Hydrogen adsorption–desorption and oxide formation–reduction on polycrystalline platinum in unbuffered aqueous solutions

1994 ◽  
Vol 90 (24) ◽  
pp. 3663-3668 ◽  
Author(s):  
Derek Pletcher ◽  
Sotirios Sotiropoulos
Keyword(s):  
Aqueous Solutions ◽  
Hydrogen Adsorption ◽  
Oxide Formation ◽  
Polycrystalline Platinum ◽  
Adsorption Desorption

Hydrogen Adsorption Capacity Investigation of Ni-Co-Al Mixed Oxides

2014 ◽  
Vol 917 ◽  
pp. 360-364 ◽  
Author(s):  
M. Abdus Salam ◽  
Suriati Sufian
Keyword(s):  
Hydrogen Adsorption ◽  
Mixed Oxides ◽  
Textural Properties ◽  
Metal Dispersion ◽  
Temperature Programmed Reduction ◽  
Oxide Formation ◽  
Nickel Cobalt ◽  
Icp Ms ◽  
Temperature Programmed ◽  
Adsorption Desorption

Micro-mesoporous mixed oxides containing nickel, cobalt and aluminum have been synthesized using conventional coprecipitation method. FESEM and HRTEM analyses demonstrated the flower and hexagonal plate-like nanostructured of mixed oxides. Different mixed oxide formation, homogenous metal dispersion, textural properties were investigated using XRD, ICP-MS and BET (N2 adsorption-desorption) techniques. nanostructured mixed oxides exhibited 2.6 wt% hydrogen adsorption that were studied using temperature programmed reduction-adsorption-desorption (H2-TPR/TPD) and thermogravimetric and differential thermal analysis (TGA-DTA) techniques. Investigation corresponds that morphologies, textural properties and surface energy of mixed oxides are important in hydrogen adsorption.

The Adsorption, Desorption, and Exchange Reactions of Oxygen, Hydrogen, and Water on Platinum Surfaces. II. Hydrogen Adsorption, Exchange, and Equilibration

1975 ◽  
Vol 53 (2) ◽  
pp. 298-306 ◽  
Author(s):  
Y. K. Peng ◽  
P. T. Dawson
Keyword(s):  
Hydrogen Adsorption ◽  
Surface Composition ◽  
Co Adsorption ◽  
Exchange Reactions ◽  
Platinum Surface ◽  
Polycrystalline Platinum ◽  
Platinum Surfaces ◽  
Exponential Factors ◽  
Apparent Activation Energies ◽  
Adsorption Desorption

The adsorption, desorption, exchange, and equilibration reactions of hydrogen and deuterium on a platinum filament have been investigated by thermal desorption mass spectrometry. A surface saturated with hydrogen at 120 °K has a coverage 4.2 × 1014 molecules cm−2 and gives desorption spectra with four distinct peaks: β1,(165 °K), β2(220 °K), β3(280 °K), and β4(350 °K). Apparent activation energies and pre-exponential factors were determined for the β2-, β3-, and β4-peaks. For both co-adsorption and sequential adsorption of H2 and D2 the mass 2, 3, and 4 desorption spectra have identical shapes and the gas desorbs at equilibrium throughout. It is concluded that hydrogen adsorbs dissociatively. Exchange and equilibration were studied at 120, 210, and 285 °K by determining the surface composition and isotope distribution after varying fractions of preadsorbed H had been replaced. Following exchange at 120 °K the desorption spectra show a higher D content and a lack of equilibrium in the desorbing gas at low temperature. In most other experiments the mass 2,3, and 4 desorption spectra had identical shapes and the gas desorbed at equilibrium. The results are interpreted by a model which requires that the polycrystalline platinum surface is intrinsically heterogeneous. It appears that different mechanisms are unnecessary to interpret the differences in kinetics observed for exchange and equilibration at low temperatures.

In situ infrared monitoring of hydrogen adsorption/desorption at a germanium electrode

1999 ◽  
Vol 427-428 ◽  
pp. 184-189 ◽  
Author(s):  
F. Maroun ◽  
F. Ozanam ◽  
J.-N. Chazalviel
Keyword(s):  
Hydrogen Adsorption ◽  
Infrared Monitoring ◽  
Adsorption Desorption

scholarly journals Atmospheric Air Plasma Treated SnS Films: An Efficient Electrocatalyst for HER

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 462 ◽  
Author(s):  
Po-Chia Huang ◽  
Sanjaya Brahma ◽  
Po-Yen Liu ◽  
Jow-Lay Huang ◽  
Sheng-Chang Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Hydrogen Adsorption ◽  
High Plasma ◽  
Air Plasma ◽  
Atmospheric Air ◽  
Onset Potential ◽  
Active Edge ◽  
Sns Thin Films ◽  
P Type ◽  
Adsorption Desorption

Here, we demonstrate the enhanced water-splitting performance (I = 10 mA/cm2, Tafel slope = 60 mV/dec, onset potential = −80 mV) of atmospheric air plasma treated (AAPT) SnS thin films by the hydrogen evolution reaction (HER). The as prepared SnS films were subjected to Atmospheric Air Plasma Treatment (AAPT) which leads to formation of additional phases of Sn and SnO2 at plasma powers of 150 W and 250 W, respectively. The AAPT treatment at 150 W leads to the evaporation of the S atoms as SO2 generates a number of S-vacancies and Sn active edge sites over the surface of the SnS thin film. S-vacancies also create Sn active edge sites, surface p-type pinning that tunes the suitable band positions, and a hydrophilic surface which is beneficial for hydrogen adsorption/desorption. At high plasma power (250 W), the surface of the SnS films becomes oxidized and degrades the HER performance. These results demonstrate that AAPT (150 W) is capable of improving the HER performance of SnS thin films and our results indicate that SnS thin films can work as efficient electrocatalysts for HER.

Synthesis of Novel Core-Shell Structured Hydroxyapatite/Meso-Silica for Removal of Methylene Blue from Aqueous Solutions

2012 ◽  
Vol 463-464 ◽  
pp. 543-547 ◽  
Author(s):  
Cheng Feng Li ◽  
Xiao Lu Ge ◽  
Shu Guang Liu ◽  
Fei Yu Liu
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Core Shell ◽  
Adsorption Desorption

Core-shell structured hydroxyapatite (HA)/meso-silica was prepared and used as absorbance of methylene blue (MB). HA/meso-silica was synthesized in three steps: preparation of nano-sized HA by wet precipitation method, coating of dense silica and deposition of meso-silica shell on HA. As-received samples were characterized by Fourier transformed infare spectra, small angle X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. A wormhole framework mesostructure was found for HA/meso-silica. The specific surface area and pore volume were 128 m2•g-1 and 0.36 cm3•g-1, respectively. From the adsorption isotherm, HA/meso-silica with the great specific surface area exhibited a prominent adsorption capacity of MB (134.0 mg/g) in comparison with bare HA (0 mg/g). This study might shed light on surface modification of conventional low-cost adsorbents for removal of organic pollutants from aqueous solutions.

scholarly journals Kinetic and Equilibrium Studies on the Zinc Adsorption-desorption Characteristics of Some Promising Biochars in Aqueous Solutions

2021 ◽  
Author(s):  
Masoumeh Faryadi Shahgoli ◽  
Adel Reyhanitabar ◽  
Nosratollah Najafi ◽  
Shahin Oustan
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Rice Straw ◽  
Pyrolysis Temperature ◽  
Ph Effect ◽  
Solution Ph ◽  
Equilibrium Studies ◽  
Batch Technique ◽  
Adsorption Desorption ◽  
Zinc Adsorption

Abstract The present research aimed at investigating zinc (Zn) sorption capacity of the biochars derived from apple wood (WB) and rice straw (RB) feedstocks at two 300 and 600°C pyrolysis temperatures (WB300, WB600, RB300 and RB600, respectively) in aqueous solutions. Kinetic and equilibrium sorption experiments were conducted via batch technique. In equilibrium adsorption experiments, the study used the concentration range of 5-200 mg Zn L− 1 and focused on the solution pH effect on Zn adsorption in biochars under the following conditions: unadjusted and adjusted pH (4 and 6) and three ionic strength levels (0.01, 0.03, 0.1 M KNO3). Zinc desorption experiments were conducted under all above mentioned conditions but without pH adjustment at five separate stages. Kinetic data analysis indicated that Zn adsorption in biochars reached the near steady state within 24 hours with the sorption rate order of WB300 < WB600 < RB300 < RB600. The best fitness was superior to both Elovich and exponential rate models. Also, Zn adsorption isotherms in the studied biochars were shown to fit quite well to Langmuir, Freundlich and Dubinin-Radushkevich models. Zn sorption maxima were found to be 4.3, 16.4, 17.9 and 33.3 mg g− 1, on average, for WB300, WB600, RB300, and RB600, respectively. The initial increased pH solution from 4 to 6 caused an increase in Zn adsorption in RB600, RB300 and WB600, however the sorption maxima in WB300 was detected at pH 4. The rise in solution ionic strength from 0.01 M to 0.1 M dropped the Zn adsorption capacity in all the studied biochars. Findings suggested that rice straw derived biochars showed a better performance than woody biochars in Zn sorption and retention from aqueous solutions. In addition, this ability increased with increasing pyrolysis temperature in both types of biochars. Finally, the study revealed that rice straw biochars, produced at high pyrolysis temperatures, can serve as economical and efficient absorbents for Zn removal from aqueous solutions.

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