Alkaline media metal-modified

The organic coating at the metal interface is modified chemically by the strong alkaline medium that is generated under the coating. 

Ouf, A.M.A., Abd Elhafeez, A.M., and El-Shafei, A.A. 2008. Ethanol oxidation at metal-zeohte-modified electrodes in alkaline medium Part 1. Gold-zeolite-modified graphite electrode. Journal of Solid State Electrochemistry 12, 601-608. 

To improve the electrocatalytic activity of platinum and palladium, the ethanol oxidation on different metal adatom-modified, alloyed, and oxide-promoted Pt- and Pd-based electrocatalysts has been investigated in alkaline media. Firstly, El-Shafei et al. [76] studied the electrocatalytic effect of some metal adatoms (Pb, Tl, Cd) on ethanol oxidation at a Pt electrode in alkaline medium. All three metal adatoms, particularly Pb and Tl, improved the EOR activity of ft. More recently, Pt-Ni nanoparticles, deposited on carbon nanofiber (CNE) network by an electrochemical deposition method at various cycle numbers such as 40, 60, and 80, have been tested as catalysts for ethanol oxidadmi in alkaline medium [77]. The Pt-Ni alloying nature and Ni to ft atomic ratio increased with increasing of cycle number. The performance of PtNi80/CNF for the ethanol electrooxidation was better than that of the pure Pt40/CNF, PtNi40/CNF, and PtNi60/CNF. 

Elshafei AA,EhnaksoudSAA,Fouda AS (1995) Noble-metal-modified glassy-carbrai electrodes for ethylene-glycol oxidation in alkaline-medium. J Electroanal Chem 395(1-2) 181-187... 

Research into such catalysts started in the 1960s, when Jasinski (1964) discovered that cohalt phthalo-cyanine could catalyze the ORR in an alkaline medium. Fe and Co are the most commonly used metals for these catalysts. The origin of the electrocataly tic activity of N-containing non-Pt catalysts was generally recognized to he the N4-chelates (or Nj-chelates) of transition metals, due to the simultaneous presence of metal precursors, active carbon, and a nitrogen source under pyrolysis conditions. Beck (1977) proposed that the mechanism of the ORR catalyzed by such catalysts was mainly involved hy a modified... 

Chapter 1 discusses the current status of electrocatalysts development for methanol and ethanol oxidation. Chapter 2 presents a systematic study of electrocatalysis of methanol oxidation on pure and Pt or Pd overlayer-modified tungsten carbide, which has similar catalytic behavior to Pt. Chapters 3 and 4 outline the understanding of formic acid oxidation mechanisms on Pt and non-Pt catalysts and recent development of advanced electrocatalysts for this reaction. The faster kinetics of the alcohol oxidation reaction in alkaline compared to acidic medium opens up the possibility of using less expensive metal catalysts. Chapters 5 and 6 discuss the applications of Pt and non-Pt-based catalysts for direct alcohol alkaline fuel cells. 

Mixed oxides derived from thermal decomposition of LDHs have acid-base properties that influence the catalytic behavior of these materials and depend on the molar ratio Mii/m" ions, their diameters, charge, calcination temperature, and synthesis methods [50, 51]. The acid-base centers are highly active centers that participate in numerous reactions. These properties can be modified by the variation of the M /M molar ratio, by isomorph substitution of a part of M that are present in the structure with other divalent metal ions (such as NT, Be, Co, Zn +, Cu +, Mn +, Cr +, and Fe " ) and by isomorph substitution of a part of M" that are present in the structure with other trivalent metal ions (e.g. Ga T Fe T Co T NTT Mn T V T In T Rh T Ru ") [2]. With the increase of the M cation presence the amount of acid centers also increases in mixed oxides. Acidity depends on the nature of the M cations, for instance AP+ cations exhibit higher acidity than Fe +cations [1]. After thermal decomposition of LDHs, mixed oxides are formed that present solid bases. The alkalinity level depends on the synthesis method. Application of the coprecipitation and sol-gel methods leads to the formation of mixed oxides that have base centers of Lewis type with medium strength... 

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