Surface oxygen functional groups

At least one anodic or cathodic peak (wave) can be observed in the CV curves recorded in aqueous electrolyte solution. These peaks (waves) may be due to oxidation or reduction of surface oxygen functional groups similar to what was observed for various carbon electrodes [7,9,14,16,24,26,132]. On the basis of... 

The temperatures at which the oxygen surface functional groups decompose are also important. For platinum/C catalysts it was observed that if the metal reduction/heat treatment temperature exceeds the decomposition temperature of the majority of the surface oxygen functional groups the metal dispersion also increased [15,16]. 

If the oxidized carbon nanofibers are calcined at 573 K, the shoulder at 1740 cm and the band at 1720 cm becomes less pronounced (Fig. 4). The phenolic and asymmetric and S5nnmetric NO2 stretching vibration peaks have disappeared completely. Thus ketone, carboxylic, phenolic and nitro groups decompose if the carbon nanofibers are calcined at 573 K. The peak that remains at 1720 cm" is most likely due to lactones because these groups decompose between 600 and 950 K [31]. If the temperature is increased further to 873 K, the shoulder and peak at 1740 cm" and 1720 cm" have disappeared completely. It follows that the majority of the surface oxygen functional groups decompose at 573 K. 

In this respect, it is important to note that, depending on the pH, six soluble complexes, i.e., Co(H20)/ Co(H20)50H Co(H20) (OH)2, Co(H20)3(OH)3 , Co(H20)2(OH)4 and polynuclear C02OH, Co4(OH)4 could exist in aqueous solution [34], An electrostatic interaction between the negatively charged surface oxygen functional groups and these positively charged monomeric species cannot be ruled out. 

The metal dispersion does not change much as a function of heat treatment temperature. As was already shown by the FTIR results, heat treatment at 573 K results in the decomposition of the majority of the surface oxygen functional groups and after heat treatment at 873 K no surface oxygen functional groups could be detected. According to Rodriguez-Reinoso [5] the decomposition of... 

From the wide spectra, the total carbon, oxygen and cobalt content of the catalysts can be calculated (Table 5). Although the total metal content did not change significantly if the catalysts are calcined at 573 K and 873 K respectively the surface cobalt concentration decreased upon heat treatment at 873 K to such an extent that it was hardly possible to detect any cobalt species on the surface of the support from the XPS spectra. This indicates that the outer atomic layers changed upon heat treatment at 873 K. This could partly be due to the decomposition of the majority of the surface oxygen functional groups at this temperature but as already mentioned other effects should also be considered. ... 

Until now the influence of the surface oxygen functional groups on the metal dispersion have not been addressed. It is well-known that thermal desorption of... 

The factor that probably most complicates the study of structure-function relationships at carbon electrodes is the surface chemistry, specifically, the variety of surface oxygen functional groups that can exist, particularly on sp bonded materials... 

Mao Lei, Tong Shitang, Wang Ning. activated carbon used for analysis of surface oxygen functional groups Several discussions Boehm titration [J]. Carbon Technology, 2011,30(2) 17-19. 

Therefore, further acid treatment is necessary on both original activated carbons and these after high temperature graphitized and oxidation treatment can introduce the surface oxygenous functional groups. 24... 

The authors aim was to produce a text which critically reviews the available literature on solution adsorption phenomena and offers an interpretation of the surface-related interactions of activated carbons that is consistent for the adsorption of a wide variety of solutes ranging from strong electrolytes to organic non-electrolytes. The seven chapters cover the activation of carbon, surface oxygen functional groups and neutralization of base by acidic surface oxides, spectroscopic methods for molecular structure determinations on surfaces, nature of the electrical double layer, adsorption of electrolytes, and adsorption of weak and non-electrolytes from aqueous solution. 

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