.

Nickel nanocrystal/nitrogen-doped carbon composites as efficient and carbon monoxide-resistant electrocatalysts for methanol oxidation reactions

Nanoscale ◽  
2020 ◽  
Vol 12 (42) ◽  
pp. 21687-21694 ◽  
Author(s):  
Na Wu ◽  
Meixu Zhai ◽  
Fei Chen ◽  
Xue Zhang ◽  
Ruihong Guo ◽  
...  
Keyword(s):  
Methanol Oxidation ◽  
Oxidation Reaction ◽  
Low Cost ◽  
Methanol Oxidation Reaction ◽  
Carbon Composites ◽  
Oxidation Reactions ◽  
Facile Synthesis ◽  
Nitrogen Doped ◽  
Cost Efficient ◽  
Nitrogen Doped Carbon

Owing to its facile synthesis, outstanding activity and high stability, Ni/N–C@500 composite is promising as a low-cost, efficient and CO-resistant electrocatalyst for methanol oxidation reaction (MOR).

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